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1.  Dimensions of Parental Alcohol Use/Problems and Offspring Temperament, Externalizing Behaviors and Alcohol Use/Problems 
Alcoholism, clinical and experimental research  2013;37(12):10.1111/acer.12196.
BACKGROUND
Alcohol consumption (AC) and alcohol-related problems (AP) are complex traits. How many factors reflecting parental AC and AP are present in the large prospectively followed Avon Longitudinal Study of Parents and Children cohort? Would these factors be uniquely associated with various temperamental and alcohol related outcomes in the children?
METHODS
We factor analyzed multiple items reflecting maternal and paternal AC and AP measured over a 12 year period from before the birth of the child (n=14,093 families). We examined, by linear regression controlling for socio-economic status SES, the relationship between scales derived from these factors and offspring early childhood temperament, externalizing traits and adolescent AC and AP (n’s ranging from 9,732 to 3,454).
RESULTS
We identified 5 coherent factors: typical maternal AC, maternal AC during pregnancy, maternal AP, paternal AC, and paternal AP. In univariate analyses, maternal and paternal AC and AP were modestly and significantly associated with low shyness, sociability, hyperactivity, and conduct problems in childhood and early adolescence; delinquent behavior at age 15; and AC and AP at ages 15 and 18. AC and AP at age 18 were more strongly predicted by parental factors than at age 15. Maternal AC during pregnancy uniquely predicted externalizing traits at ages 4, 13 and 15.
CONCLUSION
Parental AC and AP are complex multidimensional traits that differ in their association with a range of relevant measures in their children. Controlling for background AC and AP, self-reported levels of maternal AC during pregnancy uniquely predicted externalizing behaviors in childhood and adolescence.
doi:10.1111/acer.12196
PMCID: PMC3855174  PMID: 23895510
ALSPAC; alcohol consumption; parental alcohol use; temperament; externalizing problems; fetal alcohol exposure
2.  Differences in risk factors for self-harm with and without suicidal intent: Findings from the ALSPAC cohort 
Journal of Affective Disorders  2014;168(100):407-414.
Background
There is a lack of consensus about whether self-harm with suicidal intent differs in aetiology and prognosis from non-suicidal self-harm, and whether they should be considered as different diagnostic categories.
Method
Participants were 4799 members of the Avon Longitudinal Study of Parents and Children (ALSPAC), a UK population-based birth cohort who completed a postal questionnaire on self-harm with and without suicidal intent at age 16 years. Multinomial logistic regression analyses were used to examine differences in the risk factor profiles of individuals who self-harmed with and without suicidal intent.
Results
Many risk factors were common to both behaviours, but associations were generally stronger in relation to suicidal self-harm. This was particularly true for mental health problems; compared to those with non-suicidal self-harm, those who had harmed with suicidal intent had an increased risk of depression (OR 3.50[95% CI 1.64, 7.43]) and anxiety disorder (OR 3.50[95% CI 1.72, 7.13]). Higher IQ and maternal education were risk factors for non-suicidal self-harm but not suicidal self-harm. Risk factors that appeared specific to suicidal self-harm included lower IQ and socioeconomic position, physical cruelty to children in the household and parental self-harm.
Limitations
i) There was some loss to follow-up, ii) difficulty in measuring suicidal intent, iii) we cannot rule out the possibility of reverse causation for some exposure variables, iv) we were unable to identify the subgroup that had only ever harmed with suicidal intent.
Conclusion
Self-harm with and without suicidal intent are overlapping behaviours but with some distinct characteristics, indicating the importance of fully exploring vulnerability factors, motivations, and intentions in adolescents who self harm.
doi:10.1016/j.jad.2014.07.009
PMCID: PMC4160300  PMID: 25108277
ALSPAC; Adolescent; Self-harm; Suicide attempt; Longitudinal
3.  Prenatal exposure to binge pattern of alcohol consumption: mental health and learning outcomes at age 11 
The objective of the study is to investigate whether episodic binge pattern of alcohol consumption during pregnancy is independently associated with child mental health and academic outcomes. Using data from the prospective, population-based Avon Longitudinal Study of Parents and Children (ALSPAC), we investigated the associations between binge patterns of alcohol consumption during pregnancy (≥4 drinks per day) and child mental health [as rated by both parent (n = 4,610) and teacher (n = 4,274)] and academic outcomes [based on examination results (n = 6,939)] at age 11 years. After adjusting for prenatal and postnatal risk factors, binge pattern of alcohol consumption (≥4 drinks in a day on at least one occasion) during pregnancy was associated with higher levels of mental health problems (especially hyperactivity/inattention) in girls at age 11 years, according to parental report. After disentangling binge-pattern and daily drinking, binge-pattern drinking was independently associated with teacher-rated hyperactivity/inattention and lower academic scores in both genders. Episodic drinking involving ≥4 drinks per day during pregnancy may increase risk for child mental health problems and lower academic attainment even if daily average levels of alcohol consumption are low. Episodic binge pattern of drinking appears to be a risk factor for these outcomes, especially hyperactivity and inattention problems, in the absence of daily drinking.
Electronic supplementary material
The online version of this article (doi:10.1007/s00787-014-0599-7) contains supplementary material, which is available to authorized users.
doi:10.1007/s00787-014-0599-7
PMCID: PMC4186965  PMID: 25209690
Prenatal alcohol exposure; Fetal alcohol spectrum disorder; Academic achievement; Mental health problems; Hyperactivity
4.  Association between parent-infant interactions in infancy and disruptive behaviour disorders at age seven: a nested, case–control ALSPAC study 
BMC Pediatrics  2014;14(1):223.
Background
Effective early intervention to prevent oppositional/conduct disorders requires early identification of children at risk. Patterns of parent-child interaction may predict oppositional/conduct disorders but large community-based prospective studies are needed to evaluate this possibility.
Methods
We sought to examine whether the Mellow Parenting Observational System (MPOS) used to assess parent-infant interactions at one year was associated with psychopathology at age 7. The MPOS assesses positive and negative interactions between parent and child. It examines six dimensions: anticipation of child’s needs, responsiveness, autonomy, cooperation, containment of child distress, and control/conflict; these are summed to produce measures of total positive and negative interactions. We examined videos from the Avon Longitudinal Study of Parents and Children (ALSPAC) sub-cohort who attended the ‘Children in Focus’ clinic at one year of age. Our sample comprised 180 videos of parent-infant interaction: 60 from infants who received a psychiatric diagnostic categorisation at seven years and 120 randomly selected controls who were group-matched on sex.
Results
A negative association between positive interactions and oppositional/conduct disorders was found. With the exception of pervasive developmental disorders (autism), an increase of one positive interaction per minute predicted a 15% (95% CI: 4% to 26%) reduction in the odds of the infant being case diagnosed. There was no statistically significant relationship between negative parenting interactions and oppositional/conduct disorders, although negative interactions were rarely observed in this setting.
Conclusions
The Mellow Parenting Observation System, specifically low scores for positive parenting interactions (such as Responsiveness which encompasses parental warmth towards the infant), predicted later psychiatric diagnostic categorisation of oppositional/conduct disorders.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2431-14-223) contains supplementary material, which is available to authorized users.
doi:10.1186/1471-2431-14-223
PMCID: PMC4177234  PMID: 25193601
ALSPAC; Disruptive behaviour disorders; Parent-infant interactions; Mellow Parenting Observation System
5.  Childhood traumatic events and adolescent overgeneral autobiographical memory: Findings in a UK cohort 
Background
Overgeneral autobiographical memory has repeatedly been identified as a risk factor for adolescent and adult psychopathology but the factors that cause such over-generality remain unclear. This study examined the association between childhood exposure to traumatic events and early adolescent overgeneral autobiographical memory in a large population sample.
Methods
Thirteen-year-olds, n = 5,792, participating in an ongoing longitudinal cohort study (ALSPAC) completed a written version of the Autobiographical Memory Test. Performance on this task was examined in relation to experience of traumatic events, using data recorded by caregivers close to the time of exposure.
Results
Results indicated that experiencing a severe event in middle childhood increased the likelihood of an adolescent falling into the lowest quartile for autobiographical memory specificity (retrieving 0 or 1 specific memory) at age 13 by approximately 60%. The association persisted after controlling for a range of potential socio-demographic confounders.
Limitations
Data on the traumatic event exposures was limited by the relatively restricted range of traumas examined, and the lack of contextual details surrounding both the traumatic event exposures themselves and the severity of children's post-traumatic stress reactions.
Conclusions
This is the largest study to date of the association between childhood trauma exposure and overgeneral autobiographical memory in adolescence. Findings suggest a modest association between exposure to traumatic events and later overgeneral autobiographical memory, a psychological variable that has been linked to vulnerability to clinical depression.
Highlights
•Overgeneral autobiographical memory has been linked to trauma in childhood.•We examined associations between low AMT score and trauma exposure at age 13.•A severe middle childhood life event increased likelihood of low AMT by 60%.•This association was not appreciably attenuated after adjustment for confounders.
doi:10.1016/j.jbtep.2014.02.004
PMCID: PMC4053588  PMID: 24657714
Memory; Adolescence; Trauma; Depression; ALSPAC
6.  Adolescent Alcohol Use is Predicted by Childhood Temperament Factors Before Age 5, with Mediation Through Personality and Peers 
Alcoholism, clinical and experimental research  2013;37(12):10.1111/acer.12206.
Background:
Very few studies chart developmental pathways from early childhood to adolescent alcohol-related outcomes. We test whether measures of temperament collected from mothers at multiple assessments from 6 months through 5 years predict alcohol-related outcomes in mid-adolescence, the developmental pathways that mediate these effects, and whether there are gender differences in pathways of risk.
Methods:
Structural models were fit to longitudinal data from the Avon Longitudinal Study of Parents and Children, an epidemiological sample of pregnant women with delivery dates between April 1991 and December 1992, with children followed longitudinally. Temperamental characteristics were assessed at 6 time points from 6 to 69 months of age. Alcohol use and problems were assessed at age 15.5. Analyses here utilize data from 6,504 boys and 6,143 girls.
Results:
Childhood temperament prior to age 5 predicted adolescent alcohol use and problems at age 15.5 years, even after controlling for socio-demographic factors and parental alcohol problems. In both boys and girls, 2 largely uncorrelated and distinct temperament styles—children who were rated as having consistent emotional and conduct difficulties through age 5, and children who were rated as consistently sociable through age 5—both showed elevated rates of alcohol problems at age 15.5, but via different mediational pathways. In both genders, the association between emotional and conduct difficulties and alcohol problems was mediated through reduced conscientiousness and lower emotional stability. The association between sociability and alcohol problems was mediated through increased extraversion and sensation-seeking for both genders. Boys also showed mediation for sociability and alcohol outcomes through friendship characteristics, and girls through lower conscientiousness and reduced emotional stability.
Conclusions:
Our findings support multiple pathways to alcohol consumption and problems in adolescence. Some of these pathways are shared in boys and girls, while other risk factors are more salient in one gender or the other.
doi:10.1111/acer.12206
PMCID: PMC3823677  PMID: 23841856
ALSPAC; Temperament; Alcohol; Adolescence; Sex Differences
7.  Longitudinal Associations between Adolescent Psychotic Experiences and Depressive Symptoms 
PLoS ONE  2014;9(8):e105758.
Background
Psychotic experiences are prevalent in community samples and are highly correlated with depressive symptoms. This study aimed to investigate the longitudinal associations between psychotic experiences and depressive symptoms between adolescence and young adulthood.
Method
Prospective cohort study with a 6 year follow-up in a community sample of 7632 adolescents and young adults. Depressive symptoms were assessed with the Short Moods and Feelings Questionnaire and psychotic experiences with a semi-structured clinical interview at 12 and 18 years. Longitudinal and cross-sectional associations were investigated with regression and structural equation models.
Results
Depressive symptoms and psychotic experiences were associated at each time-point (12 years r = 0.486 [95% CI 0.457, 0.515]; 18 years r = 0.286 [95% CI 0.233, 0.339]) and there were longitudinal within-phenotype associations (depressive symptoms r = 0.252 [95% CI 0.205, 0.299]; psychotic experiences r = 0.662 [95% CI 0.595, 0.729]). There was an across-phenotype association between psychotic experiences at 12 and depressive symptoms at 18 r = 0.139 [95% CI 0.086, 0.192; p<0.001], but no association between depressive symptoms at 12 and psychotic experiences at 18 r = −0.022 [95% CI −0.032, 0.077; p = 0.891].
Conclusions
Longitudinal across-phenotype associations were substantially weaker than cross-sectional associations or within-phenotype longitudinal associations. Whilst psychotic experiences at 12 years were associated with a small increase in depression at 18 years, depression at 12 years was not associated with psychotic experiences at 18 years once across-phenotype cross-sectional and within-phenotype longitudinal associations were accounted for. This suggests that the biological mechanisms underlying depression at this age do not increase subsequent risk of psychotic experiences once they resolve.
doi:10.1371/journal.pone.0105758
PMCID: PMC4146535  PMID: 25162230
8.  Prevalence of Chlamydia in Young Adulthood and Association with Life Course Socioeconomic Position: Birth Cohort Study 
PLoS ONE  2014;9(8):e104943.
Background
Few estimates are available of chlamydia prevalence in the general population. Existing studies have limited scope to explore potential selection bias or associations with socioeconomic position.
Methods
We examined the prevalence of Chlamydia trachomatis infection and associations with life-course socioeconomic position in the Avon Longitudinal Study of Parents and Children in England. Chlamydia infection was measured through nucleic acid amplification test of urine specimens.
Results
4864 (51%) of those invited attended the clinic (mean age 17.8; SD 0.37 years). (60%) provided a urine specimen. Prevalence was 1.0% (95% CI 0.6 to 1.6) among participants reporting sexual activity. Risk of infection was strongly associated with life course social disadvantage and with recent sexual behaviour. After adjustment for other measures of disadvantage and for sexual behaviour the strongest risk factors for infection were lower maternal educational attainment (OR 9.1 (1.1, 76.7)) and lower participant educational attainment at age 11 (OR 5.0 (1.5, 16.5)). Both clinic attendance and agreement to test were lower amongst the disadvantaged. Adjustment for selective participation based on detailed information on non-participants approximately doubled prevalence estimates. Prevalence was higher in sexually active women (1.4% (0.7 to 2.4) than men (0.5% (0.1 to 1.3)).
Conclusions
Chlamydia prevalence in this general population sample was low even after adjustment for selective participation in testing. These estimates of prevalence and patterns of association with socioeconomic position may both reflect recent screening efforts. Prevalence was higher amongst the disadvantaged who were also less likely to engage in testing. Our results reveal the importance of monitoring and addressing inequalities in screening programme participation and outcomes.
doi:10.1371/journal.pone.0104943
PMCID: PMC4143219  PMID: 25153124
9.  The association between depressive symptoms from early to late adolescence and later use and harmful use of alcohol 
European Child & Adolescent Psychiatry  2014;23(12):1219-1230.
Depressive symptoms and alcohol misuse contribute substantially to the global health burden. These phenotypes often manifest, and frequently co-occur, during adolescence. However, few studies have examined whether both baseline levels of depressive symptoms and change in symptoms are associated with alcohol outcomes. In addition, inconsistent findings could be due to sex differences or the use of different alcohol outcomes. Using data from a prospective population-based cohort in the UK, we estimated trajectories of depressive symptoms from 12 years 10 months to 17 years 10 months, separately for male and female participants. We assessed whether baseline and change in depressive symptoms were associated with use and harmful use of alcohol at 18 years 8 months. Among females, increasing depressive symptoms were associated with increased alcohol use; whilst for males, there was little evidence of this. When examining harmful levels of alcohol use, baseline levels of depressive symptoms in males were weakly related to later harmful alcohol use but this association was attenuated substantially through adjustment for confounders. In contrast, both baseline symptoms and increase in symptoms were associated with later harmful alcohol use in females and these associations were not diminished by confounder adjustment. Elevated depressive symptoms during adolescence are positively associated with increases in both use and harmful use of alcohol at 18 years 8 months. These findings differ between the sexes. Further research is needed to examine the mechanisms underlying the link between depressive symptoms and harmful alcohol use to identify potentially modifiable factors for intervention.
Electronic supplementary material
The online version of this article (doi:10.1007/s00787-014-0600-5) contains supplementary material, which is available to authorized users.
doi:10.1007/s00787-014-0600-5
PMCID: PMC4246124  PMID: 25130265
ALSPAC; Adolescence; Depressive symptoms; Alcohol; Longitudinal
10.  Conduct problem trajectories and alcohol use and misuse in mid to late adolescence 
Drug and alcohol dependence  2013;133(1):100-107.
Background
We consider the strength of the relationship between types of conduct problems in early life and pattern of alcohol use during adolescence.
Methods
Children from the Avon Longitudinal Study of Parents and Children, a UK birth-cohort, had their level of conduct problems assessed repeatedly from 4 to 13 years using the maternal report Strengths and Difficulties Questionnaire. Developmental trajectories derived from these data were subsequently related to (i) patterns of alcohol use from 13 to 15 years, and (ii) hazardous alcohol used at age 16.
Results
Boys with ‘Adolescent Onset’ or ‘Early Onset Persistent’ conduct problems were much more likely to be high frequency drinkers between 13 and 15 years (OR 5.00 95% CI = [2.4, 10.6] and 3.9 95% CI = [2.1, 7.3] respectively) compared with those with Low or ‘Childhood Limited’ conduct. Adolescent Onset/Early Onset Persistent girls also had greater odds of this high-alcohol frequency drinking pattern (2.67 [1.4, 5.0] and 2.14 [1.2, 4.0] respectively). Associations were more moderate for risk of hazardous alcohol use at age 16. Compared to 32% among those with low conduct problems, over 40% of young people classified as showing Adolescent Onset/Early Onset Persistent conduct problems were drinking hazardously (OR 1.52 [1.09, 2.11] and 1.63 [1.22, 2.18] respectively).
Conclusions
Whilst persistent conduct problems greatly increase the risk of adolescent alcohol problems, the majority of adolescents reporting hazardous use at age 16 lack such a history. It is important, therefore, to undertake alcohol prevention among all young people as a priority, as well as target people with manifest conduct problems.
doi:10.1016/j.drugalcdep.2013.05.025
PMCID: PMC3786043  PMID: 23787037
ALSPAC; Conduct problems; Alcohol use; Adolescence; Trajectory
11.  Maternal smoking during pregnancy and offspring smoking initiation: assessing the role of intrauterine exposure 
Addiction (Abingdon, England)  2014;109(6):1013-1021.
Aims
To assess whether associations between maternal smoking during pregnancy and offspring smoking initiation are due to intrauterine mechanisms.
Design
Comparison of associations of maternal and partner smoking behaviour during pregnancy with offspring smoking initiation using partner smoking as a negative control (n = 6484) and a Mendelian randomization analysis (n = 1020), using a genetic variant in the mothers as a proxy for smoking cessation during pregnancy.
Setting
A longitudinal birth cohort in South West England.
Participants
Participants of the Avon Longitudinal Study of Parents and Children (ALSPAC).
Measurements
Smoking status during pregnancy was self-reported by mother and partner in questionnaires administered at pregnancy. Latent classes of offspring smoking initiation (non-smokers, experimenters, late-onset regular smokers and early-onset regular smokers) were previously developed from questionnaires administered at 14–16 years. A genetic variant, rs1051730, was genotyped in the mothers.
Findings
Both mother and partner smoking were similarly positively associated with offspring smoking initiation classes, even after adjustment for confounders. Odds ratios (OR) [95% confidence interval (CI)] for class membership compared with non-smokers were: experimenters: mother OR = 1.33 (95% CI = 1.06, 1.67), partner OR = 1.28 (95% CI = 1.06, 1.55), late-onset regular smokers: mother OR = 1.80 (95% CI = 1.43, 2.26), partner OR = 1.86 (95% CI = 1.52, 2.28) and early-onset regular smokers: mother OR = 2.89 (95% CI = 2.12, 3.94), partner OR = 2.50 (95% CI = 1.85, 3.37). There was no clear evidence for a dose–response effect of either mother or partner smoking heaviness on class membership. Maternal rs1051730 genotype was not clearly associated with offspring smoking initiation class in pre-pregnancy smokers (P = 0.35).
Conclusion
The association between smoking during pregnancy and offspring smoking initiation does not appear to operate through intrauterine mechanisms.
doi:10.1111/add.12514
PMCID: PMC4114534  PMID: 24521169
ALSPAC; intrauterine; maternal smoking; Mendelian randomization; negative control; offspring smoking; pregnancy; tobacco
12.  Outcomes of childhood conduct problem trajectories in early adulthood: findings from the ALSPAC study 
Although conduct problems in childhood are stably associated with problem outcomes, not every child who presents with conduct problems is at risk. This study extends previous studies by testing whether childhood conduct problem trajectories are predictive of a wide range of other health and behavior problems in early adulthood using a general population sample. Based on 7,218 individuals from the Avon longitudinal study of parents and children, a three-step approach was used to model childhood conduct problem development and identify differences in early adult health and behavior problems. Childhood conduct problems were assessed on six occasions between age 4 and 13 and health and behavior outcomes were measured at age 18. Individuals who displayed early-onset persistent conduct problems throughout childhood were at greater risk for almost all forms of later problems. Individuals on the adolescent-onset conduct problem path consumed more tobacco and illegal drugs and engaged more often in risky sexual behavior than individuals without childhood conduct problems. Levels of health and behavior problems for individuals on the childhood-limited path were in between those for stable low and stable high trajectories. Childhood conduct problems are pervasive and substantially affect adjustment in early adulthood both in at-risk samples as shown in previous studies, but also in a general population sample. Knowing a child’s developmental course can help to evaluate the risk for later maladjustment and be indicative of the need for early intervention.
Electronic supplementary material
The online version of this article (doi:10.1007/s00787-013-0488-5) contains supplementary material, which is available to authorized users.
doi:10.1007/s00787-013-0488-5
PMCID: PMC4172989  PMID: 24197169
Conduct problems; ALSPAC; Trajectory outcomes
13.  Depression Symptom Trajectories and Associated Risk Factors among Adolescents in Chile  
PLoS ONE  2013;8(10):e78323.
Adolescence is a key period for studying the development of depression, with studies in Europe and North America showing a pattern of elevated risk that begins in early adolescence and continues to increase as adolescents age. Few studies have examined the course of adolescent depression and associated risk factors in low and middle-income countries. This longitudinal cohort study examined depression symptom trajectories and risk factors in a sample of socio-economically disadvantaged adolescents in Chile (n = 2,508). Data were collected over an 18-month period as part of a clinical trial for secondary students aged 12 to 18 (median age 14). Clinical levels of depression were prevalent in this sample at baseline (35% for girls and 28% for boys); yet latent growth models of symptom trajectories revealed a pattern of decreasing symptoms over time. There was evidence of an anxiety-depression developmental pathway for girls, with elevated anxiety levels initially predicting poorer depression outcomes later on. Poor problem-solving skills were associated with initial depression levels but did not predict the course of depressive symptoms. Critically, the declining symptom trajectories raise important methodological issues regarding the effects of repeated assessment in longitudinal studies.
doi:10.1371/journal.pone.0078323
PMCID: PMC3795668  PMID: 24147131
14.  Prenatal alcohol exposure and offspring cognition and school performance. A ‘Mendelian randomization’ natural experiment 
Background There is substantial debate as to whether moderate alcohol use during pregnancy could have subtle but important effects on offspring, by impairing later cognitive function and thus school performance. The authors aimed to investigate the unconfounded effect of moderately increased prenatal alcohol exposure on cognitive/educational performance.
Methods We used mother-offspring pairs participating in the Avon Longitudinal Study of Parents and Children (ALSPAC) and performed both conventional observational analyses and Mendelian randomization using an ADH1B variant (rs1229984) associated with reduced alcohol consumption. Women of White European origin with genotype and self-reported prenatal alcohol consumption, whose offspring’s IQ score had been assessed in clinic (N = 4061 pairs) or Key Stage 2 (KS2) academic achievement score was available through linkage to the National Pupil Database (N = 6268), contributed to the analyses.
Results Women reporting moderate drinking before and during early pregnancy were relatively affluent compared with women reporting lighter drinking, and their children had higher KS2 and IQ scores. In contrast, children whose mothers’ genotype predisposes to lower consumption or abstinence during early pregnancy had higher KS2 scores (mean difference +1.7, 95% confidence interval +0.4, +3.0) than children of mothers whose genotype predisposed to heavier drinking, after adjustment for population stratification.
Conclusions Better offspring cognitive/educational outcomes observed in association with prenatal alcohol exposure presumably reflected residual confounding by factors associated with social position and maternal education. The unconfounded Mendelian randomization estimates suggest a small but potentially important detrimental effect of small increases in prenatal alcohol exposure, at least on educational outcomes.
doi:10.1093/ije/dyt172
PMCID: PMC3807618  PMID: 24065783
Alcohol dehydrogenase; causality; cognition; confounding factors; educational measurement; ethanol; Mendelian randomization analysis; pregnancy
15.  Which Behavioral, Emotional and School Problems in Middle-Childhood Predict Early Sexual Behavior? 
Journal of Youth and Adolescence  2013;43(4):507-527.
Mental health and school adjustment problems are thought to distinguish early sexual behavior from normative timing (16–18 years), but little is known about how early sexual behavior originates from these problems in middle-childhood. Existing studies do not allow for co-occurring problems, differences in onset and persistence, and there is no information on middle-childhood school adjustment in relationship to early sexual activity. This study examined associations between several middle-childhood problems and early sexual behavior, using a subsample (N = 4,739, 53 % female, 98 % white, mean age 15 years 6 months) from a birth cohort study, the Avon Longitudinal Study of Parents and Children. Adolescents provided information at age 15 on early sexual behavior (oral sex and/or intercourse) and sexual risk-taking, and at age 13 on prior risk involvement (sexual behavior, antisocial behavior and substance use). Information on hyperactivity/inattention, conduct problems, depressive symptoms, peer relationship problems, school dislike and school performance was collected in middle-childhood at Time 1 (6–8 years) and Time 2 (10–11 years). In agreement with previous research, conduct problems predicted early sexual behavior, although this was found only for persistent early problems. In addition, Time 2 school dislike predicted early sexual behavior, while peer relationship problems were protective. Persistent early school dislike further characterized higher-risk groups (early sexual behavior preceded by age 13 risk, or accompanied by higher sexual risk-taking). The study establishes middle-childhood school dislike as a novel risk factor for early sexual behavior and higher-risk groups, and the importance of persistent conduct problems. Implications for the identification of children at risk and targeted intervention are discussed, as well as suggestions for further research.
Electronic supplementary material
The online version of this article (doi:10.1007/s10964-013-9973-x) contains supplementary material, which is available to authorized users.
doi:10.1007/s10964-013-9973-x
PMCID: PMC3949009  PMID: 23824981
Sexual behavior; Adolescent; Conduct problems; School engagement; ALSPAC
16.  Characterizing Patterns of Smoking Initiation in Adolescence: Comparison of Methods for Dealing With Missing Data 
Nicotine & Tobacco Research  2011;13(12):1266-1275.
Introduction:
Tobacco use is common and remains one of the leading causes of preventable death in developed countries. Smoking commonly begins in adolescence, and hence, it is important to understand how smoking behavior develops during this period.
Methods:
In a U.K.-based birth cohort, we analyzed repeated measures of smoking frequency in a sample of 7,322 young adolescents. Latent class analysis was used to summarize the data, and the resulting classes of behavior were related to a range of smoking risk factors. Results from a complete case analysis were compared with estimation using full-information maximum likelihood (FIML) and estimation using multiple imputation (MI).
Results:
Fifty-three percent of the sample reported having smoked a whole cigarette by age 16 years. The longitudinal data were summarized by 4 distinct patterns of smoking initiation: nonsmokers (79.7%), experimenters (10.3%), late-onset regular smokers (5.5%), and early-onset regular smokers (4.5%). Social disadvantage, other substance use, conduct problems, and female sex were strongly related to being a regular smoker; however, no risk factors studied showed any strong or consistent association with experimentation. In the complete case sample, smoking prevalence was lower, and in addition, the association between different smoking patterns and covariates was often inconsistent with those obtained through FIML/MI.
Conclusions:
Most young people have experimented with tobacco smoking by age 16 years, and regular smoking is established in a substantial minority characterized by social disadvantage, other substance, use and conduct disorder. Prevention strategies should focus on this subgroup as most children who experiment with tobacco do not progress to regular smoking.
doi:10.1093/ntr/ntr161
PMCID: PMC3223580  PMID: 21994336
17.  TESTING A LEVEL OF RESPONSE TO ALCOHOL-BASED MODEL OF HEAVY DRINKING AND ALCOHOL PROBLEMS IN 1,905 17-YEAR-OLDS 
Background
The low level of response (LR) to alcohol is one of several genetically-influenced characteristics that increase the risk for heavy drinking and alcohol problems. Efforts to understand how LR operates through additional life influences have been carried out primarily in modest sized U.S.-based samples with limited statistical power, raising questions about generalizability and about the importance of components with smaller effects. This study evaluates a full LR-based model of risk in a large sample of adolescents from the U.K.
Methods
Cross-sectional structural equation models (SEM) were used for the approximate first half of the age 17 subjects assessed by the Avon Longitudinal Study of Parents and Children (ALSPAC), generating data on 1,905 adolescents (0 age 17.8 years, 44.2% males). LR was measured with the Self-Rating of the Effects of Alcohol (SRE) Questionnaire, outcomes were based on drinking quantities and problems, and standardized questionnaires were used to evaluate peer substance use, alcohol expectancies, and using alcohol to cope with stress.
Results
In this young and large U.K. sample, a low LR related to more adverse alcohol outcomes both directly and through partial mediation by all three additional key variables (peer substance use, expectancies, and coping). The models were similar in males and females.
Conclusions
These results confirm key elements of the hypothesized LR-based model in a large U.K. sample, supporting some generalizability beyond U.S. groups. They also indicate that with enough statistical power multiple elements contribute to how LR relates to alcohol outcomes, and reinforce the applicability of the model to both genders.
doi:10.1111/j.1530-0277.2011.01536.x
PMCID: PMC3183150  PMID: 21762180
ALSPAC; alcohol; level of response; structural equation models; adolescents
18.  Maternal and Paternal Smoking During Pregnancy and Risk of ADHD Symptoms in Offspring: Testing for Intrauterine Effects 
American Journal of Epidemiology  2012;176(3):261-268.
Maternal smoking during pregnancy is associated with attention deficit hyperactivity disorder (ADHD) in offspring. It is assumed by many that this association is causal. Others suggest that observed associations are due to unmeasured genetic factors or other confounding factors. The authors compared risks of maternal smoking during pregnancy with those of paternal smoking during pregnancy. With a causal intrauterine effect, no independent association should be observed between paternal smoking and offspring ADHD. If the association is due to confounding factors, risks of offspring ADHD should be of similar magnitudes regardless of which parent smokes. This hypothesis was tested in 8,324 children from a well-characterized United Kingdom prospective cohort study, the Avon Longitudinal Study of Parents and Children (data from 1991–2000). Associations between offspring ADHD and maternal and paternal smoking during pregnancy were compared using regression analyses. Offspring ADHD symptoms were associated with exposure to both maternal and paternal smoking during pregnancy (mothers: β = 0.25, 95% confidence interval: 0.18, 0.32; fathers: β = 0.21, 95% confidence interval: 0.15, 0.27). When paternal smoking was examined in the absence of maternal smoking, associations remained and did not appear to be due to passive smoking exposure in utero. These findings suggest that associations between maternal smoking during pregnancy and child ADHD may be due to genetic or household-level confounding rather than to causal intrauterine effects.
doi:10.1093/aje/kwr510
PMCID: PMC3406617  PMID: 22791738
attention deficit disorder with hyperactivity; causality; confounding factors (epidemiology); maternal exposure; paternal exposure; pregnancy; prenatal exposure delayed effects; smoking
19.  Adolescent self-harm and suicidal thoughts in the ALSPAC cohort: a self-report survey in England 
BMC Psychiatry  2012;12:69.
Background
Substantial numbers of adolescents self-harm, but the majority of cases do not reach the attention of medical services, making community studies essential. The prevalence of suicidal thoughts and plans at this age, and the inter-relationships between suicidal thoughts, plans and self-harm remain largely unexplored.
Method
Cross-sectional analysis of self-reported questionnaire data collected from members of the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort, England. Respondents (n = 4810) were aged 16–17 years old and have been followed up since birth.
Results
Altogether 905 (18.8%) respondents had ever self-harmed. The prevalence of lifetime self-harm was higher in females (25.6%) than males (9.1%). The most commonly used method was self-cutting: this was used alone or in combination in 73.5% of episodes, compared to 10.0% who took overdoses alone or in combination with other methods. Of those who reported self-harm, 25.3% wanted to die during the most recent episode. Concurrent depression was associated with a greatly increased risk of self-harm (OR 5.43). Only 12.4% of participants sought medical help following their most recent episode of self-harm, although this figure was higher (30.1%) where self-harm was carried out with desire to die. Of the whole sample, 15.8% had ever thought of killing themselves, and 4.3% had ever made plans to kill themselves. Compared to those who had never self-harmed, those who had self-harmed but not wanted to die during the most recent episode were at increased risk of ever having had suicidal thoughts (37.6% compared to 7.8% χ2 =102.3, p < 0.001) and ever making suicidal plans (8.7% compared to 0.7%, χ2 =166.9, p < 0.001). As the frequency of self-harm increased, so did the risk of suicidal thoughts and plans.
Conclusions
Self-harm and suicidal thoughts are common among 16/17 year olds. Although the majority of self-harm behaviour is not accompanied by a desire to die, all self-harm regardless of motivation is associated with increased risk of suicidal thoughts and plans, particularly when it is carried out repeatedly.
doi:10.1186/1471-244X-12-69
PMCID: PMC3439325  PMID: 22737989
Self-harm; Suicidal thoughts; Suicidal plans; Adolescence
20.  40,000 memories in young teenagers: Psychometric properties of the Autobiographical Memory Test in a UK cohort study 
Memory (Hove, England)  2012;20(3):300-320.
Although the Autobiographical Memory Test (AMT) is widely used its psychometric properties have rarely been investigated. This paper utilises data gathered from a 10-item written version of the AMT, completed by 5792 adolescents participating in the Avon Longitudinal Study of Parents and Children, to examine the psychometric properties of the measure. The results show that the scale derived from responses to the AMT operates well over a wide range of scores, consistent with the aim of deriving a continuous measure of over-general memory. There was strong evidence of group differences in terms of gender, low negative mood, and IQ, and these were in agreement when comparing an item response theory (IRT) approach with that based on a sum score. One advantage of the IRT model is the ability to assess and consequently allow for differential item functioning. This additional analysis showed evidence of response bias for both gender and mood, resulting in attenuation in the mean differences in AMT across these groups. Implications of the findings for the use of the AMT measure in different samples are discussed.
doi:10.1080/09658211.2012.656846
PMCID: PMC3379787  PMID: 22348421
Avon Longitudinal Study of Parents and Children; ALSPAC; Autobiographical Memory Test; AMT; Graded response model; Differential item functioning; Mood congruence
21.  Dog Ownership during Pregnancy, Maternal Activity, and Obesity: A Cross-Sectional Study 
PLoS ONE  2012;7(2):e31315.
The Avon Longitudinal Study of Parents and Children (ALSPAC) is an observational study of 14273 UK pregnant singleton mothers in 1990/1991. We examined outcomes of self report of strenuous activity (hours per week) at 18 and 32 weeks of gestation, hours spent in leisure-time physical activities and types, and pre-pregnancy body mass index (BMI); overweight status was defined as pre-pregnancy BMI≥25 and obesity BMI≥30. Pet ownership and activity data were reported for 11,466 mothers. Twenty-five percent of mothers owned at least one dog. There was a positive relationship between participation in activity at least once a week and dog ownership (at 18 weeks, Odds ratio 1.27, 95% confidence interval 1.11–1.44, P<0.001). Dog owners were 50% more likely to achieve the recommended 3 hours activity per week, equivalent to 30 minutes per day, most days of the week (1.53, 1.35–1.72, P<0.001). Dog owners were also more likely to participate in brisk walking activity than those who did not have a dog (compared to no brisk walking 2–6 hrs per week 1.43, 1.23 to 1.67, P<0.001; 7+ hrs per week 1.80, 1.43 to 2.27, P<0.001). However, no association was found with any other types of activities and there was no association between dog ownership and weight status. During the time period studied, pregnant women who had dogs were more active, through walking, than those who did not own dogs. As walking is a low-risk exercise, participation of pregnant women in dog walking activities may be a useful context to investigate as part of a broader strategy to improve activity levels in pregnant women.
doi:10.1371/journal.pone.0031315
PMCID: PMC3280272  PMID: 22355356
22.  Patterns of Alcohol Use in Early Adolescence Predict Problem Use at Age 16 
Aims: Teenagers in the UK report some of the highest rates of alcohol use in Europe. We identify patterns of alcohol use in early adolescence and relate these to hazardous and harmful alcohol use at age 16. Methods: In a UK birth cohort, we analysed repeated measures of alcohol use from age 13 to 15 in a sample of 7100 adolescents. Data on drinking frequency and typical consumption when drinking were modelled separately using a pair of latent class models. Classes of alcohol-use behaviour were contrasted across a range of risk factors and then to hazardous and harmful alcohol use as assessed using the Alcohol Use Disorders Identification Test scale at age 16. Results: Heterogeneity in drinking frequency and consumption could each be captured with three classes corresponding to low, medium and high levels. In total, 14.2% were classified as high-frequency and 8.9% as high consumption alcohol users. Socio-demographic factors, maternal substance use and the young persons' use of tobacco and cannabis were associated with class membership. At age 16, 29% were drinking hazardously and a further 5.6% were assessed as harmful drinkers. Young people in the high drinking frequency or consumption class had a 9-fold increased risk of reporting harmful drinking at age 16. Conclusions: By the age of 16, a substantial proportion of teenagers in this sample were drinking at levels that could be considered hazardous or harmful for an adult. Patterns of alcohol exposure in early adolescence were strongly associated with later alcohol use. Altering drinking patterns in middle adolescence has the potential to reduce harmful use in later adolescence.
doi:10.1093/alcalc/agr156
PMCID: PMC3284685  PMID: 22215001
23.  Links Between Co-occurring Social-Communication and Hyperactive-Inattentive Trait Trajectories 
Objective
There is overlap between an autistic and hyperactive-inattentive symptomatology when studied cross-sectionally. This study is the first to examine the longitudinal pattern of association between social-communication deficits and hyperactive-inattentive symptoms in the general population, from childhood through adolescence. We explored the interrelationship between trajectories of co-occurring symptoms, and sought evidence for shared prenatal/perinatal risk factors.
Method
Study participants were 5,383 singletons of white ethnicity from the Avon Longitudinal Study of Parents and Children (ALSPAC). Multiple measurements of hyperactive-inattentive traits (Strengths and Difficulties Questionnaire) and autistic social-communication impairment (Social Communication Disorder Checklist) were obtained between 4 and 17 years. Both traits and their trajectories were modeled in parallel using latent class growth analysis (LCGA). Trajectory membership was subsequently investigated with respect to prenatal/perinatal risk factors.
Results
LCGA analysis revealed two distinct social-communication trajectories (persistently impaired versus low-risk) and four hyperactive-inattentive trait trajectories (persistently impaired, intermediate, childhood-limited and low-risk). Autistic symptoms were more stable than those of attention-deficit/hyperactivity disorder (ADHD) behaviors, which showed greater variability. Trajectories for both traits were strongly but not reciprocally interlinked, such that the majority of children with a persistent hyperactive-inattentive symptomatology also showed persistent social-communication deficits but not vice versa. Shared predictors, especially for trajectories of persistent impairment, were maternal smoking during the first trimester, which included familial effects, and a teenage pregnancy.
Conclusions
Our longitudinal study reveals that a complex relationship exists between social-communication and hyperactive-inattentive traits. Patterns of association change over time, with corresponding implications for removing exclusivity criteria for ASD and ADHD, as proposed for DSM-5.
doi:10.1016/j.jaac.2011.05.015
PMCID: PMC3163265  PMID: 21871371
social-communication trait; hyperactive-inattentive trait; maternal smoking; teenage pregnancy; ALSPAC
24.  Relationships of Risk Factors for Pre-Eclampsia with Patterns of Occurrence of Isolated Gestational Proteinuria during Normal Term Pregnancy 
PLoS ONE  2011;6(7):e22115.
Background
Isolated gestational proteinuria may be part of the pre-eclampsia disease spectrum. Confirmation of its association with established pre-eclampsia risk factors and higher blood pressure in uncomplicated pregnancies would support this concept.
Methods
Data from 11,651 women from the Avon Longitudinal Study of Parents and Children who had a term live birth but did not have pre-existing hypertension or diabetes or develop gestational diabetes or preeclampsia were used. Proteinuria was assessed repeatedly (median 12 measurements per woman) by dipstick and latent class analysis was used to identify subgroups of the population with different patterns of proteinuria in pregnancy.
Results
Higher maternal pre-pregnancy body mass index (BMI), younger age, nulliparity and twin pregnancy were independently associated with increased odds of any proteinuria in pregnancy. Women who experienced proteinuria showed five patterns: proteinuria in early pregnancy only (≤20 weeks gestation), and onset at 21–28 weeks, 29–32 weeks, 33–36 weeks and ≥37 weeks gestation. There were higher odds of proteinuria onset after 33 weeks in obese women and after 37 weeks in nulliparous women compared with normal weight and multiparous women respectively. Smoking in pregnancy was weakly negatively associated with odds of proteinuria onset after 37 weeks. Twin pregnancies had higher odds of proteinuria onset from 29 weeks. In women with proteinuria onset after 33 weeks blood pressure was higher in early pregnancy and at the end of pregnancy.
Conclusions
Established pre-eclampsia risk factors were related to proteinuria occurrence in late gestation in healthy term pregnancies, supporting the hypothesis that isolated gestational proteinuria may represent an early manifestation of pre-eclampsia.
doi:10.1371/journal.pone.0022115
PMCID: PMC3138774  PMID: 21789220
25.  Family Pet Ownership during Childhood: Findings from a UK Birth Cohort and Implications for Public Health Research 
In developed nations, approximately half of household environments contain pets. Studies of Human-Animal Interaction (HAI) have proposed that there are health benefits and risks associated with pet ownership. However, accurately demonstrating and understanding these relationships first requires a better knowledge of factors associated with ownership of different pet types. A UK birth cohort, the Avon Longitudinal Study of Parents and Children (ALSPAC), were used to collect pet ownership data from the mothers, from gestation to child age 10 years old. 14,663 children were included in the study, of which mothers of 13,557 reported pet information at gestation, and 7,800 by age 10. Pet types recorded include cat, dog, rabbit, rodent, bird, fish and tortoise/turtle. The dataset also contains a number of demographic, socioeconomic and behavioural variables relevant to human health behaviour. Logistic regression was used to build multivariable models for ownership of each pet type at age 7 years. Family pet ownership increased during childhood, in particular rabbits, rodents and fish. A number of socioeconomic and demographic factors were associated with ownership of different pet types and the effects differed depending on the pet type studied. Variables which require consideration by researchers include gender, presence of older siblings, ethnicity, maternal and paternal education, maternal and paternal social class, maternal age, number of people in the household, house type, and concurrent ownership of other pets. Whether the mother had pets during her childhood was a strong predictor of pet ownership in all models. In HAI studies, care should be taken to control for confounding factors, and to treat each pet type individually. ALSPAC and other similar birth cohorts can be considered a potential resource for research into the effects of pet ownership during childhood.
doi:10.3390/ijerph7103704
PMCID: PMC2996187  PMID: 21139856
ALSPAC; pet; dog; cat; child

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