Background

Most information about the lifetime prevalence of mental disorders comes from retrospective surveys, but how much these surveys have undercounted due to recall failure is unknown. We compared results from a prospective study with those from retrospective studies.

Method

The representative 1972–1973 Dunedin New Zealand birth cohort (n=1037) was followed to age 32 years with 96% retention, and compared to the national New Zealand Mental Health Survey (NZMHS) and two US National Comorbidity Surveys (NCS and NCS-R). Measures were research diagnoses of anxiety, depression, alcohol dependence and cannabis dependence from ages 18 to 32 years.

Results

The prevalence of lifetime disorder to age 32 was approximately doubled in prospective as compared to retrospective data for all four disorder types. Moreover, across disorders, prospective measurement yielded a mean past-year-to-lifetime ratio of 38% whereas retrospective measurement yielded higher mean past-year-to-lifetime ratios of 57% (NZMHS, NCS-R) and 65% (NCS).

Conclusions

Prospective longitudinal studies complement retrospective surveys by providing unique information about lifetime prevalence. The experience of at least one episode of DSM-defined disorder during a lifetime may be far more common in the population than previously thought. Research should ask what this means for etiological theory, construct validity of the DSM approach, public perception of stigma, estimates of the burden of disease and public health policy.

The long-term effects of poor maternal oral health are unknown. We determined whether maternal oral health when children were young was a risk indicator for caries experience in adulthood, using oral examination and interview data from age-5 and age-32 assessments in the Dunedin Study, and maternal self-rated oral health data from the age-5 assessment. The main outcome measure was probands’ caries status at age 32. Analyses involved 835 individuals (82.3% of the surviving cohort) dentally examined at both ages, whose mothers were interviewed at the age-5 assessment. There was a consistent gradient in age-32 caries experience across the categories of maternal self-rated oral health status (from the age-5 assessment): it was greatest among the probands whose mothers rated their oral health as “poor” or who were edentulous, and lowest among those whose mothers rated their oral health as “excellent”. Unfavorable maternal self-rated oral health when children are young should be regarded as a risk indicator for poor oral health among offspring as they reach adulthood.

To date, the evidence supporting the benefits of dental visiting comes from cross-sectional studies. We investigated whether long-term routine dental visiting was associated with lower experience of dental caries and missing teeth, and better self-rated oral health, by age 32. A prospective cohort study in New Zealand examined 932 participants’ use of dentistry at ages 15, 18, 26, and 32. At each age, routine attenders (RAs) were identified as those who (a) usually visited for a check-up, and (b) had made a dental visit during the previous 12 months. Routine attending prevalence fell from 82% at age 15 to 28% by 32. At any given age, routine attenders had better-than-average oral health, fewer had teeth missing due to caries, and they had lower mean DS and DMFS scores. By age 32, routine attenders had better self-reported oral health and less tooth loss and caries. The longer routine attendance was maintained, the stronger the effect. Routine dental attendance is associated with better oral health.

To date, the evidence supporting the benefits of dental visiting comes from cross-sectional studies. We investigated whether long-term routine dental visiting was associated with lower experience of dental caries and missing teeth, and better self-rated oral health, by age 32. A prospective cohort study in New Zealand examined 932 participants’ use of dentistry at ages 15, 18, 26, and 32. At each age, routine attenders (RAs) were identified as those who (a) usually visited for a check-up, and (b) had made a dental visit during the previous 12 months. Routine attending prevalence fell from 82% at age 15 to 28% by 32. At any given age, routine attenders had better-than-average oral health, fewer had teeth missing due to caries, and they had lower mean DS and DMFS scores. By age 32, routine attenders had better self-reported oral health and less tooth loss and caries. The longer routine attendance was maintained, the stronger the effect. Routine dental attendance is associated with better oral health.

Objective

To examine predictors of dental anxiety trajectories in a longitudinal study of New Zealanders.

Methods

Prospective study of a complete birth cohort born in 1972/73 in Dunedin, New Zealand, with dental anxiety scale (DAS) scores and dental utilization determined at ages 15, 18, 26 and 32 years. Personality traits were assessed at a superfactor and (more fine-grained) subscale level via the Multidimensional Personality Questionnaire at age 18 years. Group-based trajectory analysis was used to identify dental anxiety trajectories.

Results

DAS scores from at least three assessments were available for 828 participants. Six dental anxiety trajectories were observed: stable nonanxious low (39.6%); stable nonanxious medium (37.9%); recovery (1.6%); adult-onset anxious (7.7%); stable anxious (7.2%) and adolescent-onset anxious (5.9%). Multivariate analysis showed that males and those with higher DMFS at age 15 years were more likely to be in the stable nonanxious low trajectory group. Membership of the stable nonanxious medium group was predicted by the dental caries experience at age 15 years. Participants who had lost one or more teeth between ages 26 and 32 years had almost twice the relative risk for membership of the adult-onset anxious group. Personality traits predicted group membership. Specifically, high scorers (via median split) on the ‘stress reaction’ subscale had over twice the risk of being in the stable anxious group; low scorers on the traditionalism subscale were more likely to be members of the recovery trajectory group; and high scorers on the ‘social closeness’ subscale had half the risk of being in the stable anxious group. Dental caries experience at age 5 years was also a predictor for the stable anxious group. Membership of the late-adolescent-onset anxious group was predicted by higher dental caries experience by age 15 years, but none of the other predictors was significant.

Conclusion

Six discrete trajectories of dental anxiety have been observed. Some trajectories (totalling more than 90% of the cohort) had clear associations with external influences, but others were more strongly associated with characteristics such as personality traits. A mix of both influences was observed with only the stable anxious dental anxiety trajectory.

Objective

To assess the influence of infant breast feeding on C reactive protein (CRP), a marker of low grade inflammation associated with cardiovascular mortality independent of serum cholesterol concentrations.

Design

Serum CRP, total cholesterol, anthropometric, and blood pressure measurements were performed along with assessment of infant breast feeding duration, birth weight, smoking status, adult socioeconomic status, number of health problems, and hormonal contraceptive use.

Setting

A New Zealand predominantly European descent community birth cohort.

Participants

822 men and women aged 26 years.

Main results

There was a significant linear relation (p<0.001) between duration of breast feeding and adult CRP level in women. The geometric means (IQR) for CRP were 2.22 (1, 4) mg/l for women breast fed for six months or more and 3.95 (2, 8) mg/l for women not breast fed (ratio, 95% confidence interval (CI): 0.69 (0.55 to 0.87). The linear association between cholesterol and breast feeding was also significant (p = 0.01), the geometric mean (IQR) total cholesterol levels being 4.62 (4.10, 5.10) for those breast fed for six months or more and 5.04 (4.5, 5.80) for those not breast fed (ratio, 95% CI: 0.92 (0.87, 0.98). There was no relation between CRP or total cholesterol and duration of breast feeding in men.

Conclusions

The findings of lower CRP with an increased duration of breast feeding in women suggest early postnatal nutrition may influence long term cardiovascular risk.

According to theory, health beliefs are related to health behaviors. We investigated whether individuals who hold favorable oral-health-related beliefs over time have better adult oral health than those who do not. Beliefs about the efficacy of water fluoridation, keeping the mouth clean, avoiding sweet foods, visiting the dentist, using dental floss, and using fluoridated toothpaste were assessed in a birth cohort at ages 15, 18, and 26 years. At each age, the majority of participants endorsed the importance of each practice. However, there was also evidence of instability across time. Individuals who held stable favorable dental beliefs from adolescence through adulthood had fewer teeth missing due to caries, less periodontal disease, better oral hygiene, better self-rated oral health, and more restorations. Dental beliefs can change between adolescence and young adulthood, and these changes are related to oral health. In particular, unfavorable dental health beliefs are related to poorer oral health.

Dental caries is a chronic, cumulative disease, but no studies have investigated longitudinal patterns of caries experience. The objective of this study was to identify and describe developmental trajectories of caries experience in the permanent dentition to age 32. Longitudinal caries data for 955 participants in a longstanding birth cohort study were analyzed by trajectory analysis. Three caries experience trajectories were identified by the SAS macro PROC TRAJ; these were categorized as “high” (~ 15%), “medium” (~ 43%), and “low” (~ 42%) DMFS (Decayed, Missing, and Filled Surfaces). All were relatively linear, although the higher trajectories were more “S-shaped”. This effect disappeared following adjustment for the number of unaffected surfaces remaining at each age, suggesting that, among individuals following a similar caries trajectory, caries rate is relatively constant across time.

The majority of what is known of the experience of dental caries among adults is from cross-sectional studies, and there are surprisingly few population-level longitudinal studies of dental caries among adults. Dental examinations were conducted at age 26 and again at age 32 among participants in a longstanding prospective study of a birth cohort born in Dunedin (New Zealand) in 1972/1973. Some 901 individuals (88.8%) were dentally examined at both ages. The mean number of remaining teeth and tooth surfaces fell between 26 and 32, reflecting ongoing tooth loss. The overall prevalence of caries rose from 94.9 to 96.8%, while there were greater increases in the proportion with caries-associated tooth loss (from 10.8 to 22.8%). Caries experience was greatest in the molar teeth and upper premolars, and was lowest in the lower anterior teeth. The mean crude caries increment (CCI) was 5.0 surfaces (SD 6.6); 681 (75.5%) experienced 1+ CCI, and the mean CCI among those individuals was 6.6 surfaces (SD 6.9). Substantial dental caries and tooth loss experience occur as people move from the third into the fourth decade of life.

Background

To date, longitudinal studies of medications have been confined to older adults or clinical samples, with no data from prospective studies of younger adults. The aim of the study was to examine changes in medication usage between ages 26 and 32 in a prospective study of a representative birth cohort.

Methods

Medication use during the previous 2 weeks was investigated among 960 individuals at ages 26 and 32.

Results

Nearly two-thirds took at least one medication at each age, with medication prevalence higher among women than among men. Three-quarters of those taking at least one at age 26 were doing so at 32. Over-the-counter medication prevalence increased from 35 to 43% between 26 and 32 years of age. Although the prevalence of prescribed medications decreased (from just under half to just over one-third, and from two-thirds to below half among women), there was no significant difference between the ages once hormonal contraceptives were accounted for. By 32, reduced usage of hormonal contraceptives was apparent, with one-third of age-26 users still taking these at 32. Other categories showing major changes were analgesics (increased), anti-asthma drugs (decreased), antidepressants (increased) and antiulcer drugs (increased). At 32, 82% of those taking analgesics, 85% of those taking nutrient supplements, 71% of those taking antihistamines and 33% of those taking antiulcer drugs had self-prescribed them.

Conclusion

A considerable proportion of the sample used medications by age 32, and there was considerable change between 26 and 32. The changes are likely to have been due to a mix of ageing and period effects.

Background: There is conflicting information about the relationship between asthma and socioeconomic status, with different studies reporting no, positive, or inverse associations. Most of these studies have been cross sectional in design and have relied on subjective markers of asthma such as symptoms of wheeze. Many have been unable to control adequately for potential confounding factors.

Methods: We report a prospective cohort study of approximately 1000 individuals born in Dunedin, New Zealand in 1972–3. This sample has been assessed regularly throughout childhood and into adulthood, with detailed information collected on asthma symptoms, lung function, airway responsiveness, and atopy. The prevalence of these in relation to measures of socioeconomic status were analysed with and without controls for potential confounding influences including parental history of asthma, smoking, breast feeding, and birth order using cross sectional time series models.

Results: No consistent association was found between childhood or adult socioeconomic status and asthma prevalence, lung function, or airway responsiveness at any age. Having asthma made no difference to educational attainment or socioeconomic status by age 26. There were trends to increased atopy in children from higher socioeconomic status families consistent with previous reports.

Conclusions: Socioeconomic status in childhood had no significant impact on the prevalence of asthma in this New Zealand born cohort. Generalisation of these results to other societies should be done with caution, but our results suggest that the previously reported associations may be due to confounding.

Objectives: To determine if physical and/or psychological risk factors could differentiate between subtypes of primary headache (migraine, tension-type headache (TTH), and coexisting migraine and TTH (combined)) among members of a longitudinal birth cohort study.

Methods: At age 26, the headache status of members of the Dunedin Multidisciplinary Health and Development Study (DMHDS) was determined using International Headache Society criteria. Headache history and potential physical and psychological correlates of headache were assessed. These factors included perinatal problems and injuries sustained to age 26; and behavioural, personality, and psychiatric disorders assessed between ages 5 to 21.

Results: The 1 year prevalences for migraine, TTH, and combined headache at the age of 26 were 7.2%, 11.1%, and 4.3%, respectively. Migraine was related to maternal headache, anxiety symptoms in childhood, anxiety disorders during adolescence and young adulthood, and the stress reactivity personality trait at the age of 18. TTH was significantly associated with neck or back injury in childhood (before the age of 13). Combined headache was related to maternal headache and anxiety disorder at 18 and 21 only among women with a childhood history of headache. Headache status at the age of 26 was unrelated to a history of perinatal complication, neurological disorder, or mild traumatic head injury.

Conclusions: Migraine and TTH seem to be distinct disorders with different developmental characteristics. Combined headache may also have a distinct aetiology.