Research on the correlates of physical activity (PA) and sedentary behaviour (SB) to date has used independent prediction equations for each behaviour, without considering that they are both part of the same continuum of movement. This assumption of independence might lead to inaccurate estimates because common underlying latent variables may simultaneously influence the propensity to engage in PA and SB. This study tests empirically the interdependent nature of PA and SB by comparing independent equations (current approach in the literature), and joint estimators (a novel but unexplored approach). Using Health Survey for England 2008 data, accelerometry-accessed PA and SB were separately modelled (using ordinary least squared regressions - OLS) and then jointly (using seemingly unrelated regressions -SUR). We tested for diagonality, specification, and goodness of fit.
The best fit models were the ones that allowed for interdependence of the two movement-related behaviours (rho = −0.156; p < 0.001). The SUR showed more favourable properties compared to OLS models; producing lower standard errors and more consistent and efficient coefficients. The efficiency gain was more pronounced in the SB equation (Chi2 = 92.75; p < 0.001).
Evidence from a large national population-wide accelerometry study suggests that accounting for the interdependent nature of PA and SB in prediction equations leads to more efficient modelling estimates. Further research using different samples is, however, required to fully understand the magnitude of efficiency gains accruable from using the joint estimators.
To examine the associations between socioeconomic position (SEP) and multidomain self-reported and objectively-assessed sedentary time (ST).
General population households in England.
2289 adults aged 16–96 years who participated in the 2008 Health Survey for England.
Accelerometer-measured ST, and self-reported television time, non-television leisure-time sitting and occupational sitting/standing. We examined multivariable associations between household income, social class, education, area deprivation for each SEP indicator (including a 5-point composite SEP score computed by aggregating individual SEP indicators) and each ST indicator using generalised linear models.
Accelerometry-measured total ST and occupational sitting/standing were positively associated with SEP score and most of its constituent SEP indicators, while television time was negatively associated with SEP score and education level. Area-level deprivation was largely unrelated to ST. Those in the lowest composite SEP group spent 64 (95% CIs 52 to 76) and 72 (48 to 98), fewer minutes/day in total ST and occupational sitting/standing compared to those in the top SEP group, and an additional 48 (35–60) min/day watching television (p<0.001 for linear trend). Stratified analyses showed that these associations between composite SEP score and total ST were evident only among participants who were in employment.
Occupational sitting seems to drive the positive association between SEP and total ST. Lower SEP is linked to higher TV viewing times.
EPIDEMIOLOGY; PUBLIC HEALTH; SOCIAL MEDICINE
Few studies have examined both the relative magnitude of association and the discriminative capability of multiple indicators of obesity with cardiovascular disease (CVD) mortality risk. We conducted an individual-participant meta-analysis of 9 cohort studies of men and women drawn from the British general population resulted in sample of 82,864 individuals. Body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) were measured directly. There were 6,641 deaths (1,998 CVD) during a mean of 8.1 years of follow-up. After adjustment, a one SD higher in WHR and WC was related to a higher risk of CVD mortality (HR (95% CI)): 1.15 (1.05-1.25) and 1.15 (1.04-1.27), respectively. The risk of CVD also increased linearly across quintiles of both these abdominal obesity markers with a 66% increased risk in the highest quintile of WHR. In age- and sex-adjusted models only, BMI was related to CVD mortality but not in any other analyses. No major differences were revealed in the discrimination capabilities of models with BMI, WC or WHR for cardiovascular or total mortality outcomes. In conclusion, measures of abdominal adiposity, but not BMI, were related to an increased risk of cardiovascular disease mortality. No difference was observed in discrimination capacities between adiposity markers.
body mass index; waist circumference; waist-to-hip ratio; cardiovascular disease mortality
The criterion validity of the 2008 Physical Activity and Sedentary Behavior Assessment Questionnaire (PASBAQ) was examined in a nationally representative sample of 2,175 persons aged ≥16 years in England using accelerometry. Using accelerometer minutes/day greater than or equal to 200 counts as a criterion, Spearman's correlation coefficient (ρ) for PASBAQ-assessed total activity was 0.30 (95% confidence interval (CI): 0.25, 0.35) in women and 0.20 (95% CI: 0.15, 0.26) in men. Correlations between accelerometer counts/minute of wear time and questionnaire-assessed relative energy expenditure (metabolic equivalent-minutes/day) were higher in women (ρ = 0.41, 95% CI: 0.36, 0.46) than in men (ρ = 0.32, 95% CI: 0.26, 0.38). Similar correlations were observed for minutes/day spent in vigorous activity (women: ρ = 0.39, 95% CI: 0.33, 0.46; men: ρ = 0.31, 95% CI: 0.26, 0.36) and moderate-to-vigorous activity (women: ρ = 0.42, 95% CI: 0.36, 0.48; men: ρ = 0.38, 95% CI: 0.32, 0.45). Correlations for time spent being sedentary (<100 counts/minute) were 0.30 (95% CI: 0.24, 0.35) and 0.25 (95% CI: 0.19, 0.30) in women and men, respectively. Sedentary behavior correlations showed no sex difference. The validity of sedentary behavior and total physical activity was higher in older age groups, but validity was higher in younger persons for vigorous-intensity activity. The PASBAQ is a useful and valid instrument for ranking individuals according to levels of physical activity and sedentary behavior.
accelerometry; physical activity; questionnaires; sedentary behavior; validation
With drug treatment for dementia being of limited effectiveness, the role of primary prevention, in particular the predictive value of modifiable cardiovascular disease risk factors, may warrant exploration. The evidence base is, however, characterised by discordant findings and is modest in size. Accordingly, we examined the association of modifiable cardiovascular disease risk factors with dementia death.
Design and methods
We pooled raw data from 10 UK general population-based prospective cohort studies within the context of an individual participant meta-analysis.
A total of 103,764 men and women were followed up for a mean of 8 years giving rise to 443 dementia-related deaths and 2612 cardiovascular disease deaths. Cardiovascular disease mortality was, as anticipated, associated with the full range of risk factors under study, including raised blood pressure, smoking, diabetes, physical inactivity. By contrast, dementia death was related to very few of the cardiovascular disease risk factors: of those classified as modifiable, only smoking was associated with a raised risk and higher levels of non-HDL with a lower risk.
In the present individual participant meta-analysis, there was limited evidence that cardiovascular disease risk factors were related to dementia death.
Yoga is a holistic practice that may offer several health benefits. No study has examined the prevalence, temporal trends, or correlates of yoga practice at the population level in a European country and very few such studies exist worldwide. The objective of the study is to examine the prevalence, trends and correlates of yoga practice in England between 1997 and 2008.
Analysis was conducted in early 2013 using Health Survey for England data. Independent cohorts, representative of adults living in England, were surveyed in annual cycles in 1997-1999, 2003-2004, and 2006/2008. Prevalence of yoga practice (defined as any practice in the past four weeks) was determined at each time point and multiple logistic regression was used to examine temporal trends (using 1997-1999 as reference time point) and the correlates of yoga practice. The prevalence of yoga practice was 0.46% (95% CI: 0.39%-0.52%) in 1997-1999, 0.94% (0.83%-1.06%) in 2003-2004, and 1.11% (0.95%-1.28%) in 2006/2008. Yoga participants in England were more likely to be older, female, degree educated, of non-manual social class, lower BMI, better self-rated general health, inactive occupation, and higher moderate-to-vigorous physical activity. Adjusted for age, sex, social class, and long standing illnesses, there was a significant increasing trend of yoga practice from 1997 to 2008 (2003/04 OR = 1.93, 95% CI: 1.59-2.34; 2006/08 OR = 2.19, 95% CI: 1.77-2.71).
Yoga practice has increased in popularity, though the absolute rates are still relatively low. Future population studies should more comprehensively examine the contexts, settings, styles, correlates and health benefits of yoga practice.
Yoga; Exercise; Trends; Prevalence; England
There is increasing interest in the association between sedentary behaviour and mental health, although most studies have relied solely on self-reported measures, thus making results prone to various biases. The aim was to compare associations between objectively assessed and self-reported sedentary time with mental health in adults.
Community dwelling population sample drawn from the 2008 Health Survey for England.
11 658 (self-report analysis) and 1947 (objective data) men and women.
The 12-item General Health Questionnaire was administered to assess psychological distress. Sedentary and physical activity (exposure) was objectively measured using accelerometers (Actigraph GT1M) worn around the waist during waking hours for seven consecutive days.
The highest tertile of objective sedentary time was associated with higher risk of psychological distress (multivariate adjusted OR=1.74, 95% CI 1.07 to 2.83), as was the highest tertile of self-reported total sitting time (OR=1.34, 95% CI 1.15 to 1.56). Self-reported, but not objective, moderate-to-vigorous physical activity was associated with lower risk of psychological distress. Only objective light-intensity activity was associated with lower risk of psychological distress.
Sedentary time is associated with adverse mental health.
Mental Health; Epidemiology; Public Health
Cardiorespiratory fitness (CRF) is a key predictor of chronic disease, particularly cardiovascular disease (CVD), but its assessment usually requires exercise testing which is impractical and costly in most health-care settings. Non-exercise testing cardiorespiratory fitness (NET-F)-estimating methods are a less resource-demanding alternative, but their predictive capacity for CVD and total mortality has yet to be tested. The objective of this study is to examine the association of a validated NET-F algorithm with all-cause and CVD mortality.
Methods and results
The participants were 32 319 adults (14 650 men) aged 35–70 years who took part in eight Health Survey for England and Scottish Health Survey studies between 1994 and 2003. Non-exercise testing cardiorespiratory fitness (a metabolic equivalent of VO2max) was calculated using age, sex, body mass index (BMI), resting heart rate, and self-reported physical activity. We followed participants for mortality until 2008. Two thousand one hundred and sixty-five participants died (460 cardiovascular deaths) during a mean 9.0 [standard deviation (SD) = 3.6] year follow-up. After adjusting for potential confounders including diabetes, hypertension, smoking, social class, alcohol, and depression, a higher fitness score according to the NET-F was associated with a lower risk of mortality from all-causes (hazard ratio per SD increase in NET-F 0.85, 95% confidence interval: 0.78–0.93 in men; 0.88, 0.80–0.98 in women) and CVD (men: 0.75, 0.63–0.90; women: 0.73, 0.60–0.92). Non-exercise testing cardiorespiratory fitness had a better discriminative ability than any of its components (CVD mortality c-statistic: NET-F = 0.70–0.74; BMI = 0.45–0.59; physical activity = 0.60–0.64; resting heart rate = 0.57–0.61). The sensitivity of the NET-F algorithm to predict events occurring in the highest risk quintile was better for CVD (0.49 in both sexes) than all-cause mortality (0.44 and 0.40 for men and women, respectively). The specificity for all-cause and CVD mortality ranged between 0.80 and 0.82. The net reclassification improvement of CVD mortality risk (vs. a standardized aggregate score of the modifiable components of NET-F) was 27.2 and 21.0% for men and women, respectively.
The CRF-estimating method NET-F that does not involve exercise testing showed consistent associations with all-cause and cardiovascular mortality, and it had good discrimination and excellent risk reclassification improvement. As such, it merits further attention as a practical and potentially and useful risk prediction tool.
Epidemiology; Non-exercise testing; Cardiorespiratory fitness; Cardiovascular disease; Physical activity; Health Survey for England
Television (TV) viewing has been associated with obesity although the effects of specific TV content on health and other behaviours remains unknown. We examined the association between watching sport on TV, physical activity levels, and risk of obesity.
We studied 6,733 (aged 64.9 ± 9.2 yrs) men and women from the English Longitudinal Study of Ageing, a prospective study of community dwelling older adults. Data were collected on self reported TV time and content, and physical activity. Nurses measured height and weight for the calculation of body mass index.
On average, participants reported viewing TV for 5.3 ± 4.1 hours per day and 30.3% of the sample watched sport on TV at least twice a week. There was no association between watching sport and physical activity levels. Participants that watched sports every day were at higher risk of obesity [odds ratio = 1.39, 95% CI, 1.15, 1.68) after adjustment for age, sex, smoking, alcohol, physical activity, total TV time, disability, and self-rated health.
Watching elite athletes may have no role in the promotion of physical activity in older adults, which has implications for staging large sporting events with physical activity legacy promises.
Ageing; Epidemiology; Health promotion; Obesity; Physical activity; Sedentary
Life-course socioeconomic factors may have a role in dementia aetiology but there is a current paucity of studies. Meta-analyses of individual participant data would considerably strengthen this evidence base.
To examine the association between socioeconomic status in early life and adulthood with later dementia death.
Individual participant meta-analysis of 11 prospective cohort studies (1994-2004, n = 86 508).
Leaving full-time education at an earlier age was associated with an increased risk of dementia death in women (fully adjusted hazard ratio (HR) for age ⩽14 v. age ⩾16: HR = 1.76, 95% CI 1.23-2.53) but not men. Occupational social class was not statistically significantly associated with dementia death in men or women.
Lower educational attainment in women was associated with an increased risk of dementia-related death independently of common risk behaviours and comorbidities.
Previous data indicate a rapidly increasing prevalence of obesity and overweight among English children and an emerging socioeconomic gradient in prevalence. The main aim of this study was to update prevalence trends among school-age children and assess the changing socioeconomic gradient.
A series of nationally representative household-based health surveys conducted between 1997 and 2007 in England.
15,271 white children (7880 boys) aged 5 to 10 years with measured height and weight.
Height and weight were directly measured by trained fieldworkers. Overweight (including obesity) and obesity prevalence were calculated using the international body mass index cut-offs. Socioeconomic position (SEP) score was a composite score based on income and social class. Multiple linear regression assessed the prevalence odds with time point (1997/8, 2000/1, 2002/3, 2004/5, 2006/7) as the main exposure. Linear interaction terms of time by SEP were also tested for.
There are signs that the overweight and obesity trend has levelled off from 2002/3 to 2006/7. The odds ratio (OR) for overweight in 2006/7 compared to 2002/3 was 0.99 (95% CI 0.88 to 1.11) and for obesity OR = 1.06 (0.86 to 1.29). The socioeconomic gradient has increased in recent years, particularly 2006/7. Compared to 1997/8, the 2006/7 age and sex-adjusted OR for overweight was 1.88 (1.52 to 2.33) in low SEP, 1.25 (1.04 to 1.50) in middle SEP, and 1.13 (0.86 to 1.48) in high SEP children.
Childhood obesity and overweight prevalence among school-age children in England has stabilised in recent years, but children from lower socio-economic strata have not benefited from this trend. There is an urgent need to reduce socio-economic disparities in childhood overweight and obesity.
Obesity; overweight; children; trends; England; socioeconomic status; socioeconomic position; income
Sedentary behaviour is an emerging cardiometabolic risk factor in young people. Little is known about how socioeconomic position (SEP) and sedentary behaviour are associated in children and adolescents. This study examines associations between SEP and sedentary behaviour in school-age children and adolescents.
The core sample comprised 3822 Health Survey for England 2008 participants aged 5–15 years with complete information on SEP (household income, head of household occupational social class and area deprivation) and self-reported sedentary time (television viewing and other sitting during non-school times). Accelerometer-measured total sedentary time was measured in a subsample (N=587). We examined multivariable associations between SEP (including a composite SEP score) and sedentary time using generalised linear models, adjusting for age, sex, body mass index, physical activity, accelerometer wear time and mutually adjusting for the other SEP indicators.
Participants in the highest SEP category spent 16 min/day less (95% CI 6 to 25, p=0.003) watching TV than participants in the lowest SEP category; yet they spent 7 (2 to 16, p=0.010) and 17 (5 to 29, p<0.000) min/day more in non-TV sitting and total (accelerometry-measured) sedentary time, respectively. Associations across individual SEP components varied in strength. Area deprivation was not associated with sedentary time.
Low SEP is linked with higher television times but with lower total (accelerometer-measured) sedentary time, and non-TV sitting during non-school time in children and adolescents. Associations between sedentary time and SEP differ by type of sedentary behaviour. TV viewing is not a good proxy for total sedentary time in children.
Physical Activity; Social Inequalities; Health Behaviour
To quantify the association between daily total sitting and all-cause mortality risk and to examine dose-response relationships with and without adjustment for moderate-to-vigorous physical activity.
Studies published from 1989 to January 2013 were identified via searches of multiple databases, reference lists of systematic reviews on sitting and health, and from authors’ personal literature databases. We included prospective cohort studies that had total daily sitting time as a quantitative exposure variable, all-cause mortality as the outcome and reported estimates of relative risk, or odds ratios or hazard ratios with 95% confidence intervals. Two authors independently extracted the data and summary estimates of associations were computed using random effects models.
Six studies were included, involving data from 595,086 adults and 29,162 deaths over 3,565,569 person-years of follow-up. Study participants were mainly female, middle-aged or older adults from high-income countries; mean study quality score was 12/15 points. Associations between daily total sitting time and all-cause mortality were not linear. With physical activity adjustment, the spline model of best fit had dose-response HRs of 1.00 (95% CI: 0.98-1.03), 1.02 (95% CI: 0.99-1.05) and 1.05 (95% CI: 1.02-1.08) for every 1-hour increase in sitting time in intervals between 0-3, >3-7 and >7 h/day total sitting, respectively. This model estimated a 34% higher mortality risk for adults sitting 10 h/day, after taking physical activity into account. The overall weighted population attributable fraction for all-cause mortality for total daily sitting time was 5.9%, after adjusting for physical activity.
Higher amounts of daily total sitting time are associated with greater risk of all-cause mortality and moderate-to-vigorous physical activity appears to attenuate the hazardous association. These findings provide a starting point for identifying a threshold on which to base clinical and public health recommendations for overall sitting time, in addition to physical activity guidelines.
There is mounting evidence for associations between sedentary behaviours and adverse health outcomes, although the data on occupational sitting and mortality risk remain equivocal. The aim of this study was to determine the association between occupational sitting and cardiovascular, cancer and all-cause mortality in a pooled sample of seven British general population cohorts.
The sample comprised 5380 women and 5788 men in employment who were drawn from five Health Survey for England and two Scottish Health Survey cohorts. Participants were classified as reporting standing, walking or sitting in their work time and followed up over 12.9 years for mortality. Data were modelled using Cox proportional hazard regression adjusted for age, waist circumference, self-reported general health, frequency of alcohol intake, cigarette smoking, non-occupational physical activity, prevalent cardiovascular disease and cancer at baseline, psychological health, social class, and education.
In total there were 754 all-cause deaths. In women, a standing/walking occupation was associated with lower risk of all-cause (fully adjusted hazard ratio [HR] = 0.68, 95% CI 0.52–0.89) and cancer (HR = 0.60, 95% CI 0.43–0.85) mortality, compared to sitting occupations. There were no associations in men. In analyses with combined occupational type and leisure-time physical activity, the risk of all-cause mortality was lowest in participants with non-sitting occupations and high leisure-time activity.
Sitting occupations are linked to increased risk for all-cause and cancer mortality in women only, but no such associations exist for cardiovascular mortality in men or women.
Prolonged sitting is an emerging health risk. However, multi-country comparative sitting data are sparse. This paper reports the prevalence and correlates of sitting time in 32 European countries.
Data from the Eurobarometer 64.3 study were used, which included nationally representative samples (n = 304-1,102) from 32 European countries. Face-to-face interviews were conducted during November and December 2005. Usual weekday sitting time was assessed using the International Physical Activity Questionnaire (short-version). Sitting time was compared by country, age, gender, years of education, general health status, usual activity and physical activity. Multivariable-adjusted analyses assessed the odds of belonging to the highest sitting quartile.
Data were available for 27,637 adults aged 15–98 years. Overall, mean reported weekday sitting time was 309 min/day (SD 184 min/day). There was a broad geographical pattern and some of the lowest amounts of daily sitting were reported in southern (Malta and Portugal means 194–236 min/day) and eastern (Romania and Hungary means 191–276 min/day) European countries; and some of the highest amounts of daily sitting were reported in northern European countries (Germany, Benelux and Scandinavian countries; means 407–335 min/day). Multivariable-adjusted analyses showed adults with low physical activity levels (OR = 5.10, CI95 = 4.60-5.66), those with high sitting in their main daily activity (OR = 2.99, CI95 = 2.74-3.25), those with a bad/very bad general health state (OR = 1.87, CI95 = 1.63-2.15) and higher education levels (OR = 1.48, CI95 = 1.38-1.59) were more likely to be in the highest quartile of daily sitting time. Adults within Greece (OR = 2.91, CI95 = 2.51-3.36) and Netherlands (OR = 2.56, CI95 = 2.22-2.94) were most likely to be in the highest quartile. High-sit/low-active participants comprised 10.1% of the sample. Adults self-reporting bad/very bad general health state (OR = 4.74, CI95 = 3.97-5.65), those within high sitting in their main daily activities (OR = 2.87, CI95 = 2.52-3.26) and adults aged ≥65 years (OR = 1.53, CI95 = 1.19-1.96) and were more likely to be in the high-sit/low-active group.
Weekday sitting time and its demographic correlates varied considerably across European countries, with adults in north-western European countries sitting the most. Sitting is prevalent across Europe and merits attention by preventive interventions.
Sitting; Adults; Europe; Prevalence; Correlates
Sarcopenia is associated with loss of independence and ill-health in the elderly although the causes remain poorly understood. We examined the association between two screen-based leisure time sedentary activities (daily TV viewing time and internet use) and muscle strength.
Methods and Results
We studied 6228 men and women (aged 64.9±9.1 yrs) from wave 4 (2008-09) of the English Longitudinal Study of Ageing, a prospective study of community dwelling older adults. Muscle strength was assessed by a hand grip test and the time required to complete five chair rises. TV viewing and internet usage were inversely associated with one another. Participants viewing TV ≥6hrs/d had lower grip strength (Men, B = −1.20 kg, 95% CI, −2.26, −0.14; Women, −0.75 kg, 95% CI, −1.48, −0.03) in comparison to <2hrs/d TV, after adjustment for age, physical activity, smoking, alcohol, chronic disease, disability, depressive symptoms, social status, and body mass index. In contrast, internet use was associated with higher grip strength (Men, B = 2.43 kg, 95% CI, 1.74, 3.12; Women, 0.76 kg, 95% CI, 0.32, 1.20). These associations persisted after mutual adjustment for both types of sedentary behaviour.
In older adults, the association between sedentary activities and physical function is context specific (TV viewing vs. computer use). Adverse effects of TV viewing might reflect the prolonged sedentary nature of this behavior.
Research on language and aging typically shows that language comprehension is preserved across the life span. Recent neuroimaging results suggest that this good performance is underpinned by age-related neural reorganization [e.g., Tyler, L. K., Shafto, M. A., Randall, B., Wright, P., Marslen-Wilson, W. D., & Stamatakis, E. A. Preserving syntactic processing across the adult life span: The modulation of the frontotemporal language system in the context of age-related atrophy. Cerebral Cortex, 20, 352–364, 2010]. The current study examines how age-related reorganization affects the balance between component linguistic processes by manipulating semantic and phonological factors during spoken word recognition in younger and older adults. Participants in an fMRI study performed an auditory lexical decision task where words varied in their phonological and semantic properties as measured by degree of phonological competition and imageability. Older adults had a preserved lexicality effect, but compared with younger people, their behavioral sensitivity to phonological competition was reduced, as was competition-related activity in left inferior frontal gyrus. This was accompanied by increases in behavioral sensitivity to imageability and imageability-related activity in left middle temporal gyrus. These results support previous findings that neural compensation underpins preserved comprehension in aging and demonstrate that neural reorganization can affect the balance between semantic and phonological processing.
The core of human language, which differentiates it from the communicative abilities of other species, is the set of combinatorial operations called syntax. For over a century researchers have attempted to understand how this essential function is organised in the brain. Here we combine behavioural and neuroimaging methods, with left hemisphere-damaged patients and healthy controls, to identify the pathways connecting the brain regions involved in syntactic processing. In a previous fMRI study (Tyler et al. 2010b) we established that regions of left inferior frontal cortex and left posterior middle temporal cortex were activated during syntactic processing. These clusters were used here as seeds for probabilistic tractography analyses in patients and controls, allowing us to delineate, and measure the integrity of, the white matter tracts connecting the frontal and temporal regions active for syntax. We found that structural disconnection in either of two fibre bundles - the arcuate fasciculus or the extreme capsule fibre system - was associated with syntactic impairment in patients. The results demonstrate the causal role in syntactic analysis of these two major left hemisphere fibre bundles - challenging existing views about their role in language functions, and providing a new basis for future research in this key area of human cognition.
diffusion tensor imaging; connectivity; tractography; stroke; grammar
Understanding the relationship between brain and cognition critically depends on data from brain-damaged patients since these provide major constraints on identifying the essential components of brain–behavior systems. Here we relate structural and functional fMRI data with behavioral data in 21 human patients with chronic left hemisphere (LH) lesions and a range of language impairments to investigate the controversial issue of the role of the hemispheres in different language functions. We address this issue within a dual neurocognitive model of spoken language comprehension in which core linguistic functions, e.g., syntax, depend critically upon an intact left frontotemporal system, whereas more general communicative abilities, e.g., semantics, are supported by a bilateral frontotemporal system and may recover from LH damage through normal or enhanced activity in the intact right hemisphere. The fMRI study used a word-monitoring task that differentiated syntactic and semantic aspects of sentence comprehension. We distinguished overlapping interactions between structure, neural activity, and performance using joint independent components analysis, identifying two structural–functional networks, each with a distinct relationship with performance. Syntactic performance correlated with tissue integrity and activity in a left frontotemporal network. Semantic performance correlated with activity in right superior/middle temporal gyri regardless of tissue integrity. Right temporal activity did not differ between patients and controls, suggesting that the semantic network is degenerately organized, with regions in both hemispheres able to perform similar computations. Our findings support the dual neurocognitive model of spoken language comprehension and emphasize the importance of linguistic specificity in investigations of language recovery in patients.
The production and comprehension of human language is thought to involve a network of frontal, parietal, and temporal cortical loci interconnected by two dominant white matter pathways. These two white matter bundles, often referred to as the dorsal and ventral processing tracts, are hypothesized to have markedly different language functions. The dorsal tract is thought to process phonological processing, while the ventral tract is considered to abet semantics. This proposed functional differentiation of tracts is similar to the ventral and dorsal dichotomy proposed for the visual and auditory systems. The present study evaluated this characterization of the language system in the context of various components involved in its function. Twenty-four chronic stroke patients completed a battery of 10 language tests designed to measure performance on the comprehension and production of phonology, morphology, semantics, and syntax. The patients also completed diffusion MRI scanning. Lesions were confined to the left hemisphere, but the size and location of the insult varied so that patients had damage to a single tract, both tracts, or neither tract. Individual FA maps were generated, and focal areas of hypointensity served as markers of white matter damage. Whole-brain voxel-by-voxel correlations revealed that only phonological and semantic tasks fit into the dual-stream model, while syntax and morphology involved both pathways. ROI analyses of the arcuate fascicle and extreme capsule supported this finding. These data suggest that natural language function is more likely to reflect a synergistic system rather than a segregated dual-stream system.
C-reactive protein (CRP) is associated with the risk of cardiovascular disease (CVD); whether the effects are modified by diabetes status still is unclear. This study investigated these issues and assessed the added value of CRP to predictions.
RESEARCH DESIGN AND METHODS
Participants were drawn from representative samples of adults living in England and Scotland. Cox proportional hazards regression models were used to relate baseline plasma CRP with all-cause and CVD mortality during follow-up in men and women with and without diabetes. The added value of CRP to the predictions was assessed through c-statistic comparison and relative integrated discrimination improvement.
A total of 25,979 participants (4.9% with diabetes) were followed for a median of 93 months, during which period there were 2,767 deaths (957 from CVD). CRP (per SD loge) was associated with a 53% (95% CI 43–64) and 43% (38–49) higher risk of cardiovascular and all-cause mortality, respectively. These associations were log linear and did not differ according to diabetes status (both P ≥ 0.08 for interaction), sex, and other risk factors. Adding CRP to conventional risk factors improved predictions overall and separately by diabetes status but not for CVD mortality, although such improvements only were marginal based on several discrimination statistics.
The association between CRP and CVD was similar across diabetes status, and the effects are broadly similar across levels of other conventional risk factors.
Prospective studies report associations between indicators of time spent sitting and obesity risk. Most studies use a single indicator of sedentary behavior and are unable to clearly identify whether sedentary behavior is a cause or a consequence of obesity.
To investigate cross-sectional and prospective associations between multiple sitting time indicators and obesity and examine the possibility of reverse causality.
Using data from the Whitehall II cohort, multiple logistic models were fitted to examine associations between prevalent obesity (BMI ≥30) at Phase 5 (1997–1999), and incident obesity between Phases 5 and 7 (2003–2004) across four levels of five sitting exposures (work sitting, TV viewing, non-TV leisure-time sitting, leisure-time sitting, and total sitting). Using obesity data from three prior phases (1985–1988, 1991–1993; and recalled weight at age 25 years), linear regression models were fitted to examine the association between prior obesity and sitting time at Phase 5. Analyses were conducted in 2012.
None of the sitting exposures were associated with obesity either cross-sectionally or prospectively. Obesity at one previous measurement phase was associated with a 2.43-hour/week (95% CI=0.07, 4.78) increase in TV viewing; obesity at three previous phases was associated with a 7.42-hour/week (95% CI=2.7, 12.46) increase in TV-viewing hours/week at Phase 5.
Sitting time was not associated with obesity cross-sectionally or prospectively. Prior obesity was prospectively associated with time spent watching TV per week but not other types of sitting.
Cognitive models claim that spoken words are recognized by an optimally efficient sequential analysis process. Evidence for this is the finding that nonwords are recognized as soon as they deviate from all real words (
Marslen-Wilson 1984), reflecting continuous evaluation of speech inputs against lexical representations. Here, we investigate the brain mechanisms supporting this core aspect of word recognition and examine the processes of competition and selection among multiple word candidates. Based on new behavioral support for optimal efficiency in lexical access from speech, a functional magnetic resonance imaging study showed that words with later nonword points generated increased activation in the left superior and middle temporal gyrus (Brodmann area [BA] 21/22), implicating these regions in dynamic sound-meaning mapping. We investigated competition and selection by manipulating the number of initially activated word candidates (competition) and their later drop-out rate (selection). Increased lexical competition enhanced activity in bilateral ventral inferior frontal gyrus (BA 47/45), while increased lexical selection demands activated bilateral dorsal inferior frontal gyrus (BA 44/45). These findings indicate functional differentiation of the fronto-temporal systems for processing spoken language, with left middle temporal gyrus (MTG) and superior temporal gyrus (STG) involved in mapping sounds to meaning, bilateral ventral inferior frontal gyrus (IFG) engaged in less constrained early competition processing, and bilateral dorsal IFG engaged in later, more fine-grained selection processes.
spoken word recognition; lexical competition; lexical selection; inferior frontal gyrus; cohort model