Intelligence in early adulthood and subsequent risk of unintentional injury over two decades: cohort study of 1 109 475 Swedish men

Subjective evaluations of self and others' driving behaviors: A comparative study involving data from drivers in Japan, China, and Vietnam

INTRODUCTION

This study explored the influence of personal attributes on subjectively-reported aggressive driving behaviors, with an emphasis on the inter-influences between subjectively-reported aggressive driving behaviors between self and other individuals. To determine this, a survey was conducted comprising participants' socio-demographic data, information on their history with automotive accidents, and subjective scales to report on the driving behaviors between self and others. More specifically, a four-factor shortened version of the Manchester Driver Behavior Questionnaire was used to collect data on the aberrant driving behaviors of "self" and "others."

METHOD

Participants were recruited from three countries, namely, Japan (1,250 responses), China (1,250), and Vietnam (1,000). This study only considered the "aggressive violations' factor," which was referred to as self-aggressive driving behaviors (SADB) and others' aggressive driving behaviors (OADB). After collecting the data, univariate and bivariate multiple regression models were employed to better understand the response patterns from both scales.

RESULTS

This study found that accident experience had the strongest influence on the reporting of aggressive driving behaviors (followed by education level). However, variation in countries was also found between both the rate of engagement in aggressive driving behavior and its recognition. In this study, highly educated Japanese drivers tended to evaluate others as safe, whereas highly educated Chinese drivers tended to evaluate others as aggressive. This discrepancy can likely be attributed to cultural norms and values. Meanwhile, evaluations from Vietnamese drivers seemed to differ depending on whether they drove cars or bikes, with additional influences as a result of the driving frequency. Furthermore, this study found that it was most difficult to explain the driving behaviors on the "other" scale reported by Japanese drivers.

PRACTICAL APPLICATIONS

These findings can aid policymakers and planners to develop road safety measures that reflect the behaviors of drivers in their respective countries.

Visual Acuity and the Risk of Cycling Injuries: Register-Based Cohort Study From Adolescence to Middle-age

BACKGROUND

Cycling is increasingly encouraged in many countries as an inexpensive and healthy choice of transportation. Operating any vehicle on the road requires high visual acuity, but few studies to our knowledge have examined the association between vision and cycling injuries.

METHODS

We examined whether poorer visual acuity is associated with increased risk of fatal and nonfatal cycling injuries. We used prospectively recorded register data for 691,402 men born between 1970 and 1992 in Sweden. We followed these men from an average age of 18 years, when visual acuity was assessed during the conscription assessment, to age 45 at the latest. We identified fatal and nonfatal cycling and car injuries using Patient and Cause of Death registers. Cox regression models were used to estimate hazard ratios and 95% confidence intervals.

RESULTS

Based on visual acuity for the eye with the best vision, moderately impaired acuity 0.9 to 0.6 when wearing refractive correction was associated with increased risk for cycling injuries (hazard ratio = 1.44 [95% confidence interval = 1.16, 1.79]) compared with unimpaired vision (uncorrected visual acuity 1.0) and after adjustment for a wide range of potential confounders. This association remained consistent across various sensitivity analyses. Visual acuity was not associated with car injury risk.

CONCLUSIONS

In this cohort study, poorer vision was specifically associated with a higher rate of cycling injuries.

Assessment of Posttraumatic Stress Disorder and Educational Achievement in Sweden

IMPORTANCE

Posttraumatic stress disorder (PTSD) has been associated with impaired educational performance. Previous studies on the disorder could not control for important measured and unmeasured confounders.

OBJECTIVE

To prospectively investigate the association between PTSD and objective indicators of educational attainment across the life span, controlling for familial factors shared by full siblings, psychiatric comorbidity, and general cognitive ability.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study included 2 244 193 individuals born in Sweden between January 1, 1973, and December 31, 1997, who were followed-up until December 31, 2013. Clusters of full siblings were used to account for familial factors. Data analyses were conducted between December 2018 and May 2020.

EXPOSURE

International Classification of Diseases, Ninth Revision and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnoses of PTSD in the Swedish National Patient Register.

MAIN OUTCOMES AND MEASURES

Eligibility to access upper secondary education after finishing compulsory education, finishing upper secondary education, starting a university degree, and finishing a university degree.

RESULTS

Of the final cohort of 2 244 193 individuals (1 151 414 [51.3%] men) included in the analysis, 1 425 326 were assessed for finishing compulsory education (919 with PTSD), 2 001 944 for finishing upper secondary education (2013 with PTSD), and 1 796 407 and 1 356 741 for starting and finishing a university degree (2243 and 2254 with PTSD, respectively). Posttraumatic stress disorder was associated with lower odds of achieving each of the educational milestones during the study period, including 82% lower odds of finishing compulsory education (adjusted odds ratio [aOR], 0.18; 95% CI, 0.15-0.20), 87% lower odds of finishing upper secondary education (aOR, 0.13; 95% CI, 0.12-0.14), 68% lower odds of starting a university degree (aOR, 0.32; 95% CI, 0.28-0.35), and 73% lower odds of finishing a university degree (aOR, 0.27; 95% CI, 0.23-0.31). Estimates in the sibling comparison were attenuated (aOR range, 0.22-0.53) but remained statistically significant. Overall, excluding psychiatric comorbidities and adjusting for the successful completion of the previous milestone and general cognitive ability did not statistically significantly alter the magnitude of the associations.

CONCLUSIONS AND RELEVANCE

Posttraumatic stress disorder was associated with educational impairment across the life span, and the associations were not entirely explained by shared familial factors, psychiatric comorbidity, or general cognitive ability. This finding highlights the importance of implementing early trauma-informed interventions in schools and universities to minimize the long-term socioeconomic consequences of academic failure in individuals with PTSD.

Impact of urbanization factors on mortality due to unintentional injuries using panel data regression model and spatial-temporal analysis

Unintentional injuries pose a great risk for human health in China. Few studies have focused on unintentional injuries at national level from urbanization perspective. The panel data of mortality rate of transportation accidents (TA), fall and drowning and sinking (DS) is investigated, and urbanization development index is collected. Global Moran's I and linear regression of panel data are applied to determine the spatial distribution and spatial influencing factors of unintentional injuries. The results are the following: (1) The unintentional injury such as TA, fall, and DS shows clear non-uniformity of spatial distribution and relative immobility through time. (2) A 10,000 tons increase in SO₂ emission amount (SO₂ EA) and emission of smoke and dust (ESD) can result in 15.7 and 12.5 increases in TA death in eastern region, respectively. Meanwhile, A 10,000 tons increase in NO_x emission amount can cause 15.1 increase in TA death in western region. For every 100 billion yuan increase in GDP, the fall death can reduce by 8.4 in central region. One bed increase in number of hospital beds per 10,000 population (NHBP) is favorable for decreasing in fall death by 16.7 in eastern region. However, increase in number of workers enjoying industrial injury (NEWII) does not reduce the fall death in eastern region. (3) For every 1 ten thousand people increase in number of students in ordinary high schools (NSOHS) is conductive to reducing DS death by 7.8 in the western region. Our findings show that there exist spatial differences for urbanization influencing TA, fall, and DS death in eastern, western, and central regions. This study is expected to provide a reference for unintentional injuries control in those three regions.

Association between intelligence quotient and disability: The role of socioeconomic status

BACKGROUND

No study has investigated the association between intelligence quotient (IQ) and disability (i.e., difficulties in activities of daily living [ADL] or instrumental activities of daily living [IADL]) in the general population.

OBJECTIVE

The goal of this nationally representative study was to analyse the potential IQ-disability association in England and identify influential factors in this association.

METHODS

Cross-sectional data were analyzed from the 2007 Adult Psychiatric Morbidity Survey (n=6872). IQ was assessed by using the National Adult Reading Test, which consists of a list of 50 words and is scored by counting the number of errors in reading the words aloud. Disability was defined as difficulties in at least 1 of the 7 domains of ADL and IADL. Regression and mediation analyses were conducted to analyze the association between IQ and disability and identify potential factors involved in this relationship, estimating odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Among the 6872 participants, the mean (SD) age was 46.9 (18.9) years; 51.8% were women. The prevalence of disability increased from 27.7% with IQ 120-129 to 51.0% with IQ 70-79. After adjusting for sex, age and ethnicity, as compared with IQ 120-129, with IQ 110-119, 100-109, 90-99, 80-89, and 70-79, the probability of disability was increased (OR 1.22 [95% CI 1.01-1.48], 1.42 [1.16-1.72], 1.86 [1.54-2.25], 2.41 [1.92-3.03], and 4.71 [3.56-6.17], respectively). In addition, we found a positive association between a 1-SD decrease in IQ and disability (OR 1.53, 95% CI 1.43-1.63). Finally, income (mediated percentage 26.9%), social class (18.0%) and education (11.6%) strongly affected the IQ-disability association, and these socioeconomic factors collectively explained 37.1% of the association.

CONCLUSIONS

Low IQ was positively associated with disability in England, and socioeconomic status explained more than one-third of this relationship.

Association of change in cognitive function from early adulthood to middle age with risk of cause-specific mortality: the Vietnam Experience Study

BACKGROUND

Studies with single baseline measurements of cognitive function consistently reveal inverse relationships with mortality risk. The relation of change in functioning, particularly from early in the life course, which may offer additional insights into causality, has not, to the best of our knowledge, been tested.

AIMS

To examine the association of change in cognition between late adolescence and middle age with cause-specific mortality using data from a prospective cohort study.

METHODS

The analytical sample consisted of 4289 former US male military personnel who were administered the Army General Technical Test in early adulthood (mean age 20.4 years) and again in middle age (mean age 38.3 years).

RESULTS

A 15-year period of mortality surveillance subsequent to the second phase of cognitive testing gave rise to 237 deaths. Following adjustment for age, a 10-unit increase in cognitive function was related to a reduced risk of death from all causes (HR 0.84; 95% CI 0.75 to 0.93) and cardiovascular disease (HR 0.78; 95% CI 0.64 to 0.95) but not from all cancers (HR 1.14; 95% CI 0.88 to 1.47) nor injury (HR 1.02; 95% CI 0.81 to 1.29). Adjustment for markers of socioeconomic status in middle age resulted in marked attenuation in the magnitude of these associations and statistical significance at conventional levels was lost in all analyses.

CONCLUSIONS

In the present study, the apparent link between increased cognition and mortality was mediated by socioeconomic status.

Childhood IQ and mortality during 53 years' follow-up of Swedish men and women

BACKGROUND

The association between childhood cognitive ability measured with IQ tests and mortality is well documented. However, studies on the association in women are few and conflicting, and the mechanisms underlying the association are unclear.

METHODS

Data on IQ were collected at school at age 13 among 19 919 men and women born in 1948 and 1953. Information on childhood socioeconomic position, the participants' socioeconomic and social circumstances in middle age and mortality up to 2013 was collected through national registers.

RESULTS

Lower IQ was associated with an increased risk of all-cause mortality among men (1070 cases, HR 1.31, 95% CI 1.23 to 1.39 for one SD decrease in IQ) and among women (703 cases, HR 1.16, 95% CI 1.08 to 1.25). IQ was associated with mortality from several causes of death in men, and cancer and cardiovascular disorder mortality in women. Adjustment for socioeconomic factors in childhood and, in particular, in adulthood attenuated the associations considerably in men and near completely in women.

CONCLUSION

Lower IQ was associated with an increased risk of mortality in men and women. The explanatory effects of socioeconomic factors in adulthood suggest that they constitute an important pathway in the association between IQ and mortality, especially in women.

Acne in late adolescence and risk of prostate cancer

Accumulating evidence suggest that Propionibacterium acnes may play a role in prostate carcinogenesis, but data are so far limited and inconclusive. The aim of this population-based cohort study was therefore to test whether presence of acne vulgaris during late adolescence is associated with an increased risk of prostate cancer later in life. We identified a large cohort of young men born in Sweden between 1952 and 1956, who underwent mandatory assessment for military conscription around the age of 18 (n = 243,187). Test information along with health data including medical diagnoses at time of conscription was available through the Swedish Military Conscription Register and the National Patient Register. The cohort was followed through linkages to the Swedish Cancer Register to identify the occurrence of prostate cancer until December 31, 2009. We used Cox regression to calculate adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between acne in adolescence and prostate cancer risk. A total of 1,633 men were diagnosed with prostate cancer during a median follow-up of 36.7 years. A diagnosis of acne was associated with a statistically significant increased risk for prostate cancer (adjusted HR: 1.43 95%; CI: 1.06-1.92), particularly for advanced stage disease (HR: 2.37 95%; CI 1.19-4.73). A diagnosis of acne classified as severe conferred a sixfold increased risk of prostate cancer (HR: 5.70 95% CI 1.42-22.85). Data from this large prospective population-based cohort add new evidence supporting a role of P. acnes infection in prostate cancer.

Does gender moderate the association between intellectual ability and accidental injuries? Evidence from the 1953 Stockholm Birth Cohort study

In this paper, we test for gender differences in the effects of intellectual ability on accidental injury risks using longitudinal data from the 1953 Stockholm Birth Cohort study (n=14,294). Intellectual ability was measured using IQ tests issued during a school survey at age ∼13, and outcome and covariate data was collected via record linkage to population and health registers, following the cohort from childhood to 55 years of age. We used ICD codes to identify accidental injuries resulting in hospital admissions and deaths, and shared frailty models to quantify the effects of IQ, while allowing for within-individual dependencies and recurrent events. The models included tests for the moderating effects of gender, as well as childhood family variables (parental socioeconomic status), and cohort member mediators (highest achieved education, socioeconomic status and income at the time of the event). The results indicate an inverse association between childhood IQ and subsequent accidental injury events, where 1 SD decrease in IQ implies a 17.8% increase in injury risk. We also found evidence that gender moderates this relationship, where the effect size was twice as large for men than for women (21.8% vs 9.3% per 1 SD decrease). Adult socioeconomic status can explain roughly half of the observed association. Potential explanations for these results are discussed.

Characteristics in childhood and adolescence associated with future multiple sclerosis risk in men: cohort study

Background and purpose

Associations with multiple sclerosis (MS) of living conditions in childhood and characteristics in adolescence including physical fitness, cognitive function and psychological stress resilience were investigated.

Methods

A cohort of male Swedish residents born 1952–1956 who were included in the Swedish Military Conscription Register was used to create a nested case−control study comprising 628 MS cases and 6187 controls matched on birth year, county of residence and vital status at time of diagnosis. Conscription examination records were linked with other national register data. Conditional logistic regression was used to evaluate associations with MS subsequent to the conscription examination.

Results and conclusions

Men with MS were less likely to be from more crowded households in childhood (>two persons per room) with an adjusted odds ratio of 0.67 (95% confidence interval 0.51–0.86, P = 0.023). They had lower physical working capacity in adolescence with adjusted odds ratio of 0.94 (95% confidence interval 0.89–0.99, P = 0.026). Cognitive function and stress resilience scores displayed no significant differences between cases and controls. Parental occupation in childhood and body mass index in adolescence were not associated with future MS risk. The inverse association of MS risk with higher levels of household crowding may reflect environmental factors such as the pattern of exposure to microorganisms. Lower physical fitness in men at MS risk may indicate a protective effect of exercise or could be due to prodromal disease activity, although there was no association with cognitive function. Poor psychological stress resilience (and thus risk of chronic stress arousal) was not associated with MS.

Low IQ has become less important as a risk factor for early disability pension. A longitudinal population-based study across two decades among Swedish men

BACKGROUND

Low IQ has been shown to be an important risk factor for disability pension (DP) but whether the importance has changed over time remains unclear. It can be hypothesised that IQ has become more important for DP over time in parallel with a more demanding working life. The aim of this study was to investigate the relative risk of low IQ on the risk of DP before age 30 between 1971 and 2006.

METHODS

This study covered the entire Swedish male population born between 1951 and 1976, eligible for military conscription. Information about the study subjects was obtained by linkage of national registers. Associations between IQ and DP over time were analysed by descriptive measures (mean values, proportions, etc) and by Cox proportional hazards regressions. Analyses were adjusted for educational level.

RESULTS

The cohort consisted of 1 229 346 men. The proportion that received DP before the age of 30 increased over time, from 0.68% in the cohort born between 1951 and 1955 to 0.95% in the cohort born between 1971 and 1976. The relative risk of low IQ (adjusted for education) in relation to high IQ decreased from 5.68 (95% CI 4.71 to 6.85) in the cohort born between 1951 and 1955 to 2.62 (95% CI 2.25 to 3.05) in the cohort born between 1971 and 1976.

CONCLUSIONS

Our results gave no support to the idea that the importance of low IQ for the risk of DP has increased in parallel with increasing demands in working life. In fact, low IQ has become less important as a risk factor for DP compared with high IQ between the early 1970s and 1990s. An increased educational level over the same time period is likely to be part of the explanation.

Stress resilience in male adolescents and subsequent stroke risk: cohort study

OBJECTIVE

Exposure to psychosocial stress has been identified as a possible stroke risk, but the role of stress resilience which may be relevant to chronic exposure is uncertain. We investigated the association of stress resilience in adolescence with subsequent stroke risk.

METHODS

Register-based cohort study. Some 237 879 males born between 1952 and 1956 were followed from 1987 to 2010 using information from Swedish registers. Cox regression estimated the association of stress resilience with stroke, after adjustment for established stroke risk factors.

RESULTS

Some 3411 diagnoses of first stroke were identified. Lowest stress resilience (21.8%) compared with the highest (23.7%) was associated with increased stroke risk, producing unadjusted HR (with 95% CIs) of 1.54 (1.40 to 1.70). The association attenuated slightly to 1.48 (1.34 to 1.63) after adjustment for markers of socioeconomic circumstances in childhood; and after further adjustment for markers of development and disease in adolescence (blood pressure, cognitive function and pre-existing cardiovascular disease) to 1.30 (1.18 to 1.45). The greatest reduction followed further adjustment for markers of physical fitness (BMI and physical working capacity) in adolescence to 1.16 (1.04 to 1.29). The results were consistent when stroke was subdivided into fatal, ischaemic and haemorrhagic, with higher magnitude associations for fatal rather than non-fatal, and for haemorrhagic rather than ischaemic stroke.

CONCLUSIONS

Stress susceptibility and, therefore, psychosocial stress may be implicated in the aetiology of stroke. This association may be explained, in part, by poorer physical fitness. Effective prevention might focus on behaviour/lifestyle and psychosocial stress.

Association of paternal IQ in early adulthood with offspring mortality and hospital admissions for injuries: a cohort study of 503 492 Swedish children

BACKGROUND

Higher intelligence (IQ) has been related to a lower risk of mortality and hospital admissions for injuries, but little is known about the effect of parental IQ on offspring outcomes. We explored associations of paternal IQ with mortality and hospitalisations for injuries from all external causes in offspring.

METHODS

A cohort of 503 492 Swedish children under 5 years of age with information on paternal IQ was obtained by record linkage of national registers. HR with 95% CIs were estimated using Cox regression.

RESULTS

There was some evidence that paternal IQ was inversely associated with total and external-cause mortality in offspring, although the effects were modest and disappeared when controlling for parents' socioeconomic position (SEP). The only robust gradient was found between paternal IQ and hospital admissions for injuries (HRper 1-SD increase in IQ 0.93, 95% CI 0.92 to 0.94; p<0.001), which was slightly attenuated but retained statistical significance after adjustment for SEP (0.95, 95% CI 0.94 to 0.97; p<0.001).

CONCLUSIONS

Children to fathers with lower IQ may have an increased risk of injury by external causes. Messages on family safety and injury prevention might be tailored according to parental cognitive abilities.

Reaction time and incident cancer: 25 years of follow-up of study members in the UK Health and Lifestyle Survey

OBJECTIVES

To investigate the association of reaction time with cancer incidence.

METHODS

6900 individuals aged 18 to 94 years who participated in the UK Health and Lifestyle Survey in 1984/1985 and were followed for a cancer registration for 25 years.

RESULTS

Disease surveillance gave rise to 1015 cancer events from all sites. In general, there was essentially no clear pattern of association for either simple or choice reaction time with cancer of all sites combined, nor specific malignancies. However, selected associations were found for lung cancer, colorectal cancer and skin cancer.

CONCLUSIONS

In the present study, reaction time and its components were not generally related to cancer risk.

Predicting self-reported violations among novice license drivers using pre-license simulator measures

Novice drivers are overrepresented in crash statistics and there is a clear need for remedial measures. Driving simulators allow for controlled and objective measurement of behavior and might therefore be a useful tool for predicting whether someone will commit deviant driving behaviors on the roads. However, little is currently known about the relationship between driving-simulator behavior and on-road driving behavior in novice drivers. In this study, 321 drivers, who on average 3.4 years earlier had completed a pre-license driver-training program in a medium-fidelity simulator, responded to a questionnaire about their on-road driving. Zero-order correlations showed that violations and speed in the simulator were predictive of self-reported on-road violations. This relationship persisted after controlling for age, gender, mileage, and education level. Respondents with a higher number of violations, faster speed, and lower number of errors in the simulator reported completing fewer hours of on-road lessons before their first on-road driving test. The results add to the literature on the predictive validity of driving simulators, and can be used to identify at-risk drivers early in a driver-training program.

Mortality following unemployment during an economic downturn: Swedish register-based cohort study

OBJECTIVE

To investigate if unemployment during an economic downturn is associated with mortality, even among men with markers of better health (higher cognitive function scores and qualifications), and to assess whether the associations vary by age at unemployment.

DESIGN

Longitudinal register-based cohort study.

SETTING

Study entry was in 1990 and 2001 when Sweden was entering periods of significant economic contraction.

PARTICIPANTS

A representative sample of men from the general population (n=234 782) born between 1952 and 1956 who participated in military conscription examinations. Men in receipt of disability or sickness benefit at study entry were excluded.

MAIN OUTCOME MEASURE

All-cause mortality.

RESULTS

Unemployment compared with employment in 1991 (ages 34-38 years) produced adjusted HRs (with 95% CIs) for all-cause mortality (3651 deaths) during follow-up to 2001 and after stratification by education of 2.35 (1.99 to 2.76) for compulsory education, 2.25 (1.97 to 2.58) for up to 3 years postcompulsory education and 1.90 (1.40 to 2.57) for more than 3 years postcompulsory education. When unemployment was compared with employment in 2001 (ages 45-49 years) with follow-up to 2010, the pattern of mortality risk (4271 deaths) stratified by education was reversed, producing adjusted HRs of 2.81 (2.47 to 3.21) for compulsory education, 2.87 (2.58 to 3.19) for up to 3 years postcompulsory education and 3.44 (2.78 to 4.25) for more than 3 years postcompulsory education. Interaction testing confirmed effect modification by age/period (p=0.003). The degree of gradient reversal was slightly less pronounced after stratification by cognitive function but produced a similar pattern of results (p=0.004).

CONCLUSIONS

Unemployment at older ages is associated with greater mortality risk than at younger ages, with the greatest relative increase in risk among men with markers of better health, suggesting the greater vulnerability of all older workers to unemployment-associated exposures.

Influence of maternal and paternal IQ on offspring health and health behaviours: evidence for some trans-generational associations using the 1958 British birth cohort study

PURPOSE

Individuals scoring poorly on tests of intelligence (IQ) have been reported as having increased risk of morbidity, premature mortality, and risk factors such as obesity, high blood pressure, poor diet, alcohol and cigarette consumption. Very little is known about the impact of parental IQ on the health and health behaviours of their offspring.

METHODS

We explored associations of maternal and paternal IQ scores with offspring television viewing, injuries, hospitalisations, long standing illness, height and BMI at ages 4 to 18 using data from the National Child Development Study (1958 birth cohort).

RESULTS

Data were available for 1446 mother-offspring and 822 father-offspring pairs. After adjusting for potential confounding/mediating factors, the children of higher IQ parents were less likely to watch TV (odds ratio (95% confidence interval) for watching 3+ vs. less than 3hours per week associated with a standard deviation increase in maternal or paternal IQ: 0.75 (0.64, 0.88) or 0.78 (0.64, 0.95) respectively) and less likely to have one or more injuries requiring hospitalisation (0.77 (0.66, 0.90) or 0.72 (0.56, 0.91) respectively for maternal or paternal IQ).

CONCLUSIONS

Children whose parents have low IQ scores may have poorer selected health and health behaviours. Health education might usefully be targeted at these families.