Low childhood IQ and early adult mortality: the role of explanatory factors in the 1958 British Birth Cohort

Life-Course Pathways to Exceptional Longevity: Evidence From the Lothian Birth Cohort of 1921

BACKGROUND

Longevity, a hallmark of successful aging, is a multifactorial trait with influences from birth onwards. However, limited evidence exists on the pathways linking diverse life-course exposures to longevity, especially within a single cohort.

METHODS

We investigated associations between life-course factors and longevity among community-dwelling adults aged 79 (N = 547) from the Lothian Birth Cohort 1921 with a mortality follow-up of 24 years. Cox proportional hazards and structural equation (path) models were used to explore how factors from early life (social class, childhood intelligence quotient [IQ], education), midlife (social class), and later life (health, lifestyle, psychosocial well-being), as well as sex, personality, and apolipoprotein E e4 status, influence survival time in days.

RESULTS

During follow-up (1999-2023), 538 participants (98%) died (mean age of death = 89.3 years) and 9 survived (mean age = 101.6 years). Factors associated with lower mortality risk in the multivariable Cox model were higher cognitive function (hazard ratio [HR] = 0.72; 95% confidence interval [CI]: 0.59-0.88), better physical function (HR = 0.61; 95% CI: 0.44-0.85), and greater physical activity (HR = 0.81; 95% CI: 0.71-0.92), while history of cancer was associated with higher mortality risk (HR = 1.84; 95% CI: 1.22-2.77). The life-course path model identified the same direct predictors, with additional contributions from female sex and nonsmoking status, to greater longevity. Early- and midlife factors (IQ, education, social class), and emotional stability, conscientiousness, and female sex, were indirectly and positively associated with survival trajectories via multiple dimensions of adult health.

CONCLUSIONS

In understanding why people live to very old ages it is necessary to consider factors from throughout the life course, and to include demographic, psychosocial, and health variables.

Birth weight and long-term risk of mortality among US men and women: Results from three prospective cohort studies

Background

Weight at birth has been associated with the development of various adult diseases, but its association with mortality remains unclear.

Methods

We included 22,389 men from the Health Professionals Follow-up Study (1994-2018) and 162,231 women from the Nurses' Health Study (1992-2018) and the Nurses' Health Study II (1991-2019). The hazard ratios (HRs) of mortality according to birth weight were estimated by Cox proportional hazards regression models with adjustment for potential confounders.

Findings

Compared to women reporting a birth weight of 3.16-3.82 kg, the pooled HRs for all-cause mortality were 1.13 (95% CI, 1.08 to 1.17), 0.99 (95% CI, 0.96 to 1.02), 1.04 (95% CI, 1.00 to 1.08), and 1.03 (95% CI, 0.96 to 1.10), respectively, for women with a birth weight of <2.5, 2.5-3.15, 3.83-4.5, and >4.5 kg. In cause-specific mortality analyses, women reporting birth weight >4.5 kg had a higher risk of cancer mortality (HR=1.15, 95% CI: 1.00 to 1.31), whereas women with a birth weight <2.5 kg had an elevated risk of mortality from cardiovascular diseases (HR=1.15; 95% CI, 1.05 to 1.25) and respiratory diseases (HR=1.35; 95% CI, 1.18 to 1.54). Birth weight was unrelated to all-cause mortality among men, but cause-specific mortality analyses showed an inverse association with cardiovascular disease mortality and a positive association with cancer mortality (p for linear trend = 0.012 and 0.0039, respectively).

Interpretation

low birth weight was associated with a greater risk of cardiovascular and respiratory disease mortality among women, while large birth weight was associated with a greater cancer mortality risk in both men and women.

Funding

The National Institutes of Health grants U01-HL145386, U01-CA176726, R01-HL034594, R01-HL088521, UM-CA186107, P01-CA87969, R01-CA49449, R01-CA67262, U01-HL145386, U01-CA167552, R01-HL35464, and R24-ES028521-01 support this study.

Neonatal Docosahexaenoic Acid in Preterm Infants and Intelligence at 5 Years

BACKGROUND

Docosahexaenoic acid (DHA) is a component of neural tissue. Because its accretion into the brain is greatest during the final trimester of pregnancy, infants born before 29 weeks' gestation do not receive the normal supply of DHA. The effect of this deficiency on subsequent cognitive development is not well understood.

METHODS

We assessed general intelligence at 5 years in children who had been enrolled in a trial of neonatal DHA supplementation to prevent bronchopulmonary dysplasia. In the previous trial, infants born before 29 weeks' gestation had been randomly assigned in a 1:1 ratio to receive an enteral emulsion that provided 60 mg of DHA per kilogram of body weight per day or a control emulsion from the first 3 days of enteral feeds until 36 weeks of postmenstrual age or discharge home, whichever occurred first. Children from 5 of the 13 centers in the original trial were invited to undergo assessment with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) at 5 years of corrected age. The primary outcome was the full-scale intelligence quotient (FSIQ) score. Secondary outcomes included the components of WPPSI.

RESULTS

A total of 1273 infants underwent randomization in the original trial; of the 656 surviving children who had undergone randomization at the centers included in this follow-up study, 480 (73%) had an FSIQ score available - 241 in the DHA group and 239 in the control group. After imputation of missing data, the mean (±SD) FSIQ scores were 95.4±17.3 in the DHA group and 91.9±19.1 in the control group (adjusted difference, 3.45; 95% confidence interval, 0.38 to 6.53; P = 0.03). The results for secondary outcomes generally did not support that obtained for the primary outcome. Adverse events were similar in the two groups.

CONCLUSIONS

In infants born before 29 weeks' gestation who had been enrolled in a trial to assess the effect of DHA supplementation on bronchopulmonary dysplasia, the use of an enteral DHA emulsion until 36 weeks of postmenstrual age was associated with modestly higher FSIQ scores at 5 years of age than control feeding. (Funded by the Australian National Health and Medical Research Council and Nu-Mega Ingredients; N3RO Australian New Zealand Clinical Trials Registry number, ACTRN12612000503820.).

Risk of mortality for small newborns in Brazil, 2011-2018: A national birth cohort study of 17.6 million records from routine register-based linked data

BACKGROUND

Preterm birth (<37 weeks), low birth weight (LBW,<2500g), and small for gestational age (SGA,<10th centile of birth weight for gestational age and sex) are markers of newborn vulnerability with a high risk of mortality. We estimated the prevalence of phenotypes combining these three markers and quantified the mortality risk associated with them.

METHODS

Population-based cohort study using routine register-based linked data on all births and deaths in Brazil from January 1, 2011, to December 31, 2018. We estimated the prevalence of preterm, LBW, and SGA individually and for phenotypes combining these characteristics. The mortality risk associated with each phenotype: early neonatal, late neonatal, neonatal, post-neonatal, infant, 1-4 years, and under five years was quantified using mortality rates and hazard ratios (HRs) with 95% confidence interval (CI) were estimated using Cox proportional hazard models.

FINDINGS

17,646,115 live births were included. Prevalence of preterm birth, LBW and SGA were 9.4%, 9.6% and 9.2%, respectively. Neonatal mortality risk was 16-fold (HR=15.9; 95% CI:15.7-16.1) higher for preterm compared to term, 3 times higher (HR=3.4; (95% CI:3.3-3.4) for SGA compared to adequate for gestational age (AGA), and >25 times higher for LBW (HR=25.8; (95% CI:25.5-26.1) compared to normal birth weight (NBW). 18% of all live births were included in one of the small vulnerable newborn phenotypes. Of those 8.2% were term-SGA (4.7%NBW, 3.5%LBW), 0.6% were term-AGA-LBW, 8.3% preterm-AGA (3.8%NBW, 4.5%LBW) and 1.0% preterm-SGA-LBW. Compared to term-AGA-NBW, the highest mortality risk was for preterm-LBW phenotypes (HR=36.2(95%CI 35.6-36.8) preterm-AGA-LBW, HR=62.0(95%CI 60.8-63.2) preterm-SGA-LBW). The increased mortality risk associated with vulnerable newborn phenotypes was highest in the first month of life, with attenuated but continued high risk in the post-neonatal period and 1-4 years of age.

INTERPRETATION

Our findings support the value of using more detailed phenotypes to identify those at highest risk. More granular data can inform care at the individual level, advance research, especially for prevention, and accelerate progress towards global targets such as the Sustainable Development Goals.

FUNDING

Wellcome Trust.

Hubungan Pemberian Asi Eksklusif Dan Status Gizi Ibu Dengan Pertumbuhan Lingkar Kepala Bayi Usia 6 Bulan

Background: Measurement of head circumference is highly crucial during the early years of life which considered as an anthropometric parameter substantially correlated with brain size. The emergence of head circumference aberration functions to warn of abnormal brain development. Breast milk is the ideal nutritional provider that babies need for optimal healthy growth. Nursing mothers with good nutrition will affect their nutritional status. The nutritional status will determine the quantity and quality of dairy products that indirectly play a role in determining children’s nutritional status.Objective: Analyzing the relationship between exclusive breastfeeding and maternal nutritional status with the growth of the head circumference of 6 months old infants.Method: Using a cross-sectional design in the Kaliwates, Jember. Subjects were 6 months old infants in which 128 babies were selected by purposive sampling. Data on maternal nutritional status were based on Body Mass Index (BMI). Data on exclusive breastfeeding were based on interviews and KMS data. The baby’s head circumference data were based on direct measurements and those were interpreted using WHO growth charts. Then, the data were analyzed using Chi-Square test.Results: The results showed that there was a significant relationship between exclusive breastfeeding (p<0.001) and maternal nutritional status (p=0.028) with the growth of the baby’s head circumference.Conclusion: Exclusive breastfeeding and maternal nutritional status are associated with the growth of the baby’s head circumference. ABSTRAKLatar Belakang : Pengukuran lingkar kepala sangat penting selama tahun awal kehidupan, hal ini merupakan parameter antropometri yang sangat berkorelasi dengan ukuran otak. Terjadi penyimpangan pada lingkar kepala, maka memperingatkan perkembangan otak yang tidak normal. Air susu ibu merupakan penyedia nutrisi ideal yang dibutuhkan bayi untuk pertumbuhan yang sehat secara optimal. Ibu menyusui dengan pemenuhan gizi yang baik akan mempengaruhi status gizinya. Status gizi tersebut akan menentukan kuantitas dan kualitas produk susu yang secara tidak langsung berperan dalam menentukan status gizi anak.Tujuan : Menganalisis hubungan pemberian ASI eksklusif dan status gizi ibu dengan pertumbuhan lingkar kepala bayi usia 6 bulan.Metode : Menggunakan desain cross-sectional di wilayah Kecamatan Kaliwates, Kabupaten Jember. Subjek penelitian adalah bayi usia 6 bulan, 128 bayi dipilih dengan purposive sampling. Data status gizi ibu berdasarkan IMT. Data pemberian ASI eksklusif berdasarkan wawancara dan data KMS. Data lingkar kepala bayi berdasarkan pengukuran langsung dan diinterprestasikan menggunakan grafik pertumbuhan WHO. Analisis data menggunakan uji Chi-Square.Hasil : Hasil penelitian menunjukkan bahwa ada hubungan yang bermakna antara pemberian ASI eksklusif (ρ = <0,001 dan OR 9,58) dan status gizi ibu (ρ = 0,028 dan OR 0,28) dengan pertumbuhan lingkar kepala bayi usia 6 bulan.Kesimpulan : Pemberian ASI eksklusif pada bayi akan memberikan pertumbuhan lingkar kepala yang normal dibandingkan bayi yang tidak diberikan ASI eksklusif dan pada ibu yang memiliki status gizi baik juga akan memberikan pertumbuhan lingkar kepala bayi yang normal dibandingkan dengan ibu berstatus gizi kurang dan gemuk. Kata kunci : status gizi, ASI eksklusif, lingkar kepala

Intelligence in youth and health behaviours in middle age

OBJECTIVE

We investigated the association between intelligence in youth and a range of health-related behaviours in middle age.

METHOD

Participants were the 5347 men and women who responded to the National Longitudinal Survey of Youth 1979 (NLSY-79) 2012 survey. IQ was recorded with the Armed Forces Qualification Test (AFQT) when participants were aged 15 to 23 years of age. Self-reports on exercise (moderate activity, vigorous activity, and strength training), dietary, smoking, drinking, and oral health behaviours were recorded when participants were in middle age (mean age = 51.7 years). A series of regression analyses tested for an association between IQ in youth and the different health related behaviours in middle age, while adjusting for childhood socio-economic status (SES) and adult SES.

RESULTS

Higher IQ in youth was significantly associated with the following behaviours that are beneficial to health: being more likely to be able to do moderate cardiovascular activity (Odds Ratio, 95% CI) (1.72, 1.35 to 2.20, p < .001) and strength training (1.61, 1.37 to 1.90, p < .001); being less likely to have had a sugary drink in the previous week (0.75, 0.71 to 0.80, p < .001); a lower likelihood of drinking alcohol heavily (0.67, 0.61 to 0.74, p < .001); being less likely to smoke (0.60, 0.56 to 0.65, p < .001); being more likely to floss (1.47, 1.35 to 1.59, p < .001); and being more likely to say they "often" read the nutritional information (1.20, 1.09 to 1.31, p < .001) and ingredients (1.24, 1.12 to 1.36, p < .001) on food packaging compared to always reading them. Higher IQ was also linked with dietary behaviours that may or may not be linked with poorer health outcomes (i.e. being more likely to have skipped a meal (1.10, 1.03 to 1.17, p = .005) and snacked between meals (1.37, 1.26 to 1.50, p < .001) in the previous week). An inverted u-shaped association was also found between IQ and the number of meals skipped per week. Higher IQ was also linked with behaviours that are known to be linked with poorer health (i.e. a higher likelihood of drinking alcohol compared to being abstinent from drinking alcohol (1.58, 1.47 to 1.69, p < .001)). A u-shaped association was found between IQ and the amount of alcohol consumed per week and an inverted u-shaped association was found between IQ and the number of cigarettes smoked a day. Across all outcomes, adjusting for childhood SES tended to attenuate the estimated effect size only slightly. Adjusting for adult SES led to more marked attenuation but statistical significance was maintained in most cases.

CONCLUSION

In the present study, a higher IQ in adolescence was associated with a number of healthier behaviours in middle age. In contrast to these results, a few associations were also identified between higher intelligence and behaviours that may or may not be linked with poor health (i.e. skipping meals and snacking between meals) and with behaviours that are known to be linked with poor health (i.e. drinking alcohol and the number of cigarettes smoked). To explore mechanisms of association, future studies could test for a range of health behaviours as potential mediators between IQ and morbidity or mortality in later life.

International variation in programmes for assessment of children's neurodevelopment in the community: Understanding disparate approaches to evaluation of motor, social, emotional, behavioural and cognitive function

BACKGROUND

Few areas of medicine demonstrate such international divergence as child development screening and surveillance. Many countries have nationally mandated surveillance policies, but the content of programmes and mechanisms for delivery vary enormously. The cost of programmes is substantial but no economic evaluations have been carried out. We have critically examined the history, underlying philosophy, content and delivery of programmes for child development assessment in five countries with comprehensive publicly funded health services (Denmark, Finland, Norway, Scotland and Sweden). The specific focus of this article is on motor, social, emotional, behavioural and global cognitive functioning including language.

FINDINGS

Variations in developmental surveillance programmes are substantially explained by historical factors and gradual evolution although Scotland has undergone radical changes in approach. No elements of universal developmental assessment programmes meet World Health Organization screening criteria, although some assessments are configured as screening activities. The roles of doctors and nurses vary greatly by country as do the timing, content and likely costs of programmes. Inter-professional communication presents challenges to all the studied health services. No programme has evidence for improved health outcomes or cost effectiveness.

CONCLUSIONS

Developmental surveillance programmes vary greatly and their structure appears to be driven by historical factors as much as by evidence. Consensus should be reached about which surveillance activities constitute screening, and the predictive validity of these components needs to be established and judged against World Health Organization screening criteria. Costs and consequences of specific programmes should be assessed, and the issue of inter-professional communication about children at remediable developmental risk should be prioritised.

The Intellectual Disability Mortality Disadvantage: Diminishing With Age?

On average, adults with intellectual disability (ID) have higher mortality risk than their peers in the general population. However, the effect of age on this mortality disadvantage has received minimal attention. Using data from the 1986-2011 National Health Interview Survey-Linked Mortality Files (NHIS-LMF), discrete time hazard models were used to compare mortality risk for adults with and without ID by age and gender. Increased mortality risk was present for all adults with ID, but was most pronounced among younger age females. The mortality differential between those with and without ID diminished with increased age for both females and males. Findings support the argument that heterogeneity of frailty may explain differences in mortality risk between those with and without ID.

Does n-3 LCPUFA supplementation during pregnancy increase the IQ of children at school age? Follow-up of a randomised controlled trial

INTRODUCTION

Despite recommendations that pregnant women increase their docosahexaenoic acid (DHA) intake to support fetal brain development, a recent systematic review found a lack of high-quality data to support the long-term effects of DHA supplementation on children's neurodevelopment.

METHODS AND ANALYSIS

We will assess child neurodevelopment at 7 years of age in follow-up of a multicentre double-blind randomised controlled trial of DHA supplementation in pregnancy. In 2010-2012, n=2399 Australian women with a singleton pregnancy <21 weeks' gestation were randomised to receive 3 capsules daily containing a total dose of 800 mg DHA/day or a vegetable oil placebo until birth. N=726 children from Adelaide (all n=97 born preterm, random sample of n=630 born at term) were selected for neurodevelopmental follow-up and n=638 (preterm n=85) are still enrolled at 7 years of age. At the 7-year follow-up, a psychologist will assess the primary outcome, IQ, with the Wechsler Abbreviated Scale of Intelligence, Second Edition. Specific measures of executive functioning (Fruit Stroop and the Rey Complex Figure), attention (Test of Everyday Attention for Children), memory and learning (Rey Auditory Verbal Learning Test), language (Clinical Evaluation of Language Fundamentals, Fourth Edition) and basic educational skills (Wide Range Achievement Test, Fourth Edition) will also be administered. Caregivers will be asked to complete questionnaires measuring behaviour and executive functioning. Families, clinicians and research personnel are blinded to group assignment with the exception of families who requested unblinding prior to the follow-up. All analyses will be conducted according to the intention-to-treat principal.

ETHICS AND DISSEMINATION

All procedures will be approved by the relevant institutional ethics committees prior to start of the study. The results of this study will be disseminated in peer-reviewed journal publications and academic presentations.

TRIAL REGISTRATION NUMBERS

ACTRN12605000569606 and ACTRN12614000770662.

Parenting Practices at 24 to 47 Months and IQ at Age 8: Effect-Measure Modification by Infant Temperament

Cognitive development might be influenced by parenting practices and child temperament. We examined whether the associations between parental warmth, control and intelligence quotient (IQ) may be heightened among children in difficult temperament. Participants were from the Avon Longitudinal Study of Parents and Children (n = 7,044). Temperament at 6 months was measured using the Revised Infant Temperament Questionnaire and classified into 'easy' and 'difficult'. Parental warmth and control was measured at 24 to 47 months and both were classified into 2 groups using latent class analyses. IQ was measured at 8 years using the Wechsler Intelligence Scale for Children and dichotomized (<85 and ≥85) for analyzing effect-measure modification by temperament. Linear regression adjusted for multiple confounders and temperament showed lower parental warmth was weakly associated with lower IQ score [β = -0.52 (95% CI 1.26, 0.21)], and higher parental control was associated with lower IQ score [β = -2.21 (-2.95, -1.48)]. Stratification by temperament showed no increased risk of having low IQ in temperamentally difficult children [risk ratio (RR) = 0.97 95% CI 0.65, 1.45)] but an increased risk among temperamentally easy children (RR = 1.12 95% CI 0.95, 1.32) when parental warmth was low. There was also no increased risk of having low IQ in temperamentally difficult children (RR = 1.02 95% CI 0.69, 1.53) but there was an increased risk among temperamentally easy children (RR = 1.30 95% CI 1.11, 1.53) when parental control was high. For both parental warmth and control, there was some evidence of negative effect-measure modification by temperament on the risk-difference scale and the risk-ratio scale. It may be more appropriate to provide parenting interventions as a universal program rather than targeting children with difficult temperament.

Association of Cognitive Function With Cause-Specific Mortality in Middle and Older Age: Follow-up of Participants in the English Longitudinal Study of Ageing

We examined the little-tested associations between general cognitive function in middle and older age and later risk of death from chronic diseases. In the English Longitudinal Study of Ageing (2002-2012), 11,391 study participants who were 50-100 years of age at study induction underwent a battery of cognitive tests and provided a range of collateral data. In an analytical sample of 9,204 people (4,982 women), there were 1,488 deaths during follow-up (mean duration, 9.0 years). When we combined scores from 4 cognition tests that represented 3 acknowledged key domains of cognitive functioning (memory, executive function, and processing speed), cognition was inversely associated with deaths from cancer (per each 1-standard-deviation decrease in general cognitive function score, hazard ratio = 1.21, 95% CI: 1.10, 1.33), cardiovascular disease (hazard ratio = 1.71, 95% CI: 1.55, 1.89), other causes (hazard ratio = 2.07, 95% CI: 1.79, 2.40), and respiratory illness (hazard ratio = 2.48, 95% CI: 2.12, 2.90). Controlling for a range of covariates, such as health behaviors and socioeconomic status, and left-censoring to explore reverse causality had very little impact on the strength of these relationships. These findings indicate that cognitive test scores can provide relatively simple indicators of the risk of death from an array of chronic diseases and that these associations appear to be independent of other commonly assessed risk factors.

Intelligence in youth and health at age 50

Background

The link between intelligence in youth and all-cause mortality in later-life is well established. To better understand this relationship, the current study examines the links between pre-morbid intelligence and a number of specific health outcomes at age 50 using the NLSY-1979 cohort.

Methods

Participants were the 5793 participants in the NLSY-79 who responded to questions about health outcomes at age 50. Sixteen health outcomes were examined: two were summary measures (physical health and functional limitation), 9 were diagnosed illness conditions, 4 were self-reported conditions, and one was a measure of general health status. Linear and logistic regressions were used, as appropriate, to examine the relationship between intelligence in youth and the health outcomes. Age, sex and both childhood and adult SES, and its sub-components – income, education, & occupational prestige – are all adjusted for separately.

Results & conclusion

Higher pre-morbid intelligence is linked with better physical health at age 50, and a lower risk for a number of chronic health conditions. For example, a 1 SD higher score in IQ was significantly associated with increased odds of having good, very good, or excellent health, with an odds ratio of 1.70 (C.I. 1.55–1.86). Thirteen of the illness outcomes were significantly and negatively associated with IQ in youth; the odds ratios ranged from 0.85 for diabetes/high blood sugar to 0.65 for stroke, per one standard deviation higher score in IQ. Adjustment for childhood SES led to little attenuation but adult SES partially mediated the relationship for a number of conditions. Mediation by adult SES was not consistently explained by any one of its components—income, education, and occupation status. The current findings contribute to our understanding of lower intelligence as a risk factor for poor health and how this may contribute to health inequalities.

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We examined links between intelligence in youth and health at age 50 in NLSY-1979.

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Higher intelligence in youth is linked with better physical health at age 50.

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Higher intelligence in youth is linked with lower risk for chronic illnesses.

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Adult but not childhood SES partially mediated the intelligence–health relationship.

Childhood Club Participation and All-Cause Mortality in Adulthood: A 65-Year Follow-Up Study of a Population-Representative Sample in Scotland

OBJECTIVES

Social participation in middle and older age is associated with lower mortality risk across many prospective cohort studies. However, there is a paucity of evidence on social participation in youth in relation to mortality, which could help inform an understanding of the origin of the association and give credence to causality. The present study investigates the relation of early-life club membership-a proxy measure of social participation-with mortality risk in older age in a nationally representative sample.

METHODS

We linked historical data collected on the 6-Day Sample of the Scottish Mental Survey 1947 during the period 1947 to 1963 with vital status records up to April 2014. Analyses were based on 1059 traced participants (446 deceased).

RESULTS

Club membership at age 18 years was associated with lower mortality risk by age 78 years (hazard ratio = 0.54, 95% confidence interval = 0.44-0.68, p < .001). Club membership remained a significant predictor in models that included early-life health, socioeconomic status, measured intelligence, and teachers' ratings of dependability in personality.

CONCLUSIONS

In a study that circumvented the problem of reverse causality, a proxy indicator of social participation in youth was related to lower mortality risk. The association may be mediated by several behavioral and neurobiological factors, which prospective aging cohort studies could address.

Parental academic involvement in adolescence as predictor of mental health trajectories over the life course: a prospective population-based cohort study

BACKGROUND

Mental health problems are rising, especially among younger people, indicating a need to identify determinants of the development of mental health over the life course. Parental involvement in their children's studies, particularly in terms of academic socialisation, has been shown to predict better mental health in adulthood, as well as other more favourable health outcomes, but no study published so far has examined its impact on trajectories of mental health. We therefore sought to elucidate the role of parental involvement at age 16 on the life course development of internalised mental health symptoms.

METHODS

In a population-based cohort (452 women and 488 men, 87% of the eligible participants), we examined the association between parental involvement in their offspring's studies, measured by teacher and pupil ratings at age 16, and an index of internalised mental health symptoms at the ages of 16, 18, 21, 30, and 43. Using latent class trajectory analysis, 5 different trajectories were derived from these indices: Very low stable (least symptoms), Low stable, Increasing, Moderate stable, and High decreasing (most symptoms). Multinomial logistic regression was used to regress trajectory membership on the parental involvement variables.

RESULTS

Teacher-rated parental interest in their offspring's studies during the last year of compulsory school was associated with a lower risk of entering the Moderate stable (OR = 0.54; 95% CI 0.30 to 0.98) and High decreasing (OR = 0.41; 0.18 to 0.91) trajectories, compared with the Low stable, also after adjustment for sex, parental social class and mental health, family unemployment and own school grades. Both these associations were present only in children with grades above the national average. Student-rated availability of assistance with homework was associated with a higher chance of entering the Very low stable trajectory in the whole sample (OR = 1.24; 1.07 to 1.43), in men (OR = 1.25; 1.05 to 1.48) and in those with above average grades (OR = 1.39; 1.13 to 1.72), and with a lower risk of entering the Moderate stable in women (OR = 0.74; 0.55 to 0.99), also after the same adjustments.

CONCLUSIONS

Parental involvement in their offspring's studies may buffer against poor mental health in adolescence which may track into adulthood.

Association Between Low IQ Scores and Early Mortality in Men and Women: Evidence From a Population-Based Cohort Study

Lower (versus higher) IQ scores have been shown to increase the risk of early mortality, however, the underlying mechanisms are poorly understood and previous studies underrepresent individuals with intellectual disability (ID) and women. This study followed one third of all senior-year students (approximately aged 17) attending public high school in Wisconsin, U.S. in 1957 (n  =  10,317) until 2011. Men and women with the lowest IQ test scores (i.e., IQ scores ≤ 85) had increased rates of mortality compared to people with the highest IQ test scores, particularly for cardiovascular disease. Importantly, when educational attainment was held constant, people with lower IQ test scores did not have higher mortality by age 70 than people with higher IQ test scores. Individuals with lower IQ test scores likely experience multiple disadvantages throughout life that contribute to increased risk of early mortality.

Does high intelligence improve prognosis? The association of intelligence with recurrence and mortality among Swedish men with coronary heart disease

BACKGROUND

Lower intelligence early in life is associated with increased risks for coronary heart disease (CHD) and mortality. Intelligence level might affect compliance to treatment but its prognostic importance in patients with CHD is unknown.

METHODS

A cohort of 1923 Swedish men with a measure of intelligence from mandatory military conscription in 1969-1970 at age 18-20, who were diagnosed with CHD 1991-2007, were followed to the end of 2008.

PRIMARY OUTCOME

recurrent CHD event. Secondary outcome: case fatality from the first event, cardiovascular and all-cause mortality. National registers provided information on CHD events, comorbidity, mortality and socioeconomic factors.

RESULTS

The fully adjusted HRs for recurrent CHD for medium and low intelligence, compared with high intelligence, were 0.98, (95% CIs 0.83 to 1.16) and 1.09 (0.89 to 1.34), respectively. The risks were increased for cardiovascular and all-cause mortality with lower intelligence, but were attenuated in the fully adjusted models (fully adjusted HRs for cardiovascular mortality 1.92 (0.94 to 3.94) and 1.98 (0.89 to 4.37), respectively; for all-cause mortality 1.63 (1.00 to 2.65) and 1.62 (0.94 to 2.78), respectively). There was no increased risk for case-fatality at the first event (fully adjusted ORs 1.06 (0.73 to 1.55) and 0.97 (0.62 to 1.50), respectively).

CONCLUSIONS

Although we found lower intelligence to be associated with increased mortality in middle-aged men with CHD, there was no evidence for its possible effect on recurrence in CHD.

Negative events in childhood predict trajectories of internalizing symptoms up to young adulthood: an 18-year longitudinal study

BACKGROUND

Common negative events can precipitate the onset of internalizing symptoms. We studied whether their occurrence in childhood is associated with mental health trajectories over the course of development.

METHODS

Using data from the TEMPO study, a French community-based cohort study of youths, we studied the association between negative events in 1991 (when participants were aged 4-16 years) and internalizing symptoms, assessed by the ASEBA family of instruments in 1991, 1999, and 2009 (n = 1503). Participants' trajectories of internalizing symptoms were estimated with semi-parametric regression methods (PROC TRAJ). Data were analyzed using multinomial regression models controlled for participants' sex, age, parental family status, socio-economic position, and parental history of depression.

RESULTS

Negative childhood events were associated with an increased likelihood of concurrent internalizing symptoms which sometimes persisted into adulthood (multivariate ORs associated with > = 3 negative events respectively: high and decreasing internalizing symptoms: 5.54, 95% CI: 3.20-9.58; persistently high internalizing symptoms: 8.94, 95% CI: 2.82-28.31). Specific negative events most strongly associated with youths' persistent internalizing symptoms included: school difficulties (multivariate OR: 5.31, 95% CI: 2.24-12.59), parental stress (multivariate OR: 4.69, 95% CI: 2.02-10.87), serious illness/health problems (multivariate OR: 4.13, 95% CI: 1.76-9.70), and social isolation (multivariate OR: 2.24, 95% CI: 1.00-5.08).

CONCLUSIONS

Common negative events can contribute to the onset of children's lasting psychological difficulties.

Reaction time and mortality from the major causes of death: the NHANES-III study

OBJECTIVE

Studies examining the relation of information processing speed, as measured by reaction time, with mortality are scarce. We explored these associations in a representative sample of the US population.

METHODS

Participants were 5,134 adults (2,342 men) aged 20-59 years from the Third National Health and Nutrition Examination Survey (NHANES III, 1988-94).

RESULTS

Adjusted for age, sex, and ethnic minority status, a 1 SD slower reaction time was associated with a raised risk of mortality from all-causes (HR = 1.25, 95% CI 1.12, 1.39) and cardiovascular disease (CVD) (HR = 1.36, 95% CI 1.17, 1.58). Having 1 SD more variable reaction time was also associated with greater risk of all-cause (HR = 1.36, 95% CI 1.19, 1.55) and CVD (HR = 1.50, 95% CI 1.33, 1.70) mortality. No associations were observed for cancer mortality. The magnitude of the relationships was comparable in size to established risk factors in this dataset, such as smoking.

INTERPRETATION

Alongside better-established risk factors, reaction time is associated with increased risk of premature death and cardiovascular disease. It is a candidate risk factor for all-cause and cause-specific mortality.

The prospective association between childhood cognitive ability and somatic symptoms and syndromes in adulthood: the 1958 British birth cohort

BACKGROUND

Cognitive ability is negatively associated with functional somatic symptoms (FSS) in childhood. Lower childhood cognitive ability might also predict FSS and functional somatic syndromes in adulthood. However, it is unknown whether this association would be modified by subjective and objective measures of parental academic expectations.

METHODS

14 068 participants from the 1958 British birth cohort, whose cognitive ability was assessed at 11 years. Outcomes were somatic symptoms at 23, 33 and 42 years. Self-reported irritable bowel syndrome (IBS), chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) and operationally defined CFS-like illness were measured at 42 years.

RESULTS

Lower cognitive ability at age 11 years was associated with somatic symptoms at ages 23, 33 and 42 years. Adjusting for sex, childhood internalising problems, previous somatic symptoms and concurrent psychological symptoms, childhood cognitive ability remained negatively associated with somatic symptoms at age 23 years (β=-0.060, 95% CI -0.081 to -0.039, p<0.01), 33 years (β = -0.031, 95% CI -0.050 to -0.011, p<0.01), but not with somatic symptoms at 42 years. Overall, we found no clear association between lower childhood cognitive ability and CFS/ME, CFS-like illness and IBS. Associations between cognitive ability and somatic symptoms at 23 years were moderated by low parental social class, but not by subjective indicators of parental academic expectations.

CONCLUSIONS

Lower childhood cognitive ability predicted somatic symptoms, but not CFS/ME, CFS-like illness and IBS in adulthood. While earlier research indicated an important role for high parental academic expectations in the development of early-life FSS, these expectations do not seem relevant for somatic symptoms or functional somatic syndromes in later adulthood.

Cognitive ability changes and dynamics of cortical thickness development in healthy children and adolescents

Intelligence quotient (IQ) scores tend to remain stable across the lifespan. Nevertheless, in some healthy individuals, significant decreases or increases in IQ have been observed over time. It is unclear whether such changes reflect true functional change or merely measurement error. Here, we applied surface-based corticometry to investigate vertex-wise cortical surface area and thickness correlates of changes in Full Scale IQ (FSIQ), Performance IQ (PIQ) and Verbal IQ (VIQ) in a representative sample of children and adolescents (n=188, mean age=11.59years) assessed two years apart as part of the NIH Study of Normal Brain Development. No significant associations between changes in IQ measures and changes in cortical surface area were observed, whereas changes in FSIQ, PIQ, and VIQ were related to rates of cortical thinning, mainly in left frontal areas. Participants who showed reliable gains in FSIQ showed no significant changes in cortical thickness on average, whereas those who exhibited no significant FSIQ change showed moderate declines in cortical thickness. Importantly, individuals who showed large decreases in FSIQ displayed the steepest and most significant reductions in cortical thickness. Results support the view that there can be meaningful cognitive ability changes that impact IQ within relatively short developmental periods and show that such changes are associated with the dynamics of cortical thickness development.

Retinal vessel caliber and lifelong neuropsychological functioning: retinal imaging as an investigative tool for cognitive epidemiology

Why do more intelligent people live healthier and longer lives? One possibility is that intelligence tests assess health of the brain, but psychological science has lacked technology to evaluate this hypothesis. Digital retinal imaging, a new, noninvasive method to visualize microcirculation in the eye, may reflect vascular conditions in the brain. We studied the association between retinal vessel caliber and neuropsychological functioning in the representative Dunedin birth cohort. Wider venular caliber was associated with poorer neuropsychological functioning at midlife, independently of potentially confounding factors. This association was not limited to any specific test domain and extended to informants' reports of cohort members' cognitive difficulties in everyday life. Moreover, wider venular caliber was associated with lower childhood IQ tested 25 years earlier. The findings indicate that retinal venular caliber may be an indicator of neuropsychological health years before the onset of dementing diseases and suggest that digital retinal imaging may be a useful investigative tool for psychological science.

Childhood determinants of adult psychiatric disorder

The aim of this project was to assess the current evidence from longitudinal studies for childhood determinants of adult mental illness. Because of the variable and often prolonged period between factors in childhood and the identification of mental illness in adults, prospective studies, particularly birth cohorts, offer the best chance of demonstrating associations in individuals.

A review was undertaken in 2006 of the published literature from longitudinal studies, together with some large-scale retrospective studies and relevant reviews which provided supplementary evidence. The main focus was upon potentially ameliorable characteristics, experiences or situations of childhood; however, other factors, not determinants but pre-cursors, associated with later mental illness could not be left out.

Seven major electronic data-bases of published research were interrogated with a range of key-words and the results supplemented from personal searches, enquiries and reference trails. In excess of 1,500 abstracts were read to select 250 papers for full review. The material was assessed in relation to ten factors:

Psychological disturbance; Genetic Influences; Neurological Deviance; Neuroticism; Behaviour; School Performance; Adversity; Child Abuse or Neglect; Parenting and parent-child relationships; Disrupted and Disfunctional Families.

In 2011 the search was repeated for the period 2006 to mid-2011, using the same search terms and supplemented in the same manner. Over 1,800 abstracts emerged and almost 200 papers selected for more detailed review. These were then integrated into the original text with modifications where necessary. The whole text was then revised and edited in January / February 2012.

There is continuing evidence for the association with later mental ill-health for each of these ten factors, but with different degrees of conviction. The evidence for each is discussed in detail and weighed both separately and in relation to others. These are then summarised, and the research implications are considered. Finally, the implications for prevention are discussed together with the practical potential for preventive and health-promoting programmes.

A prospective study of positive early-life psychosocial factors and favorable cardiovascular risk in adulthood

BACKGROUND

The American Heart Association's national goals for cardiovascular health promotion emphasize that cardiovascular risk originates early in life, but little is known about childhood factors that may increase the likelihood of having a favorable cardiovascular risk (FCR) in adulthood. We examined the prospective association between positive childhood factors and the likelihood of midlife FCR. We also considered pathways through which childhood factors may influence FCR.

METHODS AND RESULTS

We studied 415 adults (mean age=42.2 years) of the Collaborative Perinatal Project, a national cohort initiated in 1959 to 1966. We examined 3 positive childhood factors assessed at age 7 years: attention regulation (ability to stay focused), cognitive ability, and positive home environment. Of these adults, 10.6% had FCR in midlife. Adjusting for demographics and childhood cardiovascular health, a 1-unit increase in childhood attention regulation, cognitive ability, and positive home environment was associated with 2.4 (95% confidence interval, 1.1-4.7), 1.8 (95% confidence interval, 1.1-2.9), and 1.3 (95% confidence interval, 1.1-1.6) higher respective odds of having midlife FCR. The association with childhood attention regulation was maintained when accounting for adulthood factors; education and diet in part explained the associations with childhood cognitive ability and home environment. The effect of each attribute was additive as those with high levels of each childhood factor had 4.3 higher odds (95% confidence interval, 1.01-18.2) of midlife FCR in comparison with those low in all factors.

CONCLUSIONS

Positive childhood psychosocial factors may promote healthy adult cardiovascular functioning. Primordial prevention efforts aimed at preventing the development of cardiovascular risk should consider building on childhood psychosocial resources.

Cognitive ability in early adulthood is associated with later suicide and suicide attempt: the role of risk factors over the life course

BACKGROUND

Cognitive ability/intelligence quotient (IQ) in youth has previously been associated with subsequent completed and attempted suicide, but little is known about the mechanisms underlying the associations. This study aims to assess the roles of various risk factors over the life course in explaining the observed relationships.

METHOD

The present investigation is a cohort study based on data on IQ test performance and covariates, recorded on 49 321 Swedish men conscripted in 1969-1970, at ages 18-20 years. Information on suicides and hospital admissions for suicide attempt up to the age of 57 years, childhood and adult socio-economic position, and adult family formation, was obtained from linkage to national registers.

RESULTS

Lower IQ was associated with increased risks of both suicide and suicide attempt during the 36 years of follow-up. The associations followed a dose-response pattern. They were attenuated by approximately 45% in models controlling for social background, mental ill-health, aspects of personality and behavior, adult socio-economic position and family formation. Based on one-unit decreases in IQ test performance on a nine-point scale, the hazard ratios between ages 35 and 57 years were: for suicide 1.19 [95% confidence interval (CI) 1.13-1.25], fully adjusted 1.10 (95% CI 1.04-1.18); and for suicide attempt 1.25 (95% CI 1.20-1.31), fully adjusted 1.14 (95% CI 1.09-1.20).

CONCLUSIONS

Cognitive ability was found to be associated with subsequent completed and attempted suicide. The associations were attenuated by 45% after controlling for risk factors measured over the life course. Psychiatric diagnosis, maladjustment and aspects of personality in young adulthood, and social circumstances in later adulthood, contributed in attenuating the associations.

Head circumference of infants born to mothers with different educational levels; the Generation R Study

OBJECTIVE

Head circumference (HC) reflect growth and development of the brain in early childhood. It is unknown whether socioeconomic differences in HC are present in early childhood. Therefore, we investigated the association between socioeconomic position (SEP) and HC in early childhood, and potential underlying factors.

METHODS

The study focused on Dutch children born between April 2002 and January 2006 who participated in The Generation R Study, a population-based prospective cohort study in Rotterdam, The Netherlands. Maternal educational level was used as indicator of SEP. HC measures were concentrated around 1, 3, 6 and 11 months. Associations and explanatory factors were investigated using linear regression analysis, adjusted for potential mediators.

RESULTS

The study included 3383 children. At 1, 3 and 6 months of age, children of mothers with a low education had a smaller HC than those with a high education (difference at 1 month: -0.42 SD; 95% CI: -0.54,-0.30; at 3 months: -0.27 SD; 95% CI -0.40,-0.15; and at 6 months: -0.13 SD; 95% CI -0.24,-0.02). Child's length and weight could only partially explain the smaller HC at 1 and 3 months of age. At 6 months, birth weight, gestational age and parental height explained the HC differences. At 11 months, no HC differences were found.

CONCLUSION

Educational inequalities in HC in the first 6 months of life can be mainly explained by pregnancy-related factors, such as birth weight and gestational age. These findings further support public health policies to prevent negative birth outcomes in lower socioeconomic groups.

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.

Consequences of age-related cognitive declines

Adult age differences in a variety of cognitive abilities are well documented, and many of those abilities have been found to be related to success in the workplace and in everyday life. However, increased age is seldom associated with lower levels of real-world functioning, and the reasons for this lab-life discrepancy are not well understood. This article briefly reviews research concerned with relations of age to cognition, relations of cognition to successful functioning outside the laboratory, and relations of age to measures of work performance and achievement. The final section discusses several possible explanations for why there are often little or no consequences of age-related cognitive declines in everyday functioning.

Sibling analysis of adolescent intelligence and chronic diseases in older adulthood

PURPOSE

We examined whether associations of adolescent intelligence with chronic diseases in adulthood are explained by socioeconomic factors, health behaviors, or common sources of variance in intelligence and chronic disease risk.

METHODS

A prospective cohort study (Wisconsin Longitudinal Study) of high school graduates and their siblings with intelligence assessed in adolescence and chronic diseases reported in adulthood (n = 10,168; mean age 53.9 and n = 9051; mean age 64.8 in two follow-ups).

RESULTS

After adjustment for age and sex, greater intelligence was associated with lower risk of heart disease (odds ratio per 1 SD advantage in intelligence 0.93; 95% confidence interval 0.87-0.99), circulation problems (0.85; 0.79-0.92), stroke (0.80; 0.70-0.91), and diabetes (0.88; 0.81-0.95). Participants' risk of stroke and circulation problems also was predicted by their sibling's intelligence, suggesting potential common causes for intelligence and cerebrovascular diseases. Sibling analysis provided no support for shared family environment in explaining associations between intelligence and disease outcomes because between-families and within-siblings regression models were not different. Adjusting for common risk factors had little impact on these associations. In contrast, adjusting for adult socioeconomic status attenuated the associations by 25%-100% (66% on average).

CONCLUSIONS

Multiple mechanisms may link intelligence with occurrence of chronic diseases of major public health importance.

Birthweight and mortality in adulthood: a systematic review and meta-analysis

BACKGROUND

Small birth size may be associated with increased risk of cardiovascular diseases (CVD), whereas large birth size may predict increased risk of obesity and some cancers. The net effect of birth size on long-term mortality has only been assessed in individual studies, with conflicting results.

METHODS

The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer. The studies were systematically reviewed and those reporting hazard ratios (HRs) and 95% confidence intervals (95% CIs) per kilogram (kg) increase in birthweight were included in generic inverse variance meta-analyses.

RESULTS

For all-cause mortality, 36,834 deaths were included and the results showed a 6% lower risk (adjusted HR = 0.94, 95% CI: 0.92-0.97) per kg higher birthweight for men and women combined. For cardiovascular mortality, the corresponding inverse association was stronger (HR = 0.88, 95% CI: 0.85-0.91). For cancer mortality, HR per kg higher birthweight was 1.13 (95% CI: 1.07-1.19) for men and 1.04 (95% CI: 0.98-1.10) for women (P(interaction) = 0.03). Residual confounding could not be eliminated, but is unlikely to account for the main findings.

CONCLUSION

These results show an inverse but moderate association of birthweight with adult mortality from all-causes and a stronger inverse association with cardiovascular mortality. For men, higher birthweight was strongly associated with increased risk of cancer deaths. The findings suggest that birthweight can be a useful indicator of processes that influence long-term health.

Intelligence in youth and all-cause-mortality: systematic review with meta-analysis

BACKGROUND

A number of prospective cohort studies have examined the association between intelligence in childhood or youth and life expectancy in adulthood; however, the effect size of this association is yet to be quantified and previous reviews require updating.

METHODS

The systematic review included an electronic search of EMBASE, MEDLINE and PSYCHINFO databases. This yielded 16 unrelated studies that met inclusion criteria, comprising 22,453 deaths among 1,107,022 participants. Heterogeneity was assessed, and fixed effects models were applied to the aggregate data. Publication bias was evaluated, and sensitivity analyses were conducted.

RESULTS

A 1-standard deviation (SD) advantage in cognitive test scores was associated with a 24% (95% confidence interval 23-25) lower risk of death, during a 17- to 69-year follow-up. There was little evidence of publication bias (Egger's intercept = 0.10, P = 0.81), and the intelligence-mortality association was similar for men and women. Adjustment for childhood socio-economic status (SES) in the nine studies containing these data had almost no impact on this relationship, suggesting that this is not a confounder of the intelligence-mortality association. Controlling for adult SES in five studies and for education in six studies attenuated the intelligence-mortality hazard ratios by 34 and 54%, respectively.

CONCLUSIONS

Future investigations should address the extent to which attenuation of the intelligence-mortality link by adult SES indicators is due to mediation, over-adjustment and/or confounding. The explanation(s) for association between higher early-life intelligence and lower risk of adult mortality require further elucidation.

Direct and indirect pathways connecting cognitive ability with cardiovascular disease risk: socioeconomic status and multiple health behaviors

OBJECTIVE

To model and test direct and indirect pathways connecting general cognitive ability (g) with cardiovascular disease risk factors, via socioeconomic status (SES) and multiple health behaviors.

METHODS

A sample comprising participants in the Health and Lifestyle Survey, a prospective cohort study of a representative sample of U.K. adults in 1984/5 (n = 4939, 2426 males).

RESULTS

Two mediating latent variables were proposed that connected a latent cognitive trait (named g) with a latent trait of cardiovascular disease (CVD) risk: multiple health behaviors (defined by smoking, physical inactivity, and weekly saturated fat intake) and SES (defined by educational attainment, occupational social class, and income). In males and females, SES mediated the association between g and CVD risk, but the mediation was moderated by years of age. A direct effect from g to CVD risk was also significant, but this was restricted to older males. Multiple health behaviors offered no explanatory power, because they were not influenced by g.

CONCLUSIONS

SES may connect g with CVD risk in males, but not systematically across the life course. Moderated mediation is a novel way to illustrate that direct and indirect pathways can vary as a function of age. Explanations that emphasize g or SES are not mutually exclusive; there are direct and indirect contributions to CVD risk from each source, and these vary across the life course.

The association of cognitive performance with mental health and physical functioning strengthens with age: the Whitehall II cohort study

BACKGROUND

Cognitive performance has been associated with mental and physical health, but it is unknown whether the strength of these associations changes with ageing and with age-related social transitions, such as retirement. We examined whether cognitive performance predicted mental and physical health from midlife to early old age.

METHOD

Participants were 5414 men and 2278 women from the Whitehall II cohort study followed for 15 years between 1991 and 2006. The age range included over the follow-up was from 40 to 75 years. Mental health and physical functioning were measured six times using SF-36 subscales. Cognitive performance was assessed three times using five cognitive tests assessing verbal and numerical reasoning, verbal memory, and phonemic and semantic fluency. Socio-economic status (SES) and retirement were included as covariates.

RESULTS

High cognitive performance was associated with better mental health and physical functioning. Mental health differences associated with cognitive performance widened with age from 39 to 76 years of age, whereas physical functioning differences widened only between 39 and 60 years and not after 60 years of age. SES explained part of the widening differences in mental health and physical functioning before age 60. Cognitive performance was more strongly associated with mental health in retired than non-retired participants, which contributed to the widening differences after 60 years of age.

CONCLUSIONS

The strength of cognitive performance in predicting mental and physical health may increase from midlife to early old age, and these changes may be related to SES and age-related transitions, such as retirement.

Honeybee associative learning performance and metabolic stress resilience are positively associated

BACKGROUND

Social-environmental influences can affect animal cognition and health. Also, human socio-economic status is a covariate factor connecting psychometric test-performance (a measure of cognitive ability), educational achievement, lifetime health, and survival. The complimentary hypothesis, that mechanisms in physiology can explain some covariance between the same traits, is disputed. Possible mechanisms involve metabolic biology affecting integrity and stability of physiological systems during development and ageing. Knowledge of these relationships is incomplete, and underlying processes are challenging to reveal in people. Model animals, however, can provide insights into connections between metabolic biology and physiological stability that may aid efforts to reduce human health and longevity disparities.

RESULTS

We document a positive correlation between a measure of associative learning performance and the metabolic stress resilience of honeybees. This relationship is independent of social factors, and may provide basic insights into how central nervous system (CNS) function and metabolic biology can be associated. Controlling for social environment, age, and learning motivation in each bee, we establish that learning in Pavlovian conditioning to an odour is positively correlated with individual survival time in hyperoxia. Hyperoxia induces oxidative metabolic damage, and provides a measure of metabolic stress resistance that is often related to overall lifespan in laboratory animals. The positive relationship between Pavlovian learning ability and stress resilience in the bee is not equally established in other model organisms so far, and contrasts with a genetic cost of improved associative learning found in Drosophila melanogaster.

CONCLUSIONS

Similarities in the performances of different animals need not reflect common functional principles. A correlation of honeybee Pavlovian learning and metabolic stress resilience, thereby, is not evidence of a shared biology that will give insight about systems integrity in people. Yet, the means to resolve difficult research questions often come from findings in distant areas of science while the model systems that turn out to be valuable are sometimes the least predictable. Our results add to recent findings indicating that honeybees can become instrumental to understanding how metabolic biology influences life outcomes.