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

Paternal intelligence affects school grades in children with and without ADHD - a register-based study

ADHD profoundly impacts educational attainment, quality of life, and health in young adults. However, certain subgroups of ADHD patients seem to do quite well, potentially due to differences in intelligence and socioeconomic status. Here we used paternal intelligence from the Swedish Defence Conscription and Assessment register, to investigate the role of genetic propensity for intelligence, on school performance in a large cohort of ADHD patients and matched controls. Patients treated for ADHD in Linköping, Sweden between 1995 and 2020 (n = 3262), sex- and age-matched controls (n = 9591) as well as their parents and siblings were identified using regional and national registers. Socioeconomic and demographic data, ADHD diagnosis and treatment and school grades at age 16 for the study population were extracted from Swedish National registers. We explored the associations between paternal intelligence and child school performance using linear mixed models and mediation analyses, taking a wide range of potential covariates into account. Results indicate that paternal intelligence was positively associated with standardized school grades in their offspring (Zadjusted=0.09, 95%CI 0.07, 0.10). This effect was present in both ADHD patients and controls, but ADHD patients had significantly lower standardized grades (Zadjusted=-1.03, 95%CI -1.08, -0.98). Child ADHD did not serve as a mediator for how paternal intelligence affected school grades. Our findings indicate that ADHD prevents children from reaching their academic potential at all levels of paternal intelligence. Increased understanding of the contributions of ADHD, intelligence, and SES to functional outcomes can help clinicians to better personalize interventions to the unique preconditions in each patient.

Brain structural parameters correlate with University Selection Test outcomes in Chilean high school graduates

How well students learn and perform in academic contexts is a focus of interest for the students, their families, and the entire educational system. Although evidence has shown that several neurobiological factors are involved in scholastic achievement (SA), specific brain measures associated with academic outcomes and whether such associations are independent of other factors remain unclear. This study attempts to identify the relationship between brain structural parameters, and the Chilean national University Selection Test (PSU) results in high school graduates within a multidimensional approach that considers socio-economic, intellectual, nutritional, and demographic variables. To this end, the brain morphology of a sample of 102 students who took the PSU test was estimated using Magnetic Resonance Imaging. Anthropometric parameters, intellectual ability (IA), and socioeconomic status (SES) were also measured. The results revealed that, independently of sex, IA, gray matter volume, right inferior frontal gyrus thickness, and SES were significantly associated with SA. These findings highlight the role of nutrition, health, and socioeconomic variables in academic success.

Stature and education among Roma women: taller stature is associated with better educational and economic outcomes

The association between body height and educational outcome, as measured by years of completed schooling, was investigated among Roma women in Serbia in 2014-2018. Height, demographic data, level of schooling and reproductive histories were collected from 691 Roma women aged between 16 and 80 years living in rural settlements in central and western Serbia. Multinomial logistic regression analysis showed that short stature was associated with an increased risk of low education, possibly as a result of poor growth and developmental disadvantage in early life. Roma cultural practices were also shown to influence the school achievement of these Roma girls: in addition to height, education was positively associated with a higher bride price and better socioeconomic status, as acquired through marriage. For Roma women, height might influence not only their level of education but also their lifetime prospects.

A multifactorial approach of nutritional, intellectual, brain development, cardiovascular risk, socio-economic, demographic and educational variables affecting the scholastic achievement in Chilean students: An eight- year follow-up study

The aim of this study was to quantitate the relative impact of nutritional, intellectual, brain development, cardiovascular risk, socio-economic, demographic and educational variables on the results of the 2009 Quality Education Measurement System (SIMCE) tests of language and mathematics for scholastic achievement (SA) applying a multifactorial approach, in school-age children of the 2010 5th elementary school grade (5ESG) and of the 1st grade of high school (1HSG). The purposes were: i) to test the hypothesis that intellectual ability, the level of SA of the educational establishments in the 2009 SIMCE tests, sex, parental schooling levels, and head circumference-for-age Z-score are the most relevant parameters associated with 2009 SIMCE outcomes; ii) to determine the predictive ability of the 2009 SIMCE results in determining the 2013 SIMCE outcomes for the 2010 5ESG cohort (when they graduated from elementary school, 8th grade) and for determining the 2013 University Selection Test (PSU) outcomes for the 2010 1HSG group (for university admission, when they graduated from high school, 4th grade); iii) to determine the association between the 2009 SIMCE results with the 2017 PSU outcomes for the 2010 5ESG group (for university admission, when they graduated from high school, 4th grade). A representative, proportional and stratified sample of 33 schools of the Metropolitan Region of Chile was randomly chosen. In these schools, 1,353 school-age children of both sexes, of the 2010 5ESG (n = 682; mean age = 10.8 years, SD = 0.6) and of the 2010 1HSG (n = 671; mean age = 14.8 years, SD = 0.6) participated. In both grades and tests, the findings confirm the hypotheses formulated. 2009 SIMCE outcomes were positively and significantly associated with 2013 SIMCE and with 2017 PSU and, with 2013 PSU outcomes in school-age children from 2010 5ESG and 1HSG, respectively. These findings may be useful for educational and health planning in Chile and countries in a comparable stage of development.

Maternal and offspring intelligence in relation to BMI across childhood and adolescence

Objective

The present study tested the association between both mothers’ and offspring’s intelligence and offspring’s body mass index (BMI) in youth.

Method

Participants were members of the National Longitudinal Survey of Youth 1979 (NLSY-79) Children and Young Adults cohort (n = 11,512) and their biological mothers who were members of the NLSY-79 (n = 4932). Offspring’s IQ was measured with the Peabody Individual Achievement Test (PIAT). Mothers’ IQ was measured with the Armed Forces Qualification Test (AFQT). A series of regression analyses tested the association between IQ and offspring’s BMI by age group, while adjusting for pre-pregnancy BMI and family SES. The analyses were stratified by sex and ethnicity (non-Black and non-Hispanic, Black, and Hispanic).

Results

The following associations were observed in the fully adjusted analyses. For the non-Blacks and non-Hispanics, a SD increment in mothers’ IQ was negatively associated with daughters’ BMI across all age-groups, ranging from β = −0.12 (95% CI −0.22 to −0.02, p = 0.021) in late childhood, to β = −0.17 (95% C.I. −0.27 to −0.07, p = 0001), in early adolescence and a SD increment in boys’ IQ was positively associated with their BMI in early adolescence β = 0.09 (95% CI 0.01–0.18, p = 0.031). For Blacks, there was a non-linear relationship between mothers’ IQ and daughters’ BMI across childhood and between girls’ IQ and BMI across adolescence. There was a positive association between mothers’ IQ and sons’ BMI in early adolescence (β = 0.17, 95% CI 0.02–0.32, p = 0.030). For Hispanic boys, there was a positive IQ-BMI association in late childhood (β = 0.19, 95% CI 0.05–0.33, p = 0.008) and early adolescence (β = 0.17, 95% CI 0.04–0.31, p = 0.014).

Conclusion

Mothers’ IQ and offspring’s IQ were associated with offspring’s BMI. The relationships varied in direction and strength across ethnicity, age group and sex. Obesity interventions may benefit from acknowledging the heterogeneous influence that intelligence has on childhood BMI.

Fathers' intelligence measured at age 18-20 years is associated with offspring smoking: linking the Swedish 1969 conscription cohort to the Swedish Survey of Living Conditions

Background

An association between lower IQ of parents, measured early in life, and smoking among their offspring has been reported. The extent to which other background factors account for this association is unknown.

Methods

Data on IQ, smoking, mental health, social class, parental divorce and social problems in a cohort of men born during 1949–1951 and conscripted for military service in 1969 were linked to smoking data on 682 offspring interviewed in the Swedish Surveys of Living Conditions 1984–2009.

Results

In an age-adjusted model, a one-step decrease on a stanine scale was associated with an OR of 1.19 (95% CI 1.04 to 1.35) for offspring smoking. Adjusting for father's socioeconomic background and smoking, mental illness and social problems in youth only marginally lowered the OR's.

Conclusions

Lower IQ among fathers measured at ages 18–20 years was associated with smoking in their offspring. The association was not explained by father's social class in childhood or a higher prevalence of mental illness, social problems or smoking measured among the fathers in their late adolescence.

Intelligence and obesity: which way does the causal direction go?

PURPOSE OF REVIEW

The negative association between intelligence and obesity has been well established, but the direction of causality is unclear. The present review surveys the recent studies on the topic with both cross-sectional and longitudinal data in an attempt to establish causality.

RECENT FINDINGS

Most studies in the area employ cross-sectional data and conclude (without empirical justification) that obesity causes intellectual impairment. The few studies that employ prospectively longitudinal data, however, uniformly conclude that lower intelligence leads to BMI gains and obesity. A close examination of three such studies, from three different nations (Sweden, New Zealand, and the UK), leaves little doubt that the causality runs from low intelligence to obesity.

SUMMARY

The conclusion in previous studies that obesity impairs cognitive function stems from improper interpretation of a negative association between intelligence and obesity from cross-sectional studies. Results from the analyses of high-quality, population-based, prospectively longitudinal data firmly establish that low intelligence increases the chances of obesity.

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.

Neuropsychological assessment at school-age and prenatal low-level exposure to mercury through fish consumption in an Italian birth cohort living near a contaminated site

The relative effects of prenatal and postnatal low-level mercury exposure and fish intake on child neurodevelopment are still controversial. Limited evidence is available from Mediterranean populations. In this prospective study, we measured the Verbal and Performance IQ in Italian children at school-age who were resident in an area declared as a National contaminated site because of mercury pollution, taking into account the possible beneficial effect of fish consumption and potential confounders. A mother-child cohort made up of 242 children was established at birth in Northeastern Italy in 2001. Their mothers were interviewed approximately 2 months after delivery to determine type, quantity, and origin of fish consumed during pregnancy and about a number of mother, child and family characteristics. Total mercury (THg) and methyl mercury (MeHg) were assessed in maternal hair and breast milk and in the child's hair. When children reached 7-9 years of age, 154 (63.6%) parents gave consent to participate in a follow-up evaluation. On that occasion, a child's hair sample was collected to determine the current concentration of THg, mothers were asked to complete a self-administered questionnaire, and children underwent neuropsychological testing. Verbal IQ, performance IQ and full scale IQ were measured by the Wechsler Intelligence Scale for Children (WISC III) administered by psychologists at school or local health centers. Demographic, socioeconomic and lifestyle information, medical information of the child's family and the child's dietary habits were collected using a questionnaire filled in by mothers. Multivariable linear regression models were used to evaluate the association between prenatal THg exposure through fish consumption of mothers in pregnancy and children's IQ after adjustment for possible confounders such as fish consumption of mothers in pregnancy, child's fish consumption at follow-up, child's birthweight, maternal cigarette smoking during pregnancy, house size and property place of residence during pregnancy and gender. THg in the child's hair at 7 years of age was fairly correlated with THg in maternal hair at delivery (rs=0.35; p<0.0001) and was strongly correlated with child's seafood consumption (rs=0.50, p<0.0001). No differences in maternal THg levels were found when comparing children with low or extremely low or high or extremely high scores vs others, considering separately full scale, verbal, and performance IQs. Children born from mothers with hair THg levels greater than or equal to 2000ng/g had full scale, verbal and performance IQs which were 4-5 points lower than children born from women with lower THg levels, but these differences were not statistically significant. Fresh fish intake of mothers in pregnancy was slightly positively associated with full scale and performance but not so with verbal IQs. Canned fish showed to be negatively associated with all the outcome variables. Unexpectedly, children born to mothers from one town showed IQ scores significantly lower than the other children; however, none of the many variables considered in these analyses could explain this result. The relatively low Hg levels found in the biological samples did not provide evidence of high and extensive Hg exposure in this population. Although THg levels in maternal and child's biological samples are correlated with fish consumption, the effects of THg and fish on neurological outcomes go in opposite directions. These results do not allow to develop recommendations regarding fish consumption in pregnancy but suggest that keeping THg hair levels<2000ng/g might be desirable.