Anja Taanila

5-HTTLPR genotype and anxiety-related personality traits: a meta-analysis and new data.

We investigated the strength of evidence for association of the 5‐HTTLPR polymorphism and the personality trait of Harm Avoidance. We used new primary data from a large sample of adults drawn from the Finnish population. We also applied meta‐analytic techniques to synthesize existing published data. The large number of studies of the 5‐HTTLPR polymorphism allowed us to apply a formal test of publication bias, as well as formally investigate the impact of potential moderating factors such as measurement instrument. Univariate ANOVA of primary data (n = 3,872), with 5‐HTTLPR genotype as a between‐groups factor, indicated no evidence of association with Harm Avoidance (P = 0.99). Meta‐analysis indicated no evidence of significant association of 5‐HTTLPR with Harm Avoidance (d = 0.02, P = 0.37), or EPQ Neuroticism (d = 0.01, P = 0.71), although there was evidence of association with NEO Neuroticism (d = 0.18, P < 0.001). Our analyses indicate that the 5‐HTTLPR variant is not associated with Harm Avoidance. Together with our previous analyses of a large sample of participants with extreme Neuroticism scores (defined by the EPQ), we have data that excludes a meaningful genetic effect of the 5‐HTTLPR on two measures of anxiety‐related personality traits. There remains the possibility that the variant influences the NEO personality questionnaire measure of Neuroticism. However, a large, well‐powered primary study is required to test this hypothesis directly and adequately.

Maternal adiposity prior to pregnancy is associated with ADHD symptoms in offspring: evidence from three prospective pregnancy cohorts

Objectives:We examine whether pregnancy weight (pre-pregnancy body mass index (BMI) and/or weight gain) is related to core symptoms of attention deficit hyperactivity disorder (ADHD) in school-age offspring.Design:Follow-up of prospective pregnancy cohorts from Sweden, Denmark and Finland within the Nordic Network on ADHD.Methods:Maternal pregnancy and delivery data were collected prospectively. Teachers rated inattention and hyperactivity symptoms in offspring. High scores were defined as at least one core symptom rated as ‘severe’ and two as ‘present’ (approximately 10% of children scored in this range). Logistic regression and latent class analyses were used to examine maternal pregnancy weight in relation to childrens ADHD core symptoms.Results:Teacher rated 12 556 school-aged children. Gestational weight gain outside of the Institute of Medicine guidelines was not related to ADHD symptoms (below recommendations: odds ratio (OR): 0.96; 95% confidence interval (CI): 0.81, 1.14; above recommendations: OR: 0.98; 95% CI: 0.82, 1.16). To examine various patterns of pre-pregnancy BMI and weight gain, we used latent class analysis and found significant associations between classes that included pre-pregnancy overweight or obesity and a high ADHD symptom score in offspring, ORs ranged between 1.37 (95% CI: 1.07, 1.75) and 1.89 (95% CI: 1.13, 3.15) adjusted for gestational age, birth weight, weight gain, pregnancy smoking, maternal age, maternal education, child gender, family structure and cohort country of origin. Children of women who were both overweight and gained a large amount of weight during gestation had a 2-fold risk of ADHD symptoms (OR: 2.10, 95% CI: 1.19, 3.72) compared to normal-weight women.Conclusions:We show for the first time that pre-pregnancy BMI is associated with ADHD symptoms in children. Our results are of public health significance if the associations are causal and will then add ADHD symptoms in offspring to the list of deleterious outcomes related to overweight and obesity in the prenatal period.

Maternal Smoking and Hyperactivity in 8-Year-Old Children

OBJECTIVE To investigate the association between maternal smoking during pregnancy and hyperactivity in 8-year-old children. METHOD The study population consisted of children from the Northern Finland 1985/86 Birth Cohort. At 8-year follow-up 9,357 children were alive. Mothers provided information both during pregnancy and at age 8. Teachers assessed childrens behavior by the Childrens Behavior Questionnaire (Rutter B2). Unadjusted analyses and stratification were used to study associations and confounding variables. A multivariate logistic regression model was fitted to assess the independent association between smoking and outcome. RESULTS Maternal smoking was associated with hyperactivity even after adjustment for sex, family structure, socioeconomic status, maternal age, and maternal alcohol use (odds ratio 1.30; 1.08-1.58). The association was particularly notable among children of young mothers with low social standing. A positive dose-response relationship was seen between maternal smoking and hyperactivity. CONCLUSION This study, the largest population-based prospective follow-up on fetal nicotine exposure and later behavioral disorders, confirms earlier descriptions of the link between maternal smoking during gestation and childhood hyperactivity. Discontinuation or decreased use of cigarettes during pregnancy might improve behavioral outcome of children.

Is maternal smoking during pregnancy a risk factor for Hyperkinetic disorder?—findings from a sibling design

BACKGROUND Studies have consistently shown that pregnancy smoking is associated with twice the risk of hyperactivity/inattention problems in the offspring. An association of this magnitude may indicate behavioural difficulties as one of the most important health effects related to smoking during pregnancy. However, social and genetic confounders may fully or partially account for these findings. METHODS A cohort including all singletons born in Finland from 1 January 1987 through 31 December 2001 was followed until 1 January 2006 based on linkage of national registers. Data were available for 97% (N = 868,449) of the population. We followed singleton children of smoking and non-smoking mothers until they had an International Classification of Diseases, 10th revision, diagnosis of hyperkinetic disorder (HKD) or to the end of the observation period. We used sibling-matched Cox regression analyses to control for social and genetic confounding. RESULTS We found a much smaller association between exposure to maternal smoking during pregnancy and risk of HKD in children using the sibling-matched analysis [hazards ratio (HR) = 1.20, 95% confidence interval (CI) 0.97-1.49] than was observed in the entire cohort (HR 2.01, 95% CI 1.90-2.12). CONCLUSIONS Our findings suggest that the strong association found in previous studies may be due to time-stable familial factors, such as environmental and genetic factors. If smoking is a causal factor, the effect is small and less important than what the previous studies indicate.

Do inattention and hyperactivity symptoms equal scholastic impairment? evidence from three European cohorts

BackgroundAttention Deficit/Hyperactivity Disorder (ADHD) affects many children, adolescents, and adults and is associated with a number of impairments. Poor academic performance is related to ADHD in clinical samples. However, it is unclear to what extent core ADHD symptoms and scholastic impairment are related in non-referred school-aged children.MethodsData come from three population-based cohorts from Sweden, Denmark, and Finland, which are part of the Nordic Network on ADHD. The combined sample size was 13,087 children who were studied at ages 7–8 or 10–12 years. Teachers rated children on inattention and hyperactivity symptoms and reported childrens scholastic performance on basic skills.ResultsThere was a significant association in all cohorts between core ADHD symptoms and scholastic impairment in reading, writing, and mathematics. Particularly, inattention was related to a two to tenfold increase in scholastic impairment. Prevalence of hyperactivity symptoms was similar across the three cohorts, but inattention was lowest among children from the Finnish cohort, after stratification on living conditions.ConclusionThese results extend previous reports of scholastic impairment among children with clinically diagnosed ADHD to non-referred population samples from three European countries. Surveillance policies should be implemented in school systems to catch children in need of behavioral or scholastic support early.

Physical activity and obesity mediate the association between childhood motor function and adolescents’ academic achievement

The global epidemic of obesity and physical inactivity may have detrimental implications for young people’s cognitive function and academic achievement. This prospective study investigated whether childhood motor function predicts later academic achievement via physical activity, fitness, and obesity. The study sample included 8,061 children from the Northern Finland Birth Cohort 1986, which contains data about parent-reported motor function at age 8 y and self-reported physical activity, predicted cardiorespiratory fitness (cycle ergometer test), obesity (body weight and height), and academic achievement (grades) at age 16 y. Structural equation models with unstandardized (B) and standardized (β) coefficients were used to test whether, and to what extent, physical activity, cardiorespiratory fitness, and obesity at age 16 mediated the association between childhood motor function and adolescents’ academic achievement. Physical activity was associated with a higher grade-point average, and obesity was associated with a lower grade-point average in adolescence. Furthermore, compromised motor function in childhood had a negative indirect effect on adolescents’ academic achievement via physical inactivity (B = –0.023, 95% confidence interval = –0.031, –0.015) and obesity (B = –0.025, 95% confidence interval = –0.039, –0.011), but not via cardiorespiratory fitness. These results suggest that physical activity and obesity may mediate the association between childhood motor function and adolescents’ academic achievement. Compromised motor function in childhood may represent an important factor driving the effects of obesity and physical inactivity on academic underachievement.

Maintenance of genetic variation in human personality: Testing evolutionary models by estimating heritability due to common causal variants and investigating the effect of distant inbreeding

Personality traits are basic dimensions of behavioral variation, and twin, family, and adoption studies show that around 30% of the between‐individual variation is due to genetic variation. There is rapidly growing interest in understanding the evolutionary basis of this genetic variation. Several evolutionary mechanisms could explain how genetic variation is maintained in traits, and each of these makes predictions in terms of the relative contribution of rare and common genetic variants to personality variation, the magnitude of nonadditive genetic influences, and whether personality is affected by inbreeding. Using genome‐wide single nucleotide polymorphism (SNP) data from > 8000 individuals, we estimated that little variation in the Cloninger personality dimensions (7.2% on average) is due to the combined effect of common, additive genetic variants across the genome, suggesting that most heritable variation in personality is due to rare variant effects and/or a combination of dominance and epistasis. Furthermore, higher levels of inbreeding were associated with less socially desirable personality trait levels in three of the four personality dimensions. These findings are consistent with genetic variation in personality traits having been maintained by mutation–selection balance.

Infant developmental milestones: a 31-year follow-up

This study examined the association between infant developmental milestones and educational level at 31 years of age in the Northern Finland 1966 Birth Cohort (n = 12 058). Developmental data (age at standing, walking, speaking, and measures of bowel and bladder control) were gathered from childrens welfare centres. Information on type of schooling at 14 years of age was reported by children and parents. School achievement at 16 years of age and educational level at 31 years were obtained from national registers. Those who reached infant developmental milestones sooner in their first year of life had significantly better (p < 0.05) mean scores in teacher ratings at 16 years, and at 31 years they were more likely to have achieved a better educational level than slower developers. The adjusted odds ratios for individuals who developed more slowly to remain at a basic educational level (7 to 16y) ranged significantly from 1.1 to 1.3. The possibility of advancing from secondary to tertiary level was 1.4 times greater in faster developers than in slow developers. In conclusion, those who develop faster during their first year of life tend to attain higher levels of education in adolescence and adulthood.

MAINTENANCE OF GENETIC VARIATION IN HUMAN PERSONALITY: TESTING EVOLUTIONARY MODELS BY ESTIMATING HERITABILITY DUE TO COMMON CAUSAL VARIANTS AND INVESTIGATING THE EFFECT OF DISTANT INBREEDING

Personality traits are basic dimensions of behavioral variation, and twin, family, and adoption studies show that around 30% of the between‐individual variation is due to genetic variation. There is rapidly growing interest in understanding the evolutionary basis of this genetic variation. Several evolutionary mechanisms could explain how genetic variation is maintained in traits, and each of these makes predictions in terms of the relative contribution of rare and common genetic variants to personality variation, the magnitude of nonadditive genetic influences, and whether personality is affected by inbreeding. Using genome‐wide single nucleotide polymorphism (SNP) data from > 8000 individuals, we estimated that little variation in the Cloninger personality dimensions (7.2% on average) is due to the combined effect of common, additive genetic variants across the genome, suggesting that most heritable variation in personality is due to rare variant effects and/or a combination of dominance and epistasis. Furthermore, higher levels of inbreeding were associated with less socially desirable personality trait levels in three of the four personality dimensions. These findings are consistent with genetic variation in personality traits having been maintained by mutation–selection balance.

THE LONG-TERM EFFECTS OF CHILDREN'S EARLY-ONSET DISABILITY ON MARITAL RELATIONSHIPS

To investigate the long‐term effects of a childs chronic illness or severe physical or intellectual disability on parents and their marital relationship, the parents of 89 children, aged 14–17, years were interviewed. The parents returned a questionnaire and a social worker interviewed them. One‐fifth of the respondents had experienced the childs disability as contributing positively to the marital relationship, 25% reported impairment in some areas of the marital relatonship, while only 7% felt that they had drawn apart from each other. A higher level of occupational education, insecurity at onset, heavy daily demands for care of the child, unequal distribution of tasks between the spouses and a lack of time for leisure activities were found to be risk factors for impaired marital satisfaction. Adequate information, a realistic notion of the illness or disability and practical advice for everyday life seemed to be the protective factors for the marital relationship.