Effect of birth weight, maternal education and prenatal smoking on offspring intelligence at school age.

To examine the combined effect of birth weight, mothers' education and prenatal smoking on psychometrically measured intelligence at school age 1,822 children born in 1992-1999 and attending the first six grades from 45 schools representing all of the fifteen Estonian counties with information on birth weight, gestational age and mother's age, marital status, education, parity and smoking in pregnancy, and intelligence tests were studied. The scores of Raven's Standard Progressive Matrices were related to the birth weight: in the normal range of birth weight (>or=2500 g) every 500 g increase in birth weight was accompanied by around 0.7-point increase in IQ scores. A strong association between birth weight and IQ remained even if gestational age and mother's age, marital status, education, place of residence, parity and smoking during pregnancy have been taken into account. Maternal prenatal smoking was accompanied by a 3.3-point deficit in children's intellectual abilities. Marriage and mother's education had an independent positive correlation with offspring intelligence. We concluded that the statistical effect of birth weight, maternal education and smoking in pregnancy on offspring's IQ scores was remarkable and remained even if other factors have been taken into account.

Associations of self-esteem and temperament traits to self- and teacher-reported social status among classmates.

The present study examined the validity of self- and teacher-reported social status and its relations to self-esteem and temperament in a geographically representative cohort of Finnish adolescents (N = 3941, mean age 15.1 years). High agreement was found between self- and teacher-rated social status (r = 0.42). Different aspects of self-esteem were differently related to social status. When other temperament and self-esteem variables were included in the analyses, strongest predictor for self-rated social status in both genders was social self-esteem (p < 0.01) and for teacher-rated social status general self-esteem (p < 0.01). The strongest temperamental predictors of social status were lower inhibition in girls (p < 0.01, self- and teacher-rated) and higher impulsivity (p < 0.01, self-rated) and activity (p < 0.01, teacher-rated) in boys. The present findings are consistent with the view that social functioning and peer relations are associated with individual differences in self-concept and temperament dimensions.

Global self-esteem across the life span: a cross-sectional comparison between representative and self-selected internet samples.

The cross-sectional trajectory of global self-esteem across the life span was examined administering the Rosenberg and Single-Item Self-Esteem scales to Estonians (N = 29,463) who were either randomly selected from the National Census to represent the population or self-recruited through the Internet. The results (a) challenge the recent conclusion of a universal age trajectory of self-esteem, (b) demonstrate that self-recruited Internet data collection method is biased compared to random sampling, and (c) present that different self-esteem items have dissimilar trajectories. A variance component analysis confirmed that age differences in self-esteem are relatively small compared to interindividual differences and measurement error.

Association of traffic behavior with personality and platelet monoamine oxidase activity in schoolchildren.

PURPOSE: Estimations, attitudes and behavioral decisions in everyday life, including traffic-related situations, are influenced by personality traits. It is known that that there is a strong link between certain personality traits, particularly impulsivity, and central serotonergic functioning. This study examined associations between traffic behavior, personality and platelet monoamine oxidase activity, a marker of central nervous system serotonergic neurotransmission, in schoolchildren. METHODS: Participants were 483 schoolchildren (aged 15.3 +/- .5 years) who filled in questionnaires on traffic behavior and personality. Platelet monoamine oxidase activity was measured radioenzymatically. RESULTS: Simple logistic regression analysis revealed that subjects with riskier traffic behavior had higher impulsivity (both adaptive as maladaptive facets) as well as lower Openness, Agreeableness, and Conscientiousness. In multiple logistic regression analysis, many of these associations became nonsignificant, but the high traffic risk group was more likely to have lower Agreeableness and lower platelet MAO activity. Low platelet MAO activity was a significant predictor of risky traffic behavior only in girls who were also influenced by higher Excitement Seeking. Smoking was an independent predictor of all groups with high traffic risks. CONCLUSION: Risky traffic behavior in schoolchildren is associated with basic personality dimensions, most consistently with Agreeableness, and with different aspects of impulsivity. Some of these traits, particularly in girls, may be related to central serotonergic neuronal activity.

The growth of IQ among Estonian schoolchildren from ages 7 to 19.

The Standard Progressive Matrices test was standardized in Estonia on a representative sample of 4874 schoolchildren aged from 7 to 19 years. When the IQ of Estonian children was expressed in relation to British and Icelandic norms, both demonstrated a similar sigmoid relationship. The youngest Estonian group scored higher than the British and Icelandic norms: after first grade, the score fell below 100 and remained lower until age 12, and after that age it increased above the mean level of these two comparison countries. The difference between the junior school children and the secondary school children may be due to schooling, sampling error or different trajectories of intellectual maturation in different populations. Systematic differences in the growth pattern suggest that the development of intellectual capacities proceeds at different rates and the maturation process can take longer in some populations than in others.

A new estimate of the IQ in Estonia.

The Standard Progressive Matrices was standardized in Estonia in 2001 on a sample of 1,835 7- to 11-yr.-olds. The mean IQ of the Estonian sample was estimated at 98 in relation to a British IQ of 100 and 99 based on the combined results for two studies.

A study of intelligence in Estonia.

The Standard Progressive Matrices was standardised in Estonia in 2001 on a sample of 2,689 12- to 18-yr.-olds. The mean IQ of the Estonian sample was approximately 5 points higher than British IQ norms of 1979. Adjustment for the estimated secular increase of intelligence in Britain reduces the mean IQ of the Estonian sample to 100.2, in relation to a British mean of 100. A particular interest of the result from Estonia is that the intelligence of a European population is apparently not impaired by decades of low living standards.