Growth trajectories and intellectual abilities in young adulthood: The Helsinki Birth Cohort study.

Slow childhood growth is associated with poorer intellectual ability. The critical periods of growth remain uncertain. Among 2,786 Finnish male military conscripts (1952-1972) born in 1934-1944, the authors tested how specific growth periods from birth to age 20 years predicted verbal, visuospatial, and arithmetic abilities at age 20. Small head circumference at birth predicted poorer verbal, visuospatial, and arithmetic abilities. The latter 2 measures were also associated with lower weight and body mass index (weight (kg)/height (m)(2)) at birth (for a 1-standard-deviation (SD) decrease in test score per SD decrease in body size > or = 0.05, P's < 0.04). Slow linear growth and weight gain between birth and age 6 months, between ages 6 months and 2 years, or both predicted poorer performance on all 3 tests (for a 1-SD decrease in test score per SD decrease in growth > or = 0.05, P's < 0.03). Reduced linear growth between ages 2 and 7 years predicted worse verbal ability, and between age 11 years and conscription it predicted worse performance on all 3 tests. Prenatal brain growth and linear growth up to 2 years after birth form a first critical period for intellectual development. There is a second critical period, specific for verbal development, between ages 2 and 7 years and a third critical period for all 3 tested outcomes during adolescence.

Premorbid intellectual functioning in bipolar disorder and schizophrenia: results from a cohort study of male conscripts.

OBJECTIVE: Premorbid intellectual impairment has been described in schizophrenia, but little is known about premorbid intellectual functioning in bipolar disorder or other psychoses. In this study, premorbid intellectual ability was investigated in individuals with bipolar disorder, schizophrenia, or other psychoses. METHOD: Results on verbal, arithmetic, and visuospatial reasoning tests were obtained for 195,019 apparently healthy male subjects conscripted into the Finnish Defense Forces during 1982-1987 (mean age, 19.9 years). Linkage with the Finnish Hospital Discharge Register (mean follow-up time, 7.1 years) identified conscripts later diagnosed with bipolar disorder (N=100), schizophrenia (N=621), or other psychoses (N=527). RESULTS: Poor performance on the visuospatial reasoning test at age 20 was associated with higher risks for all three disorders. The odds ratios indicating the difference in risk of illness between the lowest and highest of nine performance categories were 34.65 (95% confidence interval [CI], 4.05-296.44) for bipolar disorder, 13.76 (95% CI=5.49-34.47) for schizophrenia, and 4.28 (95% CI=2.09-8.77) for other psychoses. In contrast, the higher the score for arithmetic reasoning, the greater the risk of bipolar disorder; a high score was associated with a more than 12-fold greater risk. Verbal test performance was not associated with higher risk for psychiatric disorder. CONCLUSIONS: These results indicate that premorbid visuospatial reasoning is impaired in bipolar disorder and schizophrenia and, to a smaller extent, in other psychoses. This suggests that a subtle neurodevelopmental aberration is involved in the etiology of bipolar disorder and schizophrenia. High arithmetic test performance may be associated with greater risk for bipolar disorder.

Premorbid personality factors in schizophrenia and bipolar disorder: results from a large cohort study of male conscripts.

The present study explored the premorbid personality traits Neuroticism, Extraversion, and Disinhibition in individuals later diagnosed with psychotic disorders. Results on personality questionnaires and intellectual performance tests were obtained for 213,443 apparently healthy male subjects (mean age: 20.1 years) conscripted into the Finnish Defence Forces during the period 1982-1987. Linkage with the Finnish Hospital Discharge Register (mean follow-up time: 14.1 years, SD = 1.7) identified conscripts later diagnosed with schizophrenia (N = 1,328), bipolar disorder (N = 98), or other psychoses (N = 456). Both before and after controlling for intellectual performance, high Neuroticism predicted future onset of schizophrenia and other psychoses, and high Extraversion predicted future onset of bipolar disorder. The data of the present research showed for the 1st time that premorbid personality traits predict heightened risk for psychotic disorders beyond intellectual performance and also showed for the 1st time an association between premorbid Extraversion and bipolar disorder.

Intellectual ability in early adulthood and type 2 diabetes in later life.

The aim of this study is to assess whether intellectual ability in young adult men predicts the development of type 2 diabetes in later life. 641 men participating in the Helsinki Birth Cohort Study were administered a 2-h (75 g) oral glucose tolerance test at a mean age of 61 years. Intellectual ability was assessed during compulsory military service at a mean age of 20 years. Associations were explored using linear and logistic regression models. Intellectual ability in young adulthood did not predict glucose tolerance at age 61 years. However, educational attainment was associated with the prevalence of type 2 diabetes, independently of early intellectual ability. Men with the highest educational attainment were less likely to have type 2 diabetes than men with the lowest educational attainment (OR = 0.50, 95% CI 0.28-0.91). While education seems to protect from type 2 diabetes, we could not detect a connection between early intellectual ability and impairment in glucose regulation in later adulthood.

Workplace drug testing in a military organization: results and experiences from the testing program in the Finnish Defence Forces.

In the military environment drug abuse is a particular risk for occupational safety. In the Finnish Defence Forces a drug testing program was conducted in 2002-2005; soldiers, professional civilians, and military students were tested when applying for a work or right to study; furthermore, annually 5% of the personnel were subjected to random testing. In total, over 2000 urine samples were analyzed in an accredited laboratory for cannabis, opiates, amphetamines, or cocaine. In this article, the drug testing program as a part of the anti-drug strategy of the Finnish Defence Forces is described, and the findings including practical experiences and financial expenses are reported. Only one person applying for a civilian post tested positive for amphetamine and cannabis. In seven other samples codeine and morphine were detected; these were, however, due to prescribed medication, not drug abuse. In the execution of the program, no particular difficulties were reported. In conclusion, it seems that the use of illicit drugs in the Finnish military is extremely rare, at least partly due to the successful anti-drug strategy. After an elaborate planning, even an extensive drug testing program can be executed without substantial setbacks. In the future, the effectiveness of drug testing programs as a means of improving occupational safety needs to be investigated in controlled studies using comparative design.