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Thursday, October 30, 2008

Genetic and environmental contributions to the diversity of substances used in adolescent twins: a longitudinal study of age and sex effects
Volume 103 Issue 10, Pages 1744 - 1751

To determine how genetic and environmental contributions affecting the number of psychoactive substances used varies with age and gender over the course of adolescence

The average diversity of substances used increased over time for both males and females, and males generally reported a wider diversity of substances used than females. Influences of genetic factors increased with age and were greater for males than for females at ages 14 and 17 years. Genetic factors remained consistent (i.e. highly correlated) across ages for both males and females, as did shared environmental influences for males. Non-shared environmental factors for both sexes and females' shared environmental factors were age-specific.

Regardless of sex, the proportion of variance in substances used attributable to genetic factors increases during adolescence, although it is greater for males than females at later ages. These findings indicate that prevention interventions may be most effective if they target early adolescence when environmental factors account for the majority of variance in substance use.

The high correlation of genetic factors across ages suggests that early use may sometimes signal an early expression of a developmentally stable genetic predisposition.

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