Early barbiturate exposure: the brain, sexually dimorphic behavior and learning.

Barbiturates, one of the most widely prescribed and abused classes of drugs, reportedly have been prescribed in as many as 25% of pregnancies in the U.S. and Europe over the last 30 years. Nevertheless, there exists little if any data on long-term consequences of prenatal exposure to barbiturates in humans. Evidence from laboratory animals indicates that exposure to barbiturates during early developmental periods results in abnormal neural and biochemical differentiation of the central nervous system, deficits in learning, retarded attainment of developmental milestones, alteration of behavioral and physiological sex differences, increased activity, and decreased responsiveness to aversive and appetitive stimuli. Barbiturates appear to influence the brain via two routes: (1) by direct action on neural tissue; and (2) indirectly by altering hepatic metabolism of steroid hormones. It is concluded that prenatal exposure to barbiturates in human subjects may lead to learning disabilities, decreased IQ, performance deficits, increased incidence of psychosocial maladjustment, and demasculinization of gender identity and sex role behavior in males.