Behavioral and neural consequences of prenatal exposure to nicotine

Objective: To review evidence for the neurodevelopmental effects of in uter o exposure to nicotine. Concerns about long-term cognitive and behavioral e ffects of prenatal exposure to nicotine arise from reports of increased rat es of disruptive behavioral disorders in children whose mothers smoked duri ng pregnancy. The relatively high rate of tobacco smoking among pregnant wo men (25% of all pregnancies in the U.S.) underlines the seriousness of thes e concerns. Method: This review examines the largest and most recent epidem iological and clinical studies that investigated the association of prenata l nicotine exposure with health, behavioral, and cognitive problems. Becaus e of the numerous potential confounding variables in human research, findin gs from animal studies, in which environmental factors are strictly control led, are also discussed. Finally, neural and molecular mechanisms that are likely to underlie neurodevelopmental disruptions produced by prenatal nico tine exposure are outlined. Results: A dose-response relationship between m aternal smoking rates and low birth weight (potentially associated with low er cognitive ability) and spontaneous abortion is consistently found, where as long-term developmental and behavioral effects in the offspring are stil l controversial, perhaps because of the difficulty of separating them from other genetic and environmental factors. Despite the wide variability of ex perimental paradigms used in animal studies, common physical and behavioral effects of prenatal exposure to nicotine have been observed, including low birth weight, enhanced locomotor activity, and cognitive impairment. Final ly, disturbances in neuronal pathfinding, abnormalities in cell proliferati on and differentiation, and disruptions in the development of the cholinerg ic and catecholaminergic systems all have been reported in molecular animal studies of in utero exposure to nicotine. Conclusions: Prenatal exposure t o nicotine may lead to dysregulation in neurodevelopment and can indicate h igher risk for psychiatric problems, including substance abuse. Knowledge o f prenatal exposure to nicotine should prompt child psychiatrists to closel y monitor at-risk patients.