Researchers at the National Institute on Alcohol Abuse and Alcoholism and the National Institute of Child Health and Human Development report in the current issue of Alcoholism: Clinical and Experimental Research (Volume 24, Number 5) results from the first study to determine whether future drinking may be predicted by response to stress during infancy. Monkeys that responded with high cortisol concentrations to stress during infancy were more likely than their peers to drink alcohol as adults, the research team found.
"Both drinking behavior and an individual's response to stress are determined by multiple genetic and environmental factors," said National Institute on Alcohol Abuse and Alcoholism Director Enoch Gordis, M.D. "If borne out in humans, these findings elucidate the alcohol-stress relationship in two ways: They confirm that early life stress can influence later alcohol consumption, and they offer a promising biological marker of risk for excessive drinking."
"This research may one day lead to ways to prevent alcohol abuse in adults, as well as prevent the devastating effects of alcohol on the developing fetus," said Duane Alexander, M.D., Director of the National Institute of Child Health and Human Development (NICHD). "It is indeed a promising finding."
Led by J. Dee Higley, Ph.D., Laboratory of Clinical Studies-Primate Unit, NIAAA, and Stephen Suomi, Ph.D, Chief, Laboratory of Comparative Ethology, NICHD, and funded by NIAAA, NICHD, and the Swedish Medical Research Council, the researchers followed 97 rhesus macaques from birth to young adulthood. Forty monkeys were separated from their mothers at birth and placed in a neonatal nursery for the first month of life. After 30 days, these monkeys were caged with 3 age-matched peers. Meanwhile, the other 57 monkeys under study remained with their mothers.
When the monkeys were 6 months of age, they were separated briefly from their mothers or peers to test the response to stress. Each monkey was placed into a separation cage where it could hear and see but not touch other monkeys. After separation, blood tests were used to measure plasma cortisol concentration. The researchers found that the stress of separation caused the average cortisol concentration to double. Although cortisol levels in both peer-reared and mother-reared monkeys increased in response to separation, the mean cortisol concentration for peer-reared monkeys was significantly higher than the mean cortisol concentration for mother-reared monkeys.
When the monkeys were young adults (3 to 5 years of age), they were observed for differences in voluntary alcohol consumption. Each monkey had access to alcohol at a drinking station unit, a clear, enclosed perch that enabled the animal to drink without interference from other monkeys. Water was freely available during the periods that the alcohol solution was dispensed. Monkeys that responded to separation as infants with high cortisol levels drank significantly more alcohol as adults than did low-cortisol responders. On average, the adult peer-reared monkeys drank more alcohol than did the mother-reared monkeys.
"These results extend the findings of earlier studies that found that cortisol doubles or triples after separation," said Dr. Higley. "Today's study is the first to follow the monkeys to young adulthood, assess the impact on future drinking behavior, and show that high cortisol levels predict high alcohol consumption in young adults."
For interviews with Dr. Gordis and Dr. Higley, telephone NIAAA Press (301/443-3860). For interviews with Dr. Suomi, telephone NICHD (301/496-5133). Additional alcohol research information and publications are available at http://www.niaaa.nih.gov/.