A study in the February 2000 Alcoholism: Clinical and Experimental Research (Volume 24, Number 2) presents the first concrete evidence that protracted, heavy alcohol use can impair brain function in adolescents. It is unclear at present whether the damage is reversible.
Supported by the National Institute on Alcohol Abuse and Alcoholism, a research team led by Sandra A. Brown, Ph.D., chief of psychology at the VA San Diego Healthcare System and professor of psychology and psychiatry at the University of California, San Diego, assessed neuropsychological function in thirty-three 15- and 16-year-old adolescents with more than 100 lifetime alcohol use episodes and without dependence on other drugs. The alcohol dependent teens were recruited from inpatient treatment programs and compared after a minimum of 3 weeks of abstinence with twenty-four age, gender, socioeconomic status, and education-matched adolescents with no history of alcohol or other drug problems. Through structured clinical interviews corroborated by parent reports, the researchers assessed both groups for recent and lifetime involvement with alcohol and other drugs, alcohol or other drug disorders, and alcohol or other drug withdrawal symptoms. Both groups then participated in psychological tests of learning, memory, visuospatial functioning, language skills, problem solving, and attention.
"Significant brain development continues through adolescence," said Dr. Brown. "For example, certain brain nerve cell connections disappear up until about age 16 as a function of environmental stimulation and redundancy, and cerebral metabolic rates increase in childhood, then taper toward adult levels by about age 20. Thus, alcohol may have quite different toxic effects on adolescent brains than on those of adults."
But, while adolescent neurological and cognitive development may be disrupted, altered or impeded by exposure to alcohol, young brains have more resilience and more opportunities for compensatory development, Dr. Brown added.
Dr. Brown and her colleagues found several differences in memory function between the alcohol dependent and the control adolescents. Adolescents who had drunk heavily over time scored lower on verbal and nonverbal retention in the contexts of intact learning and recognition discriminability. Recent alcohol withdrawal was associated with poor visuospatial functioning, while lifetime alcohol withdrawal was associated with poorer retrieval of verbal and nonverbal information.
The study has several limitations, the authors point out: An example is that longitudinal studies will be required to determine the direction of the alcohol and neurocognitive relationship. "While protracted alcohol involvement may cause neuropsychological impairment, it also is probable that cognitive deficits are a risk factor for alcohol disorders," said Dr. Brown. In addition, the use of other drugs may have affected cognitive performance. "None of our heavy drinking adolescents was dependent on other drugs, although all reported some exposure, especially to marijuana and stimulants. On the basis of animal research by others, we would expect that heavy alcohol use alone can produce behavioral abnormalities in humans."
"This work is an important step toward confirming what many scientists have suspected for some time," said NIAAA Director Enoch Gordis, M.D. "Certainly, it raises important questions for researchers and, if borne out by additional studies, for young people, parents, educators, and policy makers."
"Of course, other consequences associated with underage drinking-interference with learning, social, other competencies, fatal traffic crashes, unintentional injuries, homicide, suicide, and early, more frequent, and less safe sexual activity--already are well known. Initiatives to keep youth alcohol free and define research-based interventions for college drinking are current NIAAA priorities."
"Our youth are an especially vulnerable part of America's alcohol problem," said Dr. Gordis. "It is time that we face underage drinking head on."
Coauthors of the study are Susan F. Tapert, Ph.D., Eric Granholm, Ph.D., and Dean C. Delis, Ph.D., Psychology Service, VA San Diego Healthcare System and Department of Psychiatry, University of California, San Diego. The Veterans Medical Research Service and the National Institute of Mental Health contributed additional support for the study.
For an interview with Dr. Brown, contact (telephone) 858/822-1887. For an interview with Dr. Gordis, contact NIAAA Press (telephone) 301/443-3860. For additional alcohol research information and publications, visit http://www.niaaa.nih.gov.