Many people begin to drink alcohol during adolescence and young adulthood. Alcohol consumption during this developmental period may have profound effects on brain structure and function. Heavy drinking has been shown to affect the neuropsychological performance (e.g., memory functions) of young people and may impair the growth and integrity of certain brain structures. Furthermore, alcohol consumption during adolescence may alter measures of brain functioning, such as blood flow in certain brain regions and electrical brain activities. Not all adolescents and young adults are equally sensitive to the effects of alcohol consumption, however. Moderating factors-such as family history of alcohol and other drug use disorders, gender, age at onset of drinking, drinking patterns, use of other drugs, and co-occurring psychiatric disorders-may influence the extent to which alcohol consumption interferes with an adolescent's normal brain development and functioning.
KEY WORDS: young adult; adolescent; heavy drinking; alcohol use disorder; brain function; AODR (alcohol and other drug related) structural brain damage; AODR neuropsychological disorder; cognitive development; cognitive ability; cognitive and memory disorder; risk factors; sensitization; causes of AODU (alcohol and other drug use); family AODU history; gender differences; AOD use pattern; age of AODU onset; comorbidity
Several decades of research have shown that chronic heavy drinking is associated with adverse effects on the central nervous system and have revealed some of the processes that give rise to these effects. Yet it remains unclear when in the course of a persons "drinking career" these central nervous system changes may emerge. Recent research suggests that heavy drinking may already affect brain functioning in early adolescence, even in physically healthy youths. This issue is important and interesting for at least two reasons. First, the brain continues to develop throughout adolescence and into young adulthood, and insults to the brain during this period therefore could have an impact on long-term brain function. Consistent with this assumption, animal studies have demonstrated that alcohol exposure during adolescence and young adulthood can significantly interfere with an animals normal brain development and function (for a review, see the accompanying article by Hiller-Sturmhöfel and Swartzwelder). Second, young adulthood is a period when most people make critical educational, occupational, and social decisions, and impaired cognitive functioning at this time could substantially affect their futures.
Questions regarding alcohol's influence on brain development and function during adolescence are especially pertinent because heavy drinking is quite common among young people. For example, in one survey, 36 percent of 19- to 28-year-olds reported having consumed five or more drinks in a row in the preceding 2 weeks (Johnston et al. 2003). Another survey determined that 7 percent of 18- to 25-year-olds meet the diagnostic criteria for alcohol dependence (Substance Abuse and Mental Health Services Administration [SAMHSA] 2003). Thus, a substantial number of adolescents and young adults could be at risk for alcohol-related impairment of brain development and brain function.
This article reviews research on the impact of alcohol on the brains of young adults. It discusses several areas of brain function and development that appear to be affected, describes the extent of the harm observed as well as the factors that appear to moderate alcohol's effects, and identifies high-risk groups of youths who are most likely to incur alcohol-related brain impairment.
EFFECTS ON NEUROPSYCHOLOGICAL PERFORMANCE
One aspect of brain functioning that is commonly studied in youths as well as older adults is neuropsychological performance,1 which includes memory function, attention, visuospatial skills, and executive functioning (e.g. …