Background Exposure to permissive minimum legal drinking age (MLDA) laws not only affects young adults in the short term, but also later in life; for example, individuals who could legally purchase alcohol before the age of 21 are more likely to suffer from drinking problems as older adults, long after the laws had been changed. However, it is not known how permissive MLDA exposure affects specific drinking behavior. This present study uses changes in MLDA laws during the 1970s and 1980s as a natural experiment to investigate the potential impact of permissive MLDA exposure on average alcohol consumption, frequency of drinking, and patterns of binging and more moderate, nonheavy drinking.

Methods Policy exposure data were paired with alcohol use data from the 1991 to 1992 National Longitudinal Alcohol Epidemiologic Survey and the 2001 to 2002 National Epidemiologic Survey on Alcohol and Related Conditions. Past‐year drinkers born between 1949 and 1972 (n = 24,088) were included. Average daily intake, overall drinking frequency, and frequency of both binge episodes (5+ drinks) and days without a binge episode (nonheavy drinking) for the previous year at the time of interview were tracked for each respondent.

Results Exposure to permissive MLDAs was associated with higher odds to report frequent binging and lower odds to report any moderate drinking; these associations were largely driven by men and those who did not attend college. Overall drinking frequency and average alcohol consumption were not affected by MLDA exposure.