In a systematic review of current evidence published in PLoS Medicine, the authors-Jim McCambridge from the London School of Hygiene & Tropical Medicine, London, and colleagues-conclude that there is enough evidence to support the theory that reducing drinking during late adolescence is likely to be important for preventing long-term adverse consequences of drinking, as well as protecting against more immediate harms.
Although there is an urgent need for better studies in this area, research to date provides some evidence that high alcohol consumption in late adolescence often continues into adulthood and is associated with long-term alcohol problems, including dependence.
The authors of the current study conducted a comprehensive literature review to identify 54 relevant studies which included at least one quantitative measure of the effects of alcohol, on outcomes in adulthood such as death, alcohol dependence, criminal offences, mental health, educational attainment, and smoking. The majority of these studies were multiple reports from ten cohorts, half of which were from the US.
The authors found that although there is consistent evidence that higher alcohol consumption in late adolescence continues into adulthood and is associated with alcohol and other problems, most of these studies could not strongly support direct causality because of their weak designs.  Furthermore, although a number of studies suggested links with late adolescent drinking to adult physical and mental health and social consequences, the evidence is generally of poorer quality and is insufficient to infer causality.

Source: McCambridge J, McAlaney J, Rowe R (2011) Adult Consequences of Late Adolescent Alcohol Consumption: A Systematic Review of Cohort Studies. PLoS Med 8(2): e1000413. doi:10.1371/journal.pmed.1000413