The association between earlier marijuana use and subsequent academic achievement and health problems: a longitudinal study.

In this prospective longitudinal study, the authors investigated the association between marijuana use over a period of 13 years and subsequent health problems at age 27. A community sample of 749 participants from upstate New York was interviewed at mean ages of 14, 16, 22, and 27 years. Marijuana use over time was significantly associated with increased health problems by the late twenties, including respiratory problems, general malaise, neurocognitive problems, and lower academic achievement and functioning. Effective prevention and intervention programs should consider the wide range of adverse physiological and psychosocial outcomes associated with marijuana use over time.