THE ROLE OF DRUG AND ALCOHOL-ABUSE IN RECENT INCREASES IN DEPRESSION IN THE US

Previous studies have reported an increase in depression among recent birth cohorts. Concurrent with the increase in rates of depression, th ere have been increases in rates of drug and alcohol abuse and depende nce. This study sought to determine if the recent increase in rates of depression could be attributed to co-mol-bid alcohol and drug abuse. The data derived from two studies: (1) a sample of relatives of proban ds with affective disorder; and (2) a community survey of the US popul ation. The piecewise exponential statistical model was applied to eval uate the association of gender, age, period and birth cohort with rate s of major depressive disorder (MDD) separately for those with, and wi thout, diagnoses of alcohol or drug abuse. Elevated rates of MDD occur red among those with co-morbid drug and alcohol abuse in both the fami ly and community samples. However, there were also temporal increases in rates of MDD in those with no such co-morbidity. Specifically there were effects of age and gender for both studies; in addition, there w as a period effect in the family study and a birth cohort effect in th e community sample. The recent increases in depression in the US canno t be accounted for solely by concurrent increases in co-morbid drug an d alcohol abuse. Temporal (period and cohort) effects on rates of depr ession occur in addition to the contribution of co-morbid drug and alc ohol abuse or dependence.