Previous studies have shown a link between mood disorders and substance abuse but it is hard to untangle whether the mood disorders cause people to take drugs or their drug taking leads to mood disorders and it has also been hard to find out which particular types of mood disorders cause problems with which particular types of drugs. A study of 591 people in Switzerland which followed them from young adulthood over a twenty-year period looked into the links between different types of mood disorders and substance abuse problems. The researchers found that people with manic symptoms were at greater risk of developing problems with alcohol, cannabis and benzodiazepines later. Bipolar II disorder predicted alcohol and benzodiazepine problems while depression was only linked to problems with benzodiazepines.
Merikangas, Kathleen R. ... [et al] - Specificity of bipolar spectrum conditions in the comorbidity of mood and substance use disorders Archives of General Psychiatry January 2008, 65(1), 47-52