The purpose of the current study was to investigate the relationship between substance use and bipolar disorder, specifically whether comorbid substance use could predict the diagnostic classification of bipolar disorder (bipolar Ior II). The investigation was based on a secondary analysis of archival data from the Collaborative Psychiatric Epidemiological Surveys (CPES). The researcher hypothesized that the psychobiological effects of substance abuse could account for the high prevalence of bipolar disorder and comorbid substance abuse. This was thought to be particularly true for drug abuse which can produce symptoms that mimic bipolar disorder. Gender was included in order to identify any significant differences among males and females.

Results indicated that bipolar I was associated with an increased risk of comorbid substance abuse, particularly drug abuse. There was a significant association between bipolar I and comorbid drug abuse in the female sample compared with bipolar II. A statistically significant association between comorbid drug and alcohol abuse combined and bipolar I provided further evidence supporting the positive relationship between bipolar I and comorbid substance abuse.

Logistic regressions were run on comorbidity of substance abuse and bipolar disorder diagnoses. Participants who had a bipolar I diagnosis were found to be almost four times more likely to have comorbid drug abuse than were those with bipolar II. Females with bipolar disorder were found to be four times less likely to carry a comorbid diagnosis of drug abuse than were their male counterparts. The logistic regression on comorbid alcohol abuse and bipolar disorder was not significant.

The researcher's finding relative to substance use comorbidity among individuals with bipolar I is consistent with previous research. The current study extends previous research with results that indicate that the specific association between bipolar I and drug abuse is more powerful in women, with comorbid substance abuse being more prevalent in men than women across both bipolar disorder categories. Recommendations for future research include a more comprehensive look at the onset and course of each of the respective disorders in relation to gender in order to better understand the relationship between these variables.