Individual differences among cocaine users

The present study examined whether individual differences in personality could differentiate two types of cocaine users. We hypothesized that self-medicators (SM) use cocaine as a way to alleviate their dysphoric moods, whereas sensation seekers (SS), in contrast, use cocaine primarily to engender positive mood states. Eighteen male cocaine users were classified based on two dimensions of the Tridimensional Personality Questionnaire. SM were defined by having high harm avoidance (>17) and low novelty-seeking scores (<18), and SS by high novelty-seeking (>18) and low harm-avoidance scores (<17). It was predicted that SM would report higher depression and anxiety than would SS, and would also exhibit a brain activity pattern similar to that found in clinical depression. The results showed that SM reported higher anxiety than SS, F(1, 8) = 27.5, p < .001, but did not differ in depression. SM exhibited decreased blood flow within the left frontal lobes, F(1, 10) = 6.78, p < .05, similar to what has been observed in major depressive disorder. These findings suggest the importance of attending to individual differences in the motivation for cocaine use so that treatment can be targeted more effectively.