Personality Dimensions Measured by the Temperament and Character Inventory in Male Subjects with Substance-Related Disorders

Objective：Substance abusers are known to typically differ from the general population in several personality characteristics. However, it is unclear if a single personality type is prone to addiction and if individual differences in personality are associated with a type of substance use disorder. Methods：To investigate these points, we assessed the personality dimensions of single-substance-(metha-mphetamine) and polysubstance (including methamphetamine)-dependent subjects as well as a healthy control group. Eighty-six male subjects with methamphetamine dependence and 37 subjects with polysubstance dependence, who had all been abstinent from illegal drugs for at least 30 days, along with 48 healthy male control subjects were examined using the structured clinical interview for the DSM-IV, the temperament and character inventory, the Beck Depression Inventory, the State-Trait Anxiety Inventory, and the Alcohol Use Disorders Identification Test. Results：Novelty seeking and self-transcendence were significantly higher in both the methamphetamine and polysubstance groups than in the control group (p<0.001 and p=0.013, respectively). Self-directedness was the lowest in the polysubstance group compared to the methamphetamine and control groups (p=0.002). Conclusions：Our findings demonstrate that male subjects with a substance use disorder may have distinct temperament and character dimensions compared to healthy controls. In addition, polysubstance abusers have lower self-directedness, suggesting a possible problem in personality, than single-substance methamphetamine abusers.