Cocaine abuse and the bipolar spectrum in 1090 heroin addicts: clinical observations and a proposed pathophysiologic model.

BACKGROUND: Several studies indicate a specific relationship between bipolar disorder and stimulant use and abuse. It has generally been assumed that cocaine use represents self-enhancement or attempts to optimize one's level of hypomania, cyclothymia or hyperthymia. This topic required further examination among heroin abusers because cocaine abuse is commonly comorbid with heroin abuse.
METHODS: Cocaine abuse by bipolar subjects was investigated in a group of 1090 treatment-seeking heroin addicts enrolled between 1994 and 2005. We collected data with 1) the Drug Addiction History Rating Scale; and 2) the Semi-structured Interview for Depression, which inquires systematically among others, about hypomania, cyclothymia, hyperthymia and depressive temperament. Subjects were aged 29+/-6 years, and predominantly male (76.2%).
RESULTS: Univariate and multivariate analyses provided correlations in favour of a link between current cocaine abuse and double diagnosis, with special relevance to the bipolar spectrum, as well as psychotic disorders (p<0.0001). LIMITATION: The modality of access to cocaine in different communities and the difficulty to distinguish cocaine use from abuse by the rating scale administered may have limited the interpretation of results.
CONCLUSIONS: If cocaine abuse precedes that of heroin or is concomitant, heroin may hypothetically serve as a "mood balancer" which transiently dampens subthreshold excitatory states and mood swings. Our data further suggest the need for a more complex model linking cocaine and bipolarity: subthreshold bipolarity, including hyperthymic and cyclothymic temperaments, seems to predispose to heroin addiction, but craving for the suppressed hypomania in turn could lead to cocaine abuse, which eventually unmasks a frank bipolar disorder - in some cases leading to mixed state, severe mania, as well as psychosis beyond mania. Prospective observations would shed further insight on this complex interface of major clinical and public health importance.