Addiction and the Bipolar Spectrum

Dual Diagnosis With a Common Substrate?

Abstract

Drug addiction has been correctly assigned to the field of mental illness, due to the nature of its symptoms, clinical picture, and its pathophysiological pathways within the central nervous system. Some similarities have emerged between addictive symptoms and psychiatric diseases such as hypomania and impulse control disorders, including borderline and antisocial personality disorders (for all of which we envisage a common genetic diathesis). Nevertheless, once established, addiction exhibits an autonomous process, and the coexistence with other mental disorders represents a condition of dual diagnosis. The co-existence with other mental disorders shares neurobiological ground on which certain psychopathologic dispositions impart an enhanced risk of becoming addicted. In particular, we suggest that the bipolar spectrum-and its hyperthymic and cyclothymic temperamental substrates-is at special risk for substance use, possibly stepping toward addiction through enduring exposure to intrinsically dependence-producing substances. In our experience, the contribution of bipolarity to the addictive process is often missed because subclinical expressions of bipolarity along temperamental extremes are insufficiently appreciated by both psychiatrists and addictionologists. Finally, the use of agonist treatment in dual diagnosis heroin addicts has allowed us to gather valuable knowledge about their intrinsic, and historically and clinically documented, mood-regulating effects. We submit that the present conceptualization of the link between addictive and bipolar disorders has heuristic clinical and scientific merits.