Penn/VA center for studies of addiction

Tales from the dark side: do neuromodulators of drug withdrawal require changes in endocannabinoid tone?

Environmental and interoceptive cues are theorized to serve as 'signals' that motivate drug seeking and effects that may be augmented in the withdrawn state. Phasic dopamine release events are observed in the nucleus accumbens in response to such motivational salient stimuli and are thought to be necessary for drug-associated cues to trigger craving. We recently demonstrated how dopamine neurons encode stimuli conditioned to a negative event, as might occur during conditioned withdrawal, and stimuli predicting the avoidance of negative events, as might occur as an addict seeks out drugs to prevent withdrawal. In this review we first discuss how the subsecond dopamine release events might process conditioned withdrawal and drug seeking driven by negative reinforcement processes within the context of our dopamine data obtained during conditioned avoidance procedures. We next describe how the endocannabinoid system modulates phasic dopamine release events and how it might be harnessed to treat negative affective states in addiction. Specifically, we have demonstrated that endocannabinoids in the ventral tegmentum sculpt cue-induced accumbal surges in dopamine release and, therefore, may also be mobilized during drug withdrawal.

Diagnostic disagreements in bipolar disorder: the role of substance abuse comorbidities

Substance abuse can produce symptoms similar to other psychiatric disorders, thus confusing the diagnostic picture. This paper attempts to elucidate how misdiagnosis in bipolar disorder might be explained by the presence of substance abuse comorbidities. The overlap of symptoms, limited information about symptom onset, and inexperienced clinicians can result in the misinterpretation of symptoms of substance abuse disorders for bipolar disorder. The present study found that the presence of a substance abuse comorbidity, the polarity of last episode (depressed, manic, mixed, not otherwise specified), and the total number of comorbidities affected the reliability of a bipolar disorder diagnosis.