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Impulse control disorders are named for their essential feature: the failure to resist an impulse, drive or temptation to perform a harmful act. Whether the diagnosis is pathological gambling, kleptomania, pyromania, trichotillomania, intermittent explosive disorder, binge eating or compulsive buying, the affected individual is unable to voluntarily control, cut back or stop the undesirable behavior. The treatment of patients with disorders of impulse control presents a challenge to the psychiatrist, and the study of maladaptive behavior seen in drug addiction can be informative.
Drug addiction refers to compulsive drug use despite adverse consequences, loss of control over the amount and frequency of drug use, irresistible cravings and urges, denial of indisputable harmful effects, and the emergence of dysphoria or irritability when the drug is absent (Heidbreder, 2005). The comparison of drug addiction and impulse control disorders, in terms of underlying mechanism of disease, psychiatric comorbidity and treatment modalities, can lead to improved understanding of the treatment of impulse control disorders.
Current work in the field of drug addiction involves continued elucidation of the neurobiological underpinnings of drug intake, craving and relapse. According to the opioid/dopamine (DA) hypothesis of drug addiction, most drugs of abuse appear to elicit a sustained increase in extracellular DA in the mesolimbic system that originates in the ventral tegmental area (VTA) of the frontal lobe and projects toward the limbic forebrain regions, including the nucleus accumbens (NAc) (Nutt, 1996). Dopamine release in terminal projection areas of the mesolimbic system appears to be associated with the processing of reward and pleasure, and the NAc has been termed the brain reward center (Schultz, 1997). This theory posits, therefore, that drugs of abuse cause changes in the VTA and NAc that reinforce drug-related cues and lead to drug cravings and increased drugseeking behavior.
Cravings have also been described as a feature of impulse control disorders. For example, in pathological gambling, binge eating and compulsive buying, patients experience strong urges and cravings to engage in the maladaptive behavior. In contrast to addictive disorders, the cravings of impulse control disorders are not due to the influence of exogenous drug effects on brain substrates. It has been proposed that cravings and urges associated with impulse control disorders may be due to underlying brain serotonin dysregulation (Potenza, 2001).