Impulse Control Disorders and Dopaminergic Drugs—Reply

In reply

We appreciated the interest in our article¹ by Dr Morgan and colleagues. We agree that any drug that increases cerebral dopaminergic neurotransmission may facilitate development of impulse control disorders. We specifically focused on pathological gambling, however, and were struck by the association with dopamine agonist therapy and most notably pramipexole. As we commented in our article, levodopa may have been a contributory factor, and that seems likely in those cases where agonists were adjunctively administered.

Levodopa has been the foundation of PD treatment for decades, often as monotherapy. However, none of our patients in the study with pathological gambling or those in prior published series were treated with levodopa monotherapy; all were taking therapeutic doses of agonists. As we indicated in our article, Molina et al² failed to specify drugs other than levodopa: adjunctive drugs were employed but not listed; hence, we could not include their series in our compilation.

We thank Dr Morgan and colleagues for bringing to our attention the abstract by Tyne et al,³ who did report pathologic gambling in a single patient on levodopa monotherapy, although their other 6 pathologic gamblers were taking dopamine agonists. They also commented, “In those discontinuing dopamine agonist therapy the urge to gamble ceased quickly.”³

For the reasons discussed in our article, disproportionate dopamine D₃ agonism as a substrate for pathologic gambling seems too obvious to ignore. Effective risperidone treatment of pergolide-associated pathologic gambling⁴ cited by Dr Morgan and colleagues is consistent, given that risperidone is also a potent dopamine D₃ antagonist.⁵

Correspondence: Dr Dodd, Department of Psychiatry and Psychology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (dodd.maryellen@mayo.edu).