Stereotyped behavior or punding in Parkinson's disease

Abstract

In patients with Parkinson's disease (PD) disabling repetitive behaviors (stereotyped behaviors or punding) sometimes appear during the course of the illness. Since similar behavioral disorders can be observed in amphetamine and cocaine abusers, excessive dopaminergic tone might have a prominent role in the induction of punding. Dopamine-dependent stereotypy in animals might be a good model for understanding the pathophysiological mechanism underlying stereotyped behaviors induced during dopamine-replacement therapy. In addition to excessive stimulation of dopamine receptors, other factors might also contribute to the generation of dopamine-dependent stereotypy. Such factors include increased sensitivity of dopamine receptors and alteration of synaptic transmission (plasticity) or the striosome-predominant pattern of information processing in the striatum. Clinically, PD patients who exhibit punding often have common characteristics such as relatively younger onset, longer duration of dopamine-replacement therapy, and a higher dose of levodopa or dopamine agonists used. Thus in the treatment of PD patients with such risk factors, attention should be paid to punding because this feature might not be so rare and could possibly be overlooked. Further studies are required to evaluate and manage this type of behavioral disorder in patients with PD.