Punding in Parkinson's Disease: An Update.

Background: Punding is a stereotyped behavior characterized by an intense fascination with a complex, excessive, non-goal oriented, repetitive activity affecting individuals with Parkinson's disease (PD) on dopamine replacement therapy (DRT). Objectives: In 2010, we published the first review focused on the pathophysiology of punding. This study aims to systematically review the literature of the past decade on punding in PD, particularly focusing on the clinical features, underlying pathophysiological mechanisms, and treatment. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we searched PubMed, Embase, and APA PsycInfo for articles published between July 1, 2010 and March 19, 2022. The search strategy included: (punding) AND (parkinson*). Results: Of 256 studies identified, 29 were eligible for inclusion with 19 original research articles and 10 case reports. This review confirmed that predictors of punding in PD are higher doses of DRT, younger age, male sex, and increasing disease severity. We also found an association between punding and psychiatric and/or cognitive symptoms. Neuroimaging studies have showed that punding in PD is associated with a disconnection between midbrain, limbic and white matter tracts projecting to the frontal cortices and a breakdown of the connectivity among the crucial nodes of the reward circuit. Low-frequency repetitive transcranial magnetic stimulation on the dorsolateral prefrontal cortex has been shown to produce a transient beneficial effect in PD patients with punding. Conclusion: In conclusion, although the clinical features of punding have been established, in the past 12 years, we gained a better understanding of the pathophysiological mechanisms of punding, mainly thanks to magnetic resonance imaging techniques.