Background: Impulsive compulsive behavior (ICB) often disturb patients with Parkinson's Disease (PD), of which impulse control disorder (ICD) and dopamine dysregulation syndrome (DDS) are two major subsets. Although the nucleus accumbens (NAcc) is involved in ICB, it remains unclear how the NAcc affects cortical function and defines the different behavioral characteristics of ICD and DDS. Objectives: To identify the most involved cortico-striatal network in ICB and the differences in these networks between patients with ICD and those with DDS using structural and resting-state functional magnetic resonance imaging. Methods: Patients with PD were recruited using the data from a previous cohort study and were divided into patients with ICB (ICB group) and those without ICB (non-ICB group) using the Japanese version of the Questionnaire for Impulsive Compulsive Disorders in Parkinson's Disease (J-QUIP). From these two groups, we extracted 37 pairs matched for age, sex, disease duration, and levodopa equivalent daily dose of dopamine agonists. Patients with ICB were further classified as either having ICD or DDS based on the J-QUIP subscore. General linear models were used to compare the gray matter volume and functional connectivity (FC) of the NAcc, caudate, and putamen between the ICB and non-ICB groups and between patients with ICD and those with DDS. Results: We found no significant differences in gray matter volume between the ICB and non-ICB groups or between patients with ICD and those with DDS. Compared with the non-ICB group, the FC of the right NAcc in the ICB group was lower in the bilateral ventromedial prefrontal cortex and higher in the left middle occipital gyrus. Patients with DDS showed higher FC between the right putamen and left superior temporal gyrus and higher FC between the left caudate and bilateral middle occipital gyrus than patients with ICD. In contrast, patients with ICD exhibited higher FC between the left NAcc and the right posterior cingulate cortex than patients with DSS. Conclusions: The functionally altered network between the right NAcc and ventromedial prefrontal cortex was associated with the presence of ICB in PD, and the surrounding cortico-striatal networks may differentiate between the behavioral characteristics of patients with ICD and those with DDS.

The authors have declared no competing interest.

This study was supported by Grants-in-Aid from the Research Committee of Central Nervous System Degenerative Diseases, Research on Policy Planning and Evaluation for Rare and Intractable Diseases, Health, Labor and Welfare Sciences Research Grants, the Ministry of Health, Labor and Welfare, Japan (Grant number: 20FC104).

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Osaka University clinical research review committee of Osaka University Hospital (Approval number: 13471-12)

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