Reduced dopamine transporter binding predates impulse control disorders in Parkinson's disease

Area of Science:

• Neuroscience
• Neurology
• Radiology

Background:

• Impulse control disorders (ICD) are common in Parkinson's disease (PD), often linked to dopamine replacement therapy.
• Previous studies suggested reduced dopamine transporter (DAT) binding in PD patients with ICD, but these were in patients with pre-existing impairments.
• Understanding baseline neurobiology is crucial for predicting ICD development in PD.

Purpose of the Study:

• To investigate whether baseline dopamine transporter (DAT) availability predicts the development of impulse control disorders (ICD) in medication-naïve Parkinson's disease (PD) patients after initiating dopamine replacement therapy.
• To identify neurobiological risk factors for ICD in PD.

Main Methods:

• Retrospective analysis of 31 medication-naïve PD patients who underwent baseline dopamine transporter (DAT) SPECT imaging.
• Follow-up assessment of medication status and ICD symptom development over approximately 31.5 months using questionnaires and interviews.
• Comparison of baseline DAT availability between PD patients who developed ICD and those who did not.

Main Results:

• Eleven out of 31 PD patients developed ICD symptoms during follow-up, with eight taking dopamine agonists.
• Patients who developed ICD had higher baseline depressive scores and lower baseline DAT availability in the right ventral striatum, anterior-dorsal striatum, and posterior putamen compared to those without ICD.
• ICD symptom severity negatively correlated with baseline DAT availability in the right ventral and anterior-dorsal striatum.

Conclusions:

• Reduced striatal dopamine transporter availability precedes the development of impulse control disorders (ICD) in Parkinson's disease (PD) patients after dopamine replacement therapy.
• Lower premorbid DAT availability or more pronounced dopamine denervation may represent a neurobiological risk factor for ICD susceptibility in PD.
• Baseline DAT SPECT imaging could aid in identifying PD patients at risk for developing ICD.