Clinical Scorecard: Serotonin System Impairment in Parkinson's Disease Patients with Impulse Control Disorders

At a Glance

Key Highlights

• PDICD+ patients exhibit greater presynaptic serotonin transporter (SERT) availability in posterior putamen and pallidum compared to PDICD− patients.
• Increased cortical 5-HT2A receptor binding in sensorimotor and associative networks involved in behavioural inhibition is observed in PDICD+ patients.
• Serotonergic dysfunction in PDICD+ specifically involves sensorimotor and associative cortico-striato-pallido-thalamic circuits, contributing to impaired inhibitory control beyond dopaminergic abnormalities.

Guideline-Based Recommendations

Diagnosis

• Consider clinical assessment of ICD symptoms including hypersexuality, compulsive eating, shopping, and gambling in PD patients.
• Use PET imaging with 11C-DASB and 18F-altanserin tracers to evaluate serotonergic system involvement in research or specialized centers.

Management

• Individualize management of ICDs in PD, addressing dopaminergic treatment exposure and comorbid neuropsychiatric conditions such as anxiety and depression.
• Employ cognitive behavioural therapy and involve patient care partners to mitigate social repercussions.
• Avoid abrupt dopaminergic drug withdrawal to prevent withdrawal syndrome with motor and non-motor worsening.

Monitoring & Follow-up

• Regularly monitor for emergence or worsening of ICD symptoms in PD patients, especially those on dopamine agonists.
• Assess neuropsychiatric symptoms including depressive and anxious features that may exacerbate ICDs.

Risks

• Dopaminergic treatments, particularly dopamine agonists, increase risk of ICD development and persistence.
• Reduction or cessation of dopaminergic drugs may lead to withdrawal syndrome with apathy and anxiety.
• ICDs can cause significant distress and negative social and personal consequences.

Patient & Prescribing Data

Parkinson’s disease patients with and without impulse control disorders

Dopaminergic therapies contribute to ICD risk; serotonergic dysfunction represents a potential therapeutic target beyond dopaminergic modulation.

Clinical Best Practices

• Adopt a comprehensive, graded approach to ICD management incorporating pharmacological, psychological, and social interventions.
• Screen for and address comorbid neuropsychiatric symptoms that may influence ICD severity.
• Consider serotonergic system involvement when evaluating ICD pathophysiology and potential novel treatments.
• Use PET imaging selectively in research or specialized clinical contexts to understand serotonergic contributions.

References

• Cilia and Kaasinen Scientific Commentary