Impulsivity and apathy in Parkinson's disease

Area of Science:

• Neuroscience
• Psychiatry
• Movement Disorders

Background:

• Impulse control disorders (ICDs) and apathy are significant neuropsychiatric syndromes in Parkinson's disease (PD).
• The underlying cognitive mechanisms for ICDs and apathy in PD remain poorly understood.
• Existing research suggests a link between these conditions and dopamine-dependent motivated decision-making.

Purpose of the Study:

• To review current findings on the cognitive mechanisms of ICDs and apathy in Parkinson's disease.
• To propose a new conceptual framework for understanding these conditions as multi-dimensional syndromes.
• To explore the role of dopamine and other dissociable mechanisms in the manifestation of impulsivity and apathy.

Main Methods:

• Review of human and animal studies on impulse control disorders and apathy in Parkinson's disease.
• Analysis of neurobiological and behavioral evidence related to motivated decision-making.
• Synthesis of findings to develop a new conceptual framework.

Main Results:

• Evidence suggests apathy may be linked to a hypodopaminergic state in PD, while ICDs may be associated with dopamine therapy.
• A simple dopaminergic explanation is insufficient; both ICDs and apathy appear to be multi-dimensional syndromes.
• These syndromes may arise from dissociable deficits in cognitive processes like option generation, selection, initiation, inhibition, and learning.

Conclusions:

• Impulsivity and apathy in Parkinson's disease represent opposite extremes of a spectrum influenced by dopamine.
• These conditions are complex and likely involve multiple, dissociable cognitive mechanisms.
• A new framework is proposed to understand the varied functional deficits observed in PD patients with ICDs or apathy.