Hallucinations in Parkinson disease.

Area of Science:

• Neuroscience
• Ophthalmology
• Psychiatry

Background:

• Parkinson disease (PD) patients frequently experience hallucinations and illusions, particularly visual ones.
• Visual hallucinations (VHs) affect about one-third of PD patients cross-sectionally, potentially rising to 75% over 20 years.
• These perceptual disturbances significantly impact psychosocial well-being and can necessitate institutionalization.

Purpose of the Study:

• To review the epidemiology, phenomenology, pathophysiology, and therapeutic options for hallucinations in Parkinson disease.
• To consolidate current knowledge on VHs and other sensory disturbances in PD.
• To highlight the need for improved diagnostic and therapeutic approaches.

Main Methods:

• Review of existing epidemiological, clinical, and neuroimaging studies on hallucinations in PD.
• Analysis of proposed pathophysiological mechanisms, including neurotransmitter imbalances and visual pathway dysfunction.
• Evaluation of current and potential treatment strategies.

Main Results:

• VHs are highly prevalent in PD, with significant long-term incidence.
• Multiple mechanisms contribute to VHs, including dopaminergic and cholinergic dysregulation, visual pathway abnormalities, sleep-wake disturbances, and attentional deficits.
• Limited evidence supports treatments, with clozapine being the only atypical neuroleptic with evidence in non-demented PD patients.

Conclusions:

• Hallucinations in PD are complex phenomena with multifactorial causes.
• Phenomenological characterization and neuroimaging are essential for refining treatment.
• Further research is needed to develop effective therapeutic strategies for VHs in Parkinson disease.