Is either anosmia or constipation associated with cognitive dysfunction in Parkinson's disease?

Area of Science:

• Neuroscience
• Neurology

Background:

• Parkinson's disease (PD) is a neurodegenerative disorder affecting motor function.
• Early non-motor symptoms like anosmia and constipation are common in PD.
• Understanding the relationship between these symptoms and cognitive function is crucial for early diagnosis and management.

Purpose of the Study:

• To investigate the association between anosmia (loss of smell) and constipation with cognitive dysfunction in newly diagnosed Parkinson's disease patients.
• To determine the relationship between these non-motor symptoms and the severity of PD motor symptoms.

Main Methods:

• A cohort of 107 newly diagnosed PD patients (disease duration < 5 years) was studied.
• Patients were assessed for anosmia and graded for constipation severity.
• Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA), and PD motor severity was measured by the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS).

Main Results:

• Lower MoCA scores were observed in patients with anosmia (p < 0.001).
• Anosmia and older age were significant predictors of cognitive dysfunction (MoCA < 26).
• Patients with anosmia showed higher MDS-UPDRS part 3 scores, and those with grade 3 constipation had higher overall MDS-UPDRS scores.

Conclusions:

• Anosmia is significantly associated with cognitive impairment in Parkinson's disease patients.
• Severe constipation is linked to impaired olfaction and increased PD disease severity.
• The findings suggest distinct yet complex intercommunication pathways for alpha-synuclein propagation in PD, potentially involving olfactory and enteric nervous systems.