Characterizing mild cognitive impairment in Parkinson's disease

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Growing interest in identifying Parkinson's disease with mild cognitive impairment (PD-MCI).
• Current diagnostic criteria for PD-MCI are widely disparate, leading to inconsistent identification.
• Accurate identification of PD-MCI is essential for understanding disease progression and developing targeted interventions.

Purpose of the Study:

• To assess the influence of different neuropsychological criteria on the identification of PD-MCI.
• To compare the distribution of cognitive performance in PD-MCI groups relative to control and Parkinson's disease with dementia (PD-D) groups.
• To propose suitable criteria for minimizing the inclusion of cognitively well patients in PD-MCI diagnoses.

Main Methods:

• Evaluated 143 Parkinson's disease patients and 50 matched controls on 20 cognitive measures across four domains.
• Classified non-demented PD patients using 12 different neuropsychological criteria for mild cognitive impairment (MCI).
• Compared the impact of these criteria on the proportion of identified PD-MCI cases and cognitive performance distributions.

Main Results:

• Different criteria resulted in substantial variation in PD-MCI case identification, ranging from 14% to 89%.
• Criteria requiring 2 specific deficit scores or deficits across 2 domains better balanced the identification of impaired and unimpaired cognition.
• Suggested criteria of 2 scores at -1.5 SD within a single domain (30% PD-MCI) or 1 score at -1.5 SD in each of 2 domains (37% PD-MCI) showed promise.

Conclusions:

• The choice of diagnostic criteria significantly impacts the identification rates of PD-MCI.
• Criteria balancing deficit scores and domain involvement are recommended for accurate PD-MCI identification.
• Proposed criteria using standardized scores (-1.5 SD) offer a more reliable approach to minimize misclassification of cognitively healthy individuals.