Mild Cognitive Impairment in Early Parkinson's Disease Using the Movement Disorder Society Task Force Criteria: Cross-Sectional Study in Hoehn and Yahr Stage 1.

Background: Mild cognitive impairment (MCI) in Parkinson's disease (PD) is common and confers a higher risk for developing dementia.

Methods: In this cross-sectional study of MCI in PD conducted at a university hospital, a comprehensive neuropsychological battery covering five domains (attention/working memory, executive, verbal, and visual memory, language, and visuospatial) was administered to 111 nondemented PD patients in Hoehn and Yahr stage 1 and to 105 healthy matched control subjects (HC). MCI was diagnosed according to level 2 of the Movement Disorder Society Task Force criteria.

Results: Criteria for MCI associated with PD (PD-MCI) were fulfilled by 24% of PD patients in the initial stage of the disease at the z cutoff scores of -1.5 SD in contrast to 7% of HC fulfilling criteria for MCI. Memory and visuospatial domains were the most commonly affected at -1.5 SD. PD-MCI patients mostly had a multiple-domain MCI subtype (78%). They presented a more severe bradykinesia and higher mood and apathy scores in comparison with cognitively normal PD patients. Basic motor scores predicted performance on some cognitive tests and specific cognitive-motor relationships emerged.

Conclusions: MCI, predominantly of a multiple-domain subtype, was quite prevalent even in the initial stage of PD.