Prevalence and profile of mild cognitive impairment in Parkinson's disease

The frequency of mild cognitive impairment (MCI) in Parkinson's disease (PD) ranges from 19 to 40%, and this is probably due to methodological differences between the studies. The aim of this study was to evaluate the frequency and profile of MCI in a large sample of nondemented PD subjects and neurologically healthy subjects (NHS).

A total of 872 subjects (582 controls and 290 PD) were included. The association between MCI and PD was tested, using logistic regression models; odds ratios (OR) with 95% confidence intervals (CI) were calculated.

Fifty-three percent of PD subjects and 45% NHS met the criteria for MCI (p = 0.001). The PD subjects showed a higher frequency of nonamnestic MCI (naMCI), compared to NHS (23.8 vs. 14.4%, p ≤ 0.0001). In comparison to NHS, PD was associated with a univariate OR of 1.9 (95% CI = 1.3-2.8) for naMCI, and this association was marginally significant after multiple comparisons (multivariate OR = 1.5, 95% CI = 0.96-2.3, p = 0.077).

The association between PD and the impairment of nonmemory domains is probably due to frontal-subcortical involvement, which characterizes the disease.