Mild cognitive impairment in Parkinson's disease: subtypes and motor characteristics.

The aims of this project were to determine the risk factors for and clinical characteristics of mild cognitive impairment (MCI) in Parkinson's disease (PD). We performed a retrospective record review of 72 non-demented PD patients (age: 57.79 +/- 10.57, duration of PD: 7.32 +/- 4.97) who completed a standardized neurological assessment, including a full neuropsychological battery, as part of their diagnostic work-up. Of these participants, 47.2% were cognitively normal and 52.8% met criteria for MCI. The majority of MCI patients had single domain MCI (23/38), the affected domains being memory (n = 9), executive function (n = 6), visuospatial skills (n = 6), and language (n = 2). The MCI group had longer duration of disease and higher postural instability and gait disorder subscale scores than the cognitively normal group. This report provides further support for use of the concept of MCI in PD research. There may be certain disease characteristics that could alert practitioners to the emergence of cognitive changes in patients. Future studies should focus on additional risk factors for MCI subtypes and their possible progression to frank dementia.