Characterizing mild cognitive impairment in Parkinson's disease

Abstract

There is growing interest in identifying Parkinson's disease (PD) patients with mild cognitive impairment (PD-MCI), but widely disparate criteria have been used. We assessed 143 PD patients and 50 matched controls on 20 measures across 4 cognitive domains (executive function, attention and working memory, learning and memory, visuoperception). Twenty-four patients met criteria for dementia (PD-D); nondementia patients were classified as either with normal cognition or MCI for 12 neuropsychological criteria. We compared the influence of these criteria on the distribution of global cognitive performance in the resulting PD-MCI groups relative to the control and PD-D groups. Different criteria produced substantial variation in the proportion of PD-MCI cases identified. Fourteen percent PD-MCI was found when using 2 scores in 1 domain at 2 standard deviations (SD) below normative scores, with no controls identified as MCI, through to 89% PD-MCI with 1 score in 1 domain at 1 SD below normative scores, when 70% of controls were identified as MCI. The balance of cases with impaired cognition but not those with generally intact cognition was better served by using criteria that required 2 specific deficit scores or deficits across 2 domains. As comparisons with external normative data may have greater applicability across centers, we suggest that 2 scores at -1.5 SD within any single domain (30% PD-MCI) or 1 score at -1.5 SD in each of 2 domains (37% PD-MCI) provide suitable criteria to minimize the inclusion of cognitively well patients. Clinical dementia rating did not improve the relative identification of cognitively impaired and unimpaired nondementia PD patients.

Quality of Life and Mild Cognitive Impairment in Early Parkinson’s Disease: Does Subtype Matter?

“…Half of PD-MCI participants had attentional dysfunction, which was also the most common single-domain subtype. This has also been observed in a previous study [25] and has been shown to significantly impact physical functioning and social interaction [5]. Significantly, only 15% of PD-MCI subjects had single-domain impairment.…”

Emotion recognition impairment in Parkinson's disease patients without dementia

“…Following this recent guidelines [24] 23 (57.5%) of the 40 patients were classified as cognitively intact, although 13 of them exhibited impaired emotion recognition. Taking into consideration the whole group of patients, 26 of them had an emotion recognition deficit (see Fig.…”

Characterizing mild cognitive impairment in incident Parkinson disease

“…Subjects were further classified by domain if impaired in more than one test within that domain. In keeping with previous studies 6,21,22 and recent recommendations 23 and to reduce the risk of false-positive results caused by multiple testing, level 2 MCI at 1.5 SDs below normative means was used to compare laboratory and imaging data.…”