The spectrum of cognitive disorders in Parkinson's disease: A data‐driven approach

Abstract

The objective of this study was to identify different cognitive phenotypes in Parkinson's disease (PD) using a data-driven approach. A model-based cluster analysis was conducted on the neuropsychological test results of 558 PD patients from 2 European movement disorder centers (Lille, n = 403; Maastricht, n = 155). The number of clusters was determined according to their clinical relevance as well as on the basis of 3 statistical criteria: the cubic cluster criterion, the pseudo F statistic, and the total squared correlation ratio (R(2)). A factorial discriminant analysis was performed to assess the quality of the cluster's separation. Descriptive variables were used to further characterize the clusters. A 5-cluster model was considered the clinically most relevant. The 5 clusters comprised: (1) cognitively intact patients (19.39%); (2) patients without cognitive deficits but with slight mental slowing (41.29%); (3) patients with slightly impaired overall cognitive efficiency and deficits in all cognitive domains except recognition memory (12.93%); (4) patients with severe mental slowing, impaired overall cognitive efficiency, and severe cognitive impairment in all domains, including memory (23.88%); and (5) patients with very severe impairment in all cognitive domains (2.51%). Cognitively intact patients were significantly younger and had received more years of formal education. Patients in the last 3 clusters had more severe motor symptoms, longer disease duration, and more axial signs. In the last cluster, most patients were demented. Our results confirm the heterogeneity of cognitive presentations in PD, ranging from cognitively intact patients with rather high levels of performance in each cognitive domain to very severely impaired patients.

Neuropsychological Subgroups in Non-Demented Parkinson’s Disease: A Latent Class Analysis

“…Research has suggested that executive-based deficits occur earlier in the disease course due to fronto-striatal dysfunction characteristic of PD, and memory deficits do not emerge until later in the disease course. [27] However, accumulating evidence suggests a subgroup of PD patients experience more posterior cortical dysfunction, which increases risk of dementia. In one longitudinal study examining predictors of dementia in PD, patients with deficits in measures of posterior cortical function were more predictive of dementia than measures of fronto-striatal function.…”

Response inhibition in Parkinson’s disease: a meta-analysis of dopaminergic medication and disease duration effects

“…Of the various cognitive deficits that patients with Parkinson’s disease (PD) experience (e.g., working memory, planning, and visuospatial attention), response inhibition is of particular importance for the recognition of its negative impact on quality of life. 1–4 Loss of response inhibition is associated with motor symptom severity 5 and freezing of gait, a particularly debilitating feature of the disease. 6–9 With a close link to broader clinical deficits and prediction of later dementia, 10 response inhibition performance has been posited as a sensitive outcome measure for diagnosis and progression of PD.…”

Genetic characterization of cognitive impairment in Parkinson's disease

“…Hence, early detection of cognitive impairment and identification of individuals at risk of dementia are major challenges. At present such classifications are usually based on clinical features that have limited prognostic value because of the heterogeneity of patients' cognitive profiles (Dujardin et al, 2013). In this issue of Brain, Nombela and colleagues perform a detailed characterization of cognitive impairment in Parkinson's disease (Nombela et al, 2014).…”