Incidence of Mild Cognitive Impairment and Dementia in Parkinson’s Disease: The Parkinson’s Disease Cognitive Impairment Study

Abstract

Background: Cognitive impairment in Parkinson’s disease (PD) includes a spectrum varying from Mild Cognitive Impairment (PD-MCI) to PD Dementia (PDD). The main aim of the present study is to evaluate the incidence of PD-MCI, its rate of progression to dementia, and to identify demographic and clinical characteristics which predict cognitive impairment in PD patients.Methods: PD patients from a large hospital-based cohort who underwent at least two comprehensive neuropsychological evaluations were retrospectively enrolled in the study. PD-MCI and PDD were diagnosed according to the Movement Disorder Society criteria. Incidence rates of PD-MCI and PDD were estimated. Clinical and demographic factors predicting PD-MCI and dementia were evaluated using Cox proportional hazard model.Results: Out of 139 enrolled PD patients, 84 were classified with normal cognition (PD-NC), while 55 (39.6%) fulfilled the diagnosis of PD-MCI at baseline. At follow-up (mean follow-up 23.5 ± 10.3 months) 28 (33.3%) of the 84 PD-NC at baseline developed MCI and 4 (4.8%) converted to PDD. The incidence rate of PD-MCI was 184.0/1000 pyar (95% CI 124.7–262.3). At multivariate analysis a negative association between education and MCI development at follow-up was observed (HR 0.37, 95% CI 0.15–0.89; p = 0.03). The incidence rate of dementia was 24.3/1000 pyar (95% CI 7.7–58.5). Out of 55 PD-MCI patients at baseline, 14 (25.4%) converted to PDD, giving an incidence rate of 123.5/1000 pyar (95% CI 70.3–202.2). A five time increased risk of PDD was found in PD patients with MCI at baseline (RR 5.09, 95% CI 1.60–21.4).Conclusion: Our study supports the relevant role of PD-MCI in predicting PDD and underlines the importance of education in reducing the risk of cognitive impairment.

Prevalence and Clinical Aspects of Mild Cognitive Impairment in Parkinson's Disease: A Meta‐Analysis

“…A total of 9 of 25 studies found that patients with PD‐MCI took higher LEDD than patients without PD‐MCI; our meta‐analysis confirmed this association (Supplementary Material 5; Table ), with a significant and positive ES (= 0.25). The heterogeneity among the studies was significant and moderate, but sensitivity analysis indicated stability of ES level, and there was no publication bias.…”

“…Of 21 studies, 8 revealed that PD‐MCI patients had higher H&Y stages than patients without PD‐MCI (Supplementary Material 5). Our meta‐analytic study showed that PD‐MCI patients had higher scores on the H&Y (Table ), with a significant and positive ES (= 0.33).…”

“…The relation of PD‐MCI with TD and PIGD motor subtypes were assessed in 5 studies (Supplementary Material 3). Our meta‐analysis revealed that the prevalence of PD‐MCI was higher in the PIGD subtype (46%; n = 587; 95% CI = 41–51; Q = 4.80; P = 0.309; I 2 = 16.63%) when compared with the TD subtype (35%; n = 357; 95% CI = 30–40; Q = 3.27; P = 0.513; I 2 = 0%).…”

“…evaluated the results and resolved any disagreement by discussion or with recourse to a third arbitrator (L.T.). A primary study was included in the meta‐analysis if it (1) was published in peer‐reviewed journals in English; (2) was published from 2012 (year of publication of the MDS clinical criteria for diagnosis of PD‐MCI) to 2019; (3) provided a prevalence rate for PD‐MCI; (4) provided statistical results (ie, mean, standard deviation, standard difference) about comparisons on demographic, clinical, and neuropsychiatric measures between PD patients with or without PD‐MCI; (5) samples were independent (for the prospective study we used baseline data), and (6) PD‐MCI was diagnosed according to specific diagnostic criteria (PD‐MCI group of each primary study did not include PD‐D patients because “fulfilment of MDS criteria for PD‐D is an exclusion criterion” for a clinical diagnosis of PD‐MCI). We excluded primary studies with less than 50 participants, conference proceedings, letters to the editor, commentaries, theses, studies performed on animals, and single‐case studies.…”

“…Mild cognitive impairment associated with Parkinson's disease (PD‐MCI) is a risk factor for the development of dementia associated with PD; thus, the early identification of patients with PD‐MCI in clinical routine might allow to deploy appropriate pharmacological and nonpharmacological interventions (ie, cognitive training). Until now, several prospective and cross‐sectional studies provided mixed data on the prevalence rate of PD‐MCI, ranging from about 20% to 70% . Inconsistencies across studies can be partly explained by several methodological factors, such as the heterogeneity in diagnostic criteria for MCI, patient samples, neuropsychological batteries, and different levels of diagnosis (ie, Abbreviated Assessment, Level I or Comprehensive Assessment, Level II, according to the Movement Disorder Society [MDS]).…”