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Estimates of the risk of dementia in Parkinson's disease (PDD) vary widely. We aimed to review the incidence of PDD and in a meta‐analysis estimate the pooled annual incidence and relative risk of PDD while also exploring factors that may contribute to heterogeneity between studies. Preferred Reporting Items for Systematic reviews and Meta‐Analyses guidelines were followed and MEDLINE and EMBASE were searched for articles reporting the number of cases of dementia in a population, followed longitudinally, with a minimum of 100 dementia‐free Parkinson's disease (PD) patients at baseline. Meta‐analyses and meta‐regressions were used to estimate the pooled incidence rate of PDD and the relative risk of PDD versus healthy controls (HC). A total of 32 studies were identified, 25 reporting the incidence of PDD and 10 reporting the relative risk of PDD versus HC. The pooled incidence rate of PDD was 4.45 (95% confidence interval [CI], 3.91–4.99) per 100 person‐years at risk, equating to a 4.5% annual risk of dementia in a PD prevalent population. The relative risk of PDD was estimated to be 3.25 (95% CI, 2.62–4.03) times greater than HC. Factors contributing to study heterogeneity and disparities in the estimated risk of PDD include the age of patients, year of recruitment, and study location. Significant gaps remain with no studies identified in several geographical regions. Future studies should stratify by age and standardize reporting to reduce overall heterogeneity. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Treatments to slow the progression of cognitive dysfunction to dementia and improve the quality of life of persons with Parkinson's disease (PD) are desperately needed. Because PD mild cognitive impairment is considered a transitional stage before dementia, it opens a window to timely intervention. This article critically reviews the strengths and challenges of pharmacologic and nonpharmacologic clinical therapeutic trials in PD mild cognitive impairment conducted during the past 5 years, including ongoing trials. Relatively few high-quality trials have been conducted, and some important factors in designing future clinical trials are discussed. © 2018 International Parkinson and Movement Disorder Society.

Introduction: Alzheimer's disease pathologies are common in dementia with Lewy bodies, but their clinical relevance is not clear. CSF biomarkers amyloid beta 1-42, total tau, and tau phosphorylated at threonine 181 reflect Alzheimer's disease neuropathology antemortem. In PD, low CSF amyloid beta 1-42 predict long-term cognitive decline, but little is known about these biomarkers as predictors for cognitive decline in Lewy body dementia. The aim of this study was to assess whether Alzheimer's disease CSF biomarkers predict cognitive decline in Lewy body dementia.Methods: From a large European dementia with Lewy bodies multicenter study, we analyzed baseline Alzheimer's disease CSF biomarkers and serial MMSE (baseline and 1- and 2-year follow-up) in 100 patients with Lewy body dementia. Linear mixed-effects analyses, adjusted for sex, age, baseline MMSE, and education, were performed to model the association between CSF biomarkers and rate of cognitive decline measured with MMSE. An Alzheimer's disease CSF profile was defined as pathological amyloid beta 1-42 plus pathological total tau or phosphorylated tau.Results: The Alzheimer's disease CSF profile, and pathological levels of amyloid beta 1-42, were associated with a more rapid decline in MMSE (2.2 [P < 0.05] and 2.9 points difference [P < 0.01], respectively). Higher total tau values showed a trend toward association without statistical significance (2.0 points difference; P = 0.064), whereas phosphorylated tau was not associated with decline.Conclusions: Reduced levels of CSF amyloid beta 1-42 were associated with more rapid cognitive decline in Lewy body dementia patients. Future prospective studies should include larger samples, centralized CSF analyses, longer follow-up, and biomarker-pathology correlation. © 2016 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

This study was undertaken to determine the prevalence and correlates of cognitive impairment (CI) and neuropsychiatric symptoms (NPS) in early, untreated patients with Parkinson's disease (PD). Background Both CI and NPS are common in PD and impact disease course and quality of life. However, limited knowledge is available about cognitive abilities and NPS. Methods Parkinson's Progression Markers Initiative (PPMI) is a multi-site study of early, untreated PD patients and healthy controls (HCs), the latter with normal cognition. At baseline, participants were assessed with a neuropsychological battery and for symptoms of depression, anxiety, impulse control disorders (ICDs), psychosis, and apathy. Results Baseline data of 423 PD patients and 196 HCs yielded no between-group differences in demographic characteristics. Twenty-two percent of PD patients met the PD-recommended screening cutoff for CI on the Montral Cognitive Assessment (MoCA), but only 9% met detailed neuropsychological testing criteria for mild cognitive impairment (MCI)-level impairment. The PD patients were more depressed than HCs ( P < 0.001), with twice as many (14% vs. 7%) meeting criteria for clinically significant depressive symptoms. The PD patients also experienced more anxiety ( P < 0.001) and apathy ( P < 0.001) than HCs. Psychosis was uncommon in PD (3%), and no between-group difference was seen in ICD symptoms ( P = 0.51). Conclusions Approximately 10% of PD patients in the early, untreated disease state met traditional criteria of CI, which is a lower frequency compared with previous studies. Multiple dopaminergic-dependent NPS are also more common in these patients compared with the general population, but others associated with dopamine replacement therapy are not or are rare. Future analyses of this cohort will examine biological predictors and the course of CI and NPS. © 2015 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]