title: Apathy in Parkinson's disease: A systematic review and meta-analysis.
abstract: Apathy is a frequently reported neuropsychiatric symptom in Parkinson's disease (PD), but its prevalence and clinical correlates are debated. We aimed to address these issues by conducting a systematic review and meta-analysis. Embase, Medline/PubMed, and PsychINFO databases were searched for relevant studies. Data were extracted by two independent observers, using predefined extraction forms tailored specifically to the research question. From 1,702 titles and abstracts, 23 studies were selected. Meta-analysis showed a prevalence of apathy in PD of 39.8% (n = 5,388, 905% CI 34.6-45.0%). Apathy was associated with higher age (3.3 years, 95% CI = 1.7-4.9), lower mean Mini-Mental State Evaluation (MMSE) score (-1.4 points, 95% CI = -2.1 to -0.8), an increased risk of co-morbid depression (relative risk [RR] = 2.3, 95% CI = 1.9-2.8), higher Unified Parkinson's Disease Rating Scale (UPDRS) motor score (6.5 points, 95% CI = 2.6-10.3), and more severe disability (Hedges-G = 0.5, 95% CI = 0.3-0.6). Half of the patients with apathy had concomitant depression (57.2%, 95% CI = 49.4-64.9%), and this estimate was similar after exclusion of patients with cognitive impairment (52.5%, 95% CI = 42.2%-62.8%). In conclusion, we found that apathy affects almost 40% of patients with PD. Several factors influence reported prevalence rates, contributing to the considerable heterogeneity in study results. Half of patients with apathy do not suffer from concomitant depression or cognitive impairment, confirming its status as a separate clinical syndrome in PD. The pervasiveness of apathy in PD warrants research into its treatment, although different underlying pathophysiological mechanisms may require different treatment strategies. Treatment of apathy could improve patient quality of life, reduce caregiver burden, alleviate disability by increasing motivation for self-care, and reduce cognitive impairment by improving executive functioning.
authors: Department of Neurology, Academic Medical Center Amsterdam, The Netherlands.
authors: Melina G H E
authors: MG
authors: den Brok
authors: Department of Neurology, Academic Medical Center Amsterdam, The Netherlands.
authors: Jan Willem
authors: JW
authors: van Dalen
authors: Department of Neurology, Academic Medical Center Amsterdam, The Netherlands.
authors: Willem A
authors: WA
authors: van Gool
authors: Department of General Practise, Academic Medical Center Amsterdam, The Netherlands.
authors: Eric P
authors: EP
authors: Moll van Charante
authors: Department of Neurology, Academic Medical Center Amsterdam, The Netherlands.
authors: Rob M A
authors: RM
authors: de Bie
authors: Department of Neurology, Academic Medical Center Amsterdam, The Netherlands.|Department of Neurology, Radboud University Medical Center Nijmegen, The Netherlands.
authors: Edo
authors: E
authors: Richard
mesh_terms: D000367:Age Factors; D057565:Apathy; D003072:Cognition Disorders / Q000453:epidemiology* / Q000523:psychology; D015897:Comorbidity; D003863:Depression / Q000453:epidemiology* / Q000523:psychology; D006801:Humans; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000453:epidemiology / Q000503:physiopathology* / Q000523:psychology*; D015995:Prevalence; D011569:Psychiatric Status Rating Scales; D011788:Quality of Life / Q000523:psychology; D012307:Risk Factors
keywords: Parkinson's disease; apathy; behavior/neuropsychiatric disorders; epidemiology