title: Cognitive training in Parkinson disease: A systematic review and meta-analysis.
abstract: OBJECTIVE
  To quantify the effects of cognitive training (CT) on cognitive and behavioral outcome measures in patients with Parkinson disease (PD).
  
  
  METHODS
  We systematically searched 5 databases for randomized controlled trials (RCTs) of CT in patients with PD reporting cognitive or behavioral outcomes. Efficacy was measured as standardized mean difference (Hedges g) of post-training change.
  
  
  RESULTS
  Seven studies encompassing 272 patients with Hoehn & Yahr Stages 1-3 were included. The overall effect of CT over and above control conditions was small but statistically significant (7 studies: g = 0.23, 95% confidence interval [CI] 0.014-0.44, p = 0.037). True heterogeneity across studies was low (I(2) = 0%) and there was no evidence of publication bias. Larger effect sizes were noted on working memory (4 studies: g = 0.74, CI 0.32-1.17, p = 0.001), processing speed (4 studies: g = 0.31, CI 0.01-0.61, p = 0.04), and executive function (5 studies: g = 0.30, CI 0.01-0.58, p = 0.042), while effects on measures of global cognition (4 studies), memory (5 studies), visuospatial skills (4 studies), and depression (5 studies), as well as attention, quality of life, and instrumental activities of daily living (3 studies each), were not statistically significant. No adverse events were reported.
  
  
  CONCLUSIONS
  Though still small, the current body of RCT evidence indicates that CT is safe and modestly effective on cognition in patients with mild to moderate PD. Larger RCTs are necessary to examine the utility of CT for secondary prevention of cognitive decline in this population.
authors.affiliation: From the Regenerative Neuroscience Group (I.H.K.L., H.H., M.V., A.L.) and Parkinson's Disease Research Clinic (C.C.W., S.J.G.L.), Brain and Mind Centre, University of Sydney, Australia.
authors.forename: Isabella H K
authors.initials: IH
authors.lastname: Leung
authors.affiliation: From the Regenerative Neuroscience Group (I.H.K.L., H.H., M.V., A.L.) and Parkinson's Disease Research Clinic (C.C.W., S.J.G.L.), Brain and Mind Centre, University of Sydney, Australia.
authors.forename: Courtney C
authors.initials: CC
authors.lastname: Walton
authors.affiliation: From the Regenerative Neuroscience Group (I.H.K.L., H.H., M.V., A.L.) and Parkinson's Disease Research Clinic (C.C.W., S.J.G.L.), Brain and Mind Centre, University of Sydney, Australia.
authors.forename: Harry
authors.initials: H
authors.lastname: Hallock
authors.affiliation: From the Regenerative Neuroscience Group (I.H.K.L., H.H., M.V., A.L.) and Parkinson's Disease Research Clinic (C.C.W., S.J.G.L.), Brain and Mind Centre, University of Sydney, Australia.
authors.forename: Simon J G
authors.initials: SJ
authors.lastname: Lewis
authors.affiliation: From the Regenerative Neuroscience Group (I.H.K.L., H.H., M.V., A.L.) and Parkinson's Disease Research Clinic (C.C.W., S.J.G.L.), Brain and Mind Centre, University of Sydney, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Valenzuela
authors.affiliation: From the Regenerative Neuroscience Group (I.H.K.L., H.H., M.V., A.L.) and Parkinson's Disease Research Clinic (C.C.W., S.J.G.L.), Brain and Mind Centre, University of Sydney, Australia. amit.lampit@sydney.edu.au.
authors.forename: Amit
authors.initials: A
authors.lastname: Lampit
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology; D000368:Aged; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D016032:Randomized Controlled Trials as Topic / Q000379:methods