title: Prevalence of Depression in Patients With Mild Cognitive Impairment: A Systematic Review and Meta-analysis.
abstract: OBJECTIVE
  Depression is common in individuals with mild cognitive impairment (MCI) and may confer a higher likelihood of progression to dementia. Prevalence estimates of depression in those with MCI are required to guide both clinical decisions and public health policy, but published results are variable and lack precision.
  
  
  OBJECTIVE
  To provide a precise estimate of the prevalence of depression in individuals with MCI and identify reasons for heterogeneity in the reported results.
  
  
  METHODS
  A search of literature from database inception to March 2016 was performed using Medline, Embase, and PsycINFO. Hand searching of all included articles was performed, including a Google Scholar search of citations of included articles.
  
  
  METHODS
  Articles were included if they (1) were published in English, (2) reported patients with MCI as a primary study group, (3) reported depression or depressive symptoms using a validated instrument, and (4) reported the prevalence of depression in patients with MCI.
  
  
  METHODS
  All abstracts, full-text articles, and other sources were reviewed, with data extracted in duplicate. The overall prevalence of depression in patients with MCI was pooled using a random-effects model. Heterogeneity was explored using stratification and random-effects meta-regression.
  
  
  METHODS
  The prevalence of depression in patients with MCI, reported as a percentage with 95% CIs. Estimates were also stratified by population source (community-based or clinic-based sample), method of depression diagnosis (clinician-administered, informant-based, or self-report), and method of MCI diagnosis (cognitive vs global measure and amnestic vs nonamnestic).
  
  
  RESULTS
  Of 5687 unique abstracts, 255 were selected for full-text review, and 57 studies, representing 20 892 patients, met all inclusion criteria. The overall pooled prevalence of depression in patients with MCI was 32% (95% CI, 27-37), with significant heterogeneity between estimates (I2 = 90.7%). When stratified by source, the prevalence of depression in patients with MCI in community-based samples was 25% (95% CI, 19-30) and was 40% (95% CI, 32-48) in clinic-based samples, which was significantly different (P < .001). The method used to diagnose depression did not significantly influence the prevalence estimate, nor did the criteria used for MCI diagnosis or MCI subtype.
  
  
  CONCLUSIONS
  The prevalence of depression in patients with MCI is high. A contributor to heterogeneity in the reported literature is the source of the sample, with greater depression burden prevalent in clinic-based samples.
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Zahinoor
authors.initials: Z
authors.lastname: Ismail
authors.affiliation: Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Heba
authors.initials: H
authors.lastname: Elbayoumi
authors.affiliation: Keenan Research Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Corinne E
authors.initials: CE
authors.lastname: Fischer
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada4Division of Geriatric Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: David B
authors.initials: DB
authors.lastname: Hogan
authors.affiliation: Department of Clinical Health Psychology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Colleen P
authors.initials: CP
authors.lastname: Millikin
authors.affiliation: Keenan Research Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Schweizer
authors.affiliation: Centre for Research on Ageing, Health, and Wellbeing, Australian National University College of Medicine, Canberra, Australian Capital Territory, Australia.
authors.forename: Moyra E
authors.initials: ME
authors.lastname: Mortby
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Eric E
authors.initials: EE
authors.lastname: Smith
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada2Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Patten
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada2Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada7Department of Critical Care Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Kirsten M
authors.initials: KM
authors.lastname: Fiest
mesh_terms: D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D006801:Humans