title: Late-life depression as a risk factor for mild cognitive impairment or Alzheimer's disease in 30 US Alzheimer's disease centers.
abstract: Identification of potentially modifiable risk factors for cognitive deterioration is important. We conducted a prospective study of 5,607 subjects with normal cognition and 2,500 subjects with mild cognitive impairment (MCI) at 30 Alzheimer's Disease Centers in the Unites States between 2005 and 2011. Cox regression was used to determine whether depression predicted transition from normal to MCI, or MCI to Alzheimer's disease (AD). Over an average of 3.3 visits, 15% of normal subjects transitioned to MCI (62/1000 per year), while 38% of MCI subjects transitioned to AD (146/1000 per year). At baseline, 22% of participants had recent (within the last two years) depression defined by clinician judgment; 9% and 17% were depressed using the Geriatric Depression Scale (GDS score ≥5) and the Neuropsychiatric Inventory Questionnaire (NPI-Q), respectively. At baseline, depressed subjects performed significantly worse on cognitive tests. Those always depressed throughout follow-up had an increased risk for progression from normal to MCI (RR = 2.35; 95% CI 1.93-3.08) versus never depressed. Normal subjects, identified as depressed at first visit but subsequently improved, were found to have lower risk of progression (RR 1.40 (1.01-1.95)). The 'always depressed' had only a modest increased risk of progression from MCI to AD (RR = 1.21 (1.00-1.46). Results were similar using time-dependent variables for depression or when defining depression via the GDS or NPI-Q. We found no effect of earlier depression (>2 years past). The effect of recent depression did not differ by antidepressant treatment, APOE4 allele status, or type of MCI. In conclusion, late-life depression is a strong risk factor for normal subjects progressing to MCI.
authors.affiliation: Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. nsteenl@emory.edu
authors.forename: Kyle
authors.initials: K
authors.lastname: Steenland
authors.forename: Conny
authors.initials: C
authors.lastname: Karnes
authors.forename: Ryan
authors.initials: R
authors.lastname: Seals
authors.forename: Claudine
authors.initials: C
authors.lastname: Carnevale
authors.forename: Adriana
authors.initials: A
authors.lastname: Hermida
authors.forename: Allan
authors.initials: A
authors.lastname: Levey
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D015331:Cohort Studies; D003863:Depression / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007253:Information Centers; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology