Depression of AD: An Evidence-Based Epidemiological Systematic Review on Prevalence and Symptoms

OBJECTIVE: To compare prevalence rates of depression in AD by PDC-dAD and by other diagnostic and assessment approaches. BACKGROUND: The NIMH-Provisional diagnostic criteria for depression of AD (PDC-dAD) were developed specifically for the diagnosis of depression in Alzheimer9s Disease (AD). They differ from the DSM criteria for Major Depressive Disorder (MDD) because a) the severity of signs and symptoms of dAD is lower; b) it includes additional symptoms (irritability, social isolation and withdrawal); c) symptoms are phrased to avoid confounding with diminished language/cognitive abilities in AD. A decade after their inception there still is inconsistent use of assessment methods for studying depression in AD including the PDC-dAD, DSM, ICD and specific depression scales. Here we conduct an evidence-based examination of the prevalence estimates (PE) of depression in AD by PDC-dAD and other diagnostic approaches. DESIGN/METHODS: We performed a systematic search of the electronic literature and included all studies that report on the prevalence of depression of AD by PDC-dAD and at least by one other diagnostic or assessment approach. RESULTS: Five observational studies satisfied the inclusion criteria. PE by PDC-dAD ranged from 27.4 to 53.6% (median of 44%). PE by DSM-MDD ranged from 9.3 to 34.8% (median 14%). In 4 studies, the PE by ICD were 4.9 to 47.3% (median 32.4%). In 3 studies, the PE by the Neuropsychiatric Inventory (depression or dysphoria [NPI-Q] endorsed) ranged from 43.7% to 54% (median 50%). Other measures were inconsistently used and reported PE of 9.8 to 49.7%. CONCLUSIONS: The prevalence of depression in AD varies widely as a function of diagnostic approach, with higher prevalence rates associated with PDC-dAD than DSM or ICD. This raises important questions for future research about phenotype of depression in AD, particularly because neuropsychiatric symptoms are included in the McKhann 2011 NIA-AA diagnostic framework for all-cause dementia. Disclosure: Dr. Sepehry has nothing to disclose. Dr. Chen has nothing to disclose. Dr. Min has nothing to disclose. Dr. Hsiung has received research support from Baxter, Bristol-Myers Squibb Company, TauRx, Elan Corporation, GlaxoSmithKline, Inc., Novartis, Myriad, Ono Pharmaceutical, Pfizer Inc, and Sanofi-Aventis Pharmaceuticals, Inc. Dr. Beattie has nothing to disclose. Dr. Lee has received personal compensation for activities with Novartis and Pfizer. Dr. Jacova has nothing to disclose.