Neuropsychiatric Disturbances in Mild Cognitive Impairment (MCI): A Systematic Review of Population-Based Studies

Mild cognitive impairment (MCI) is a nosological entity associated with a higher risk of developing dementia. Previous evidence indicates that behavioral and psychological symptoms of dementia (BPSDs) frequently occur in individuals of MCI. These neuropsychiatric manifestations may predict conversion to dementia. However, no updated systematic review has been conducted aiming to investigate the prevalence of BPSDs in MCI in general population samples. We conducted a systematic review to summarize research results regarding the prevalence of any or specific BPSDs in MCI subjects out of the clinical setting, compared to subjects who are either cognitively intact and/or demented. The PubMed/MEDLINE, EMBASE, and PsycInfo databases were searched from January 1st, 1990 to January 3rd, 2015 for general population studies in which the prevalence of BPSDs in individuals with MCI was estimated. Twenty-one studies met inclusion criteria. Studies varied in overall methodological quality as evaluated with a modified version of the New Castle-Ottawa Scale for cross-sectional studies. Depression (median prevalence: 29.8%; range: 6.8-63.3%), sleep disturbances (median prevalence: 18.3%; range: 7.9-49.0%), and apathy (median prevalence: 15.2%; range: 2.3-18.5%) were the more frequent BPSDs across studies. The prevalence range for any BPSD was 12.8-66.0%. No consistent pattern for differences in the prevalence of BPSDs according to MCI subtype emerged. Studies considered different diagnostic criteria for MCI and used different instruments to assess BPSDs in this population. In conclusion, BPSDs are prevalent among communitydwelling individuals with MCI. However, consistent socio-demographic and clinical correlates for BPSDs in this population remains to be established.