A systematic review of neuropsychiatric symptoms in mild cognitive impairment

Mild cognitive impairment (MCI) is a clinical concept proposed as an intermediate state between normal aging anddementia. This condition has multiple heterogeneous sources, including clinical presentation, etiology, and prognosis. Recently,the prevalence and associated features of neuropsychiatric symptoms (NPS) in MCI have been described. We systematicallysearched the PubMed database (last accessed on August 31, 2008) for articles on NPS in MCI. Included articles used strictselection criteria, and outcome variables were extracted in duplicate; of the 27 articles included, 14 (52%) used prospectivecohorts. The global prevalence of NPS in MCI ranged from 35% to 85%. The most common behavioral symptoms weredepression, anxiety, and irritability. Hospital-based samples reported a higher global prevalence of NPS than population-basedstudies; this discrepancy probably reflected differences in demographics, study setting, MCI diagnostic criteria, and behavioralinstruments used. Prospective studies showed that NPS, particularly depression, may represent risk factors for MCI or predictorsfor the conversion of MCI to Alzheimer’s disease (AD). NPS are very prevalent in subjects with MCI, displaying a similar patternof symptoms compared to dementia and AD. Large cohort studies using standardized MCI criteria and behavioral instrumentsare required to evaluate the prognostic role of NPS in MCI