Neuropsychiatric Symptoms in Different Subtypes of Mild Cognitive Impairment

Abstract

Background: Mild cognitive impairment (MCI) is considered to be an intermediate cognitive state between the normal cognitive aging and dementia. Different MCI subtypes are classified by the number and characteristics of the affected cognitive domains. Neuropsychiatric symptoms (NPS) in dementia and MCI have been extensively studied, but little is known about its prevalence in MCI subtypes. In this study, we aimed to investigate NPS in different MCI subtypes. Methods: In this cross-sectional study, a total of 159 MCI subjects were recruited from the outpatient clinics of two hospitals in Taiwan from 2007-2011. All participants received baseline diagnostic evaluations, including medical history, physical examinations, neurologic and neuropsychological assessments. MCI patients were classified into different subtypes, including amnestic (aMCI), non-amnestic (non-aMCI), single-domain MCI, and multiple-domain MCI. The Neuropsychiatric Inventory was used to assess NPS. The prevalence and score of each neuropsychiatric symptom were compared between aMCI and non-aMCI, and between single-domain and multiple-domain MCI subtypes. Results: Of the 159 subjects with MCI, 99 (62.3%) met the criteria for aMCI, 60 (37.7%) for non-aMCI, 75 (47.2%) for single-domain MCI, and 84 (52.8%) for multiple-domain MCI. The non-aMCI group was associated with more prevalent anxiety and a higher anxiety score than the aMCI group. The difference became insignificant after controlling for age, sex, education and MMSE. When compared with the single-domain MCI group, the multiple-domain MCI group was more likely to have at least one NPS (63.1% vs. 45.3%, p=0.027), more prevalent apathy (26.2% vs. 13.3%, p=0.049), and a higher apathy score. After controlling for covariates, multiple-domainMCI group was still more likely to have at least one NPS (p=0.042). Conclusions: Our findings suggest that multiple-domain MCI is associated with more prevalent NPS than single-domain MCI. More studies are needed to determine the prevalence and pathophysiology of the NPS in different MCI subtypes.