Mild cognitive impairment is associated with characteristic neuropsychiatric symptoms

Mild cognitive impairment (MCI) has emerged as an identifiable condition and in many cases is a transitional state preceding diagnosable Alzheimer disease (AD). Neurobiological and neuroimaging characteristics of amnestic-type MCI have been investigated, but few comprehensive neuropsychiatric studies have been reported. The aim of this preliminary study was to define the neuropsychiatric features of the amnestic-type MCI and compare them with those of mild AD and normal controls. The Neuropsychiatric Inventory (NPI) was used to assess the neuropsychiatric symptoms in three age and education comparable groups, i.e., 28 MCI, 124 mild AD, and 50 normal subjects. Individual subscores of the 10 NPI symptoms and total NPI scores were compared between the MCI patients and the other 2 groups. The results of this preliminary investigation showed that MCI patients frequently manifested neuropsychiatric symptoms. The most common symptoms in the MCI group were dysphoria (39%), apathy (39%), irritability (29%), and anxiety (25%). There were significant differences in apathy, dysphoria, irritability, anxiety, agitation, and aberrant motor behavior between the MCI and control groups; in contrast, only delusions were significantly less common in MCI compared with mild AD. There was a significant difference between the MCI and control groups on total NPI scores (p = 0.001), but not between the MCI and mild AD groups (p = 0.304). Amnestic MCI is associated with significant neuropsychiatric symptoms, especially mood disturbances and apathy. Psychotic symptoms are significantly more common in the early stage of AD than in MCI. These results are derived from a limited clinical sample and require confirmation in longitudinal community-based investigations.