Neuropsychiatric symptoms in MCI subtypes: the importance of executive dysfunction

Abstract

Objective: Mild cognitive impairment (MCI) is a syndrome thought to be a prodrome of dementia for some patients. One subtype, amnestic MCI (aMCI), may be specifically predispose patients to develop Alzheimer's dementia (AD). Since dementia has been associated with a range of neuropsychiatric symptoms (NPS), we sought to examine the prevalence of NPS in MCI and its subtypes.

Methods: One thousand seven hundred seventy-nine participants in the National Alzheimer's Coordinating Center (NACC) with MCI were included in this study. All participants were evaluated systematically with a thorough cognitive battery, clinical interview, and consensus diagnoses, and subtyped as: (1) amnestic (aMCI) (single- or multiple-domain) versus non-amnestic (non-aMCI); (2) executive dysfunction-MCI (exMCI) (single- or multiple-domain) versus no executive dysfunction-MCI (non-exMCI); (3) both aMCI and exMCI; and (4) neither aMCI nor exMCI. Additionally, aMCI versus non-aMCI and exMCI versus non-exMCI dichotomies were explored. NPS were assessed with the Neuropsychiatric Inventory Questionnaire (NPI-Q) and Geriatric Depression Scale (GDS).

Results: 1379 participants (77.5%) met criteria for aMCI and 616 (34.6%) for exMCI. No differences were observed in the prevalence of NPS between aMCI versus non-aMCI. However, exMCI was associated with greater severity of depression, anxiety, agitation, disinhibition, irritability, and sleep problems, although these differences do not persist after adjustment for multiple comparisons.

Conclusions: While there were few associations between aMCI and NPS, the presence of executive dysfunction in MCI was associated with greater severity of symptoms and specifically with depression (evidenced by GDS score) and anxiety. These findings may have implications for MCI prognosis and need to be explored in longitudinal studies.