An exploration of subgroups of mild cognitive impairment based on cognitive, neuropsychiatric and functional features: analysis of data from the National Alzheimer's Coordinating Center.

OBJECTIVES: To empirically expand the existing subtypes of mild cognitive impairment (MCI) by incorporating information on neuropsychiatric and functional features, and to assess whether cerebrovascular disease (CVD) risk factors are associated with any of these subgroups.
DESIGN: Latent class analysis using 1,655 patients with MCI.
SETTING: Participants in the Uniform Data Set (UDS) from 29 National Institutes of Health-supported Alzheimer's Disease Centers. PARTICIPANTS: Patients with a consensus diagnosis of MCI from each center and with a Mini-Mental State Examination score of 22 or greater. MEASUREMENTS: UDS cognitive battery, Neuropsychiatric Inventory Questionnaire, and Functional Assessment Questionnaire administered at initial visit.
RESULTS: Seven empirically based subgroups of MCI were identified: 1) minimally impaired (relative frequency, 12%); 2) amnestic only (16%); 3) amnestic with functional and neuropsychiatric features (16%); 4) amnestic multidomain (12%); 5) amnestic multidomain with functional and neuropsychiatric features (12%); 6) functional and neuropsychiatric features (15%); and 7) executive function and language impairments (18%). Two of these subgroups with functional and neuropsychiatric features were at least 3.8 times more likely than the minimally impaired subgroup to have a Rosen-Hachinski score of 4 or greater, an indicator of probable CVD.
CONCLUSIONS: Findings suggest that there are several distinct phenotypes of MCI characterized by prominent cognitive features, prominent functional features, and neuropsychiatric features or a combination of all three. Subgroups with functional and neuropsychiatric features are significantly more likely to have CVD, which suggests that there may be distinct differences in disease etiology from the other phenotypes.