Mild cognitive impairment (MCI) reflects cognitive deficits without significant functional decline in activities of daily living. MCI subtypes are based on phenotypic patterns of impairment in cognitive domains (memory, attention, language, executive, visuospatial) as follows: Amnestic single domain (ASD) or multi-domain (AMD), Nonamestic single domain (NASD),  or multi-domain (NAMD). Previous studies have suggested Nonamnestic subtypes demonstrate more neuropsychiatric symptoms, but conclusions have been limited by small sample sizes. 

Using the National Alzheimer’s Coordinating Center (NACC) database (National Institute's of Aging grant U24 AG072122), we selected all initial Uniform Data Set assessments diagnosed as MCI with subtyping. The NACC data was collected from 37 participating Alzheimer’s Disease Research Centers. Baseline demographic and clinical features, Geriatric Depression Scale (GDS), and Neuropsychiatric Inventory (NPI-Q) were collected. Chi-square analyses were used to compare NPI-Q symptoms and severity across MCI subtypes.  

Participants: 9852 individuals with MCI were analyzed: 45.4% AMD, 33.7% ASD, 12.6% NASD, 8.2% NAMD. On NPI-Q, hallucinations, depression, anxiety, apathy, disinhibition, motor disturbances, nighttime behaviors, and appetite changes were significantly more common in Nonamnestic MCI compared to other subtypes (p<.001 for all domains except agitation and irritability [p<.05]). NPI-Q severity scores were significantly higher in Nonamnestic subtypes for depression, apathy, irritability and nighttime behaviors (all p<.01). NAMD was most frequent for all neuropsychiatric symptoms except irritability, wherein NASD had a higher prevalence. NAMD and NASD severity scores were equal for nighttime behaviors and irritability but with higher severity for apathy in NASD. GDS scores were highest in NAMD participants.

Nonamnestic MCI subtypes are characterized by greater frequency and severity of neuropsychiatric symptoms compared to Amnestic MCI subtypes.