Longitudinal associations between mild behavioral impairment, sleep disturbance, and progression to dementia

ABSTRACT Background Clinical guidelines recommend incorporating non-cognitive markers like mild behavioral impairment (MBI) and sleep disturbance (SD) into dementia screening to improve detection. Objective We investigated the longitudinal associations between MBI, SD, and incident dementia. Methods Participant data were from the National Alzheimer’s Coordinating Center in the United States. MBI was derived from the Neuropsychiatric Inventory Questionnaire (NPI-Q) using a published algorithm. SD was determined using the NPI-Q nighttime behaviors item. Cox proportional hazard regressions with time-dependant variables for MBI, SD, and cognitive diagnosis were used to model associations between baseline 1) MBI and incident SD (n=11277); 2) SD and incident MBI (n=10535); 3) MBI with concurrent SD and incident dementia (n=13544); and 4) MBI without concurrent SD and incident dementia (n=11921). Models were adjusted for first-visit age, sex, education, cognitive diagnosis, race, and for multiple comparisons using the Benjamini-Hochberg method. Results The rate of developing SD was 3.1-fold higher in older adults with MBI at baseline compared to those without MBI (95%CI: 2.8-3.3). The rate of developing MBI was 1.5-fold higher in older adults with baseline SD than those without SD (95%CI: 1.3-1.8). The rate of developing dementia was 2.2-fold greater in older adults with both MBI and SD, as opposed to SD alone (95%CI:1.9-2.6). Conclusions There is a bidirectional relationship between MBI and SD. Older adults with SD develop dementia at higher rates when co-occurring with MBI. Future studies should explore the mechanisms underlying these relationships, and dementia screening may be improved by assessing for both MBI and SD.