Misidentification Subtype of Alzheimer's Disease Psychosis Predicts a Faster Cognitive Decline

The presence of psychosis is associated with a more rapid decline in Alzheimer's disease (AD), but the impact of paranoid (persecutory delusions) and misidentification (misperceptions and/or hallucinations) subtypes of psychosis on the speed of decline in AD is still unclear. We analyzed data on Alzheimer's Disease Neuroimaging Initiative 2 participants with late mild cognitive impairment or AD, and we described individual trajectories of Alzheimer's Disease Assessment Scale-Cognitive Subscale scores using a semimechanistic logistic model with a mixed effects-based approach, which accounted for dropout and adjusted for baseline Mini Mental State Examination scores. The covariate model included psychosis subtypes, age, gender, education, medications, and Apolipoprotein E epsilon 4 (Apo-e ε4 genotype). We found that the Alzheimer's Disease Assessment Scale-Cognitive Subscale rate of increase was doubled in misidentification (β_{r,misid_subtype}  = 0.63, P = 0.031) and mixed (both subtypes; β_{r,mixed_subtype}  = 0.70, P = 0.003) when compared with nonpsychotic (or paranoid) patients, suggesting that the misidentification subtype may represent a distinct AD sub-phenotype associated with an accelerated pathological process.