The relationship of excess cognitive impairment in MCI and early Alzheimer's disease to the subsequent emergence of psychosis.
BACKGROUND
Psychotic symptoms in Alzheimer disease (AD + P) identify a heritable phenotype associated with greater cognitive impairment. Knowing when the cognitive course of AD + P subjects diverges from that of subjects without psychosis would enhance understanding of how genetic variation results in AD + P and its associated cognitive burden. This study seeks to determine whether the degree of cognitive impairment and cognitive decline in early AD predicts subsequent AD + P onset.


METHODS
361 subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis were evaluated every 6 months until psychosis onset.


RESULTS
Severity of cognitive dysfunction was a strong predictor of AD + P up to two years prior to psychosis onset. Cognition did not decline more rapidly prior to onset of AD + P.


CONCLUSIONS
Individuals who will develop AD + P already demonstrate excess cognitive impairment during the mild stages of disease. Genetic variation and brain pathophysiology may lead to a cognitive risk phenotype which is present prior to dementia onset.
Weamer
Elise A
EA
Department of Psychiatry, University of Pittsburgh, Pittsburgh, USA.
Emanuel
James E
JE
Varon
Daniel
D
Miyahara
Sachiko
S
Wilkosz
Patricia A
PA
Lopez
Oscar L
OL
Dekosky
Steven T
ST
Sweet
Robert A
RA
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010414:Pennsylvania; D010641:Phenotype; D011594:Psychometrics; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D012307:Risk Factors