Relationship between behavioural and psychological symptoms of dementia and cognition in Alzheimer's disease.
BACKGROUND
Behavioural and psychological symptoms of dementia (BPSDs) are common. It is unclear whether associations are stronger with the absolute cognitive level or that relative to premorbid mental ability.


METHODS
The Neuropsychiatric Inventory (NPI) was administered to carers of patients with Alzheimer's disease (AD). Patients underwent cognitive testing with the National Adult Reading Test (NART) to estimate premorbid IQ and 6 tests of current cognitive function.


RESULTS
556 patients, mean age 77.3 years, had NPI scores. The total NPI score correlated significantly with most cognitive test scores, but multi-linear regression identified NART-IQ as the only significant cognitive predictor (beta=-0.17, p=0.008). Principal component analysis of the 10 NPI domains extracted 3 components corresponding to mood, frontal and psychotic factors. The NPI mood factor correlated significantly with NART-IQ (rho=-0.14, p=0.014) and lexical verbal fluency (rho=-0.09, p=0.034) only. The NPI frontal factor correlation with NART-IQ approached significance (rho=-0.11, p=0.053). The NPI psychotic factor correlated significantly with the Mini-Mental State Examination (rho=-0.15, p<0.001) and the Hopkins verbal learning test (rho=-0.11, p=0.013) scores.


CONCLUSIONS
The relationship between BPSDs and cognition in AD is weak and largely explained by premorbid IQ. There is a stronger relationship between current cognition and psychotic symptoms.
Starr
John M
JM
Geriatric Medicine Unit, Royal Victoria Hospital, Edinburgh, UK. John.Starr@ed.ac.uk
Lonie
Jane
J
D000339:Affect; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000523:psychology*; D001526:Behavioral Symptoms / Q000150:complications / Q000175:diagnosis*; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis*; D003704:Dementia / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D025341:Principal Component Analysis; D011618:Psychotic Disorders / Q000150:complications