An initial study of modifiable and non-modifiable factors for late-life psychosis.

OBJECTIVE

To determine rates of psychotic symptoms and associated modifiable and non-modifiable factors among elderly long term nursing home residents without prior history of psychiatric illness.

METHOD

A cross-sectional design using the Scale for the Assessment of Positive Symptoms (SAPS) to measure psychotic symptoms, the Folstein's Mini-Mental State Exam (MMSE), and Mattis Dementia Rating Scale (DRS) to evaluate cognitive impairment. Frequency and rates of global psychotic symptoms and hallucinations, delusions, formal thought disorder, and bizarre behavior were calculated. Logistic regression was used to examine modifiable (e.g., medication use) and non-modifiable clinical characteristics (e.g., older age) associated with late-life psychosis.

RESULTS

There were 15.9% of subjects reporting delusions and 7.3% reporting hallucinations. History of stroke, poorer cognition, and receiving multiple medications showed significant association with late-life psychosis. Only stroke (OR = 9.12; 95% CI: 1.58-52.74) and receiving different classes of medications (benzodiazepines, neuroleptics, and antidepressants) (OR = 13.17; 95% CI: 2.10-85.82) remained significantly associated with psychosis after adjusting for Mattis DRS total score. Further analyses excluding subjects with MMSE scores of 24 or lower (n = 24) showed essentially the same results but subjects with better cognitive function suffered a less severe form of psychosis, essentially constituted by one symptom type (i.e., visual hallucinations).

CONCLUSIONS

Rates of late-life psychosis in this sample of nursing home residents without previous psychiatric history were high. Simultaneous use of medications including antidepressants, sedatives, and stimulants may be a clinically relevant modifiable factor to be targeted in prevention studies. Severity and type of psychosis is dependent on the severity of cognitive impairment.