Factors affecting course and survival in Alzheimer's disease. A 9-year longitudinal study.

OBJECTIVE

To evaluate mean survival and to identify prognostic factors in a cohort of patients with Alzheimer's disease (AD).

DESIGN

Multicentric 9-year cohort analytic study.

SETTING

Seven neurology departments throughout Italy between April 1982 and January 1984.

PATIENTS

We recruited a consecutive sample of 145 patients affected by probable AD (Multicenter Italian Study on Dementia protocol, National Institute of Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria). Five were misdiagnosed, and 21 could not participate in the longitudinal study. The clinicodemographic characteristics of the 119 enrolled patients (49 men, 70 women; mean age, 64.7 years; SD, 4.1 years; mean duration of disease, 3.1 years; SD, 1.8 years) did not differ from those of the 26 excluded patients. All underwent extensive cliniconeuropsychological testing every 6 months for at least 2 years until the patient died or our survey ended (April 30, 1991). Mean follow-up was 5.1 years (SD, 2.5 years).

MAIN OUTCOME MEASURES

Death, severe functional impairment (a score > or = 17 on the Blessed Dementia Scale), and severe cognitive impairment (a score of < or = 7 on the Information-Memory-Concentration Test).

RESULTS

Survival curves obtained by the Kaplan-Meier method indicated that (1) patients with early- and late-onset disease (ie, before or after age 65 years) showed no difference either in relative survival or in time to reach predetermined functional and cognitive end points; (2) severely aphasic patients became profoundly demented significantly sooner than those with mild to moderate aphasia (P < .0001). Among clinicodemographic variables analyzed by a Cox model, severe language disability and functional loss proved to be the best predictors of death independent of age at onset or degree of dementia.

CONCLUSIONS

Age at onset did not influence course and survival in AD. Severe aphasia appears to be the best predictor of death and unfavorable course.