Prevalence and Impact of Medical Comorbidity in Alzheimer's Disease

Abstract

Background. We examined the prevalence of comorbid medical illnesses in Alzheimer's disease (AD) patients at different severity levels. We also examined the effect of cumulative medical comorbidity on cognition and function. Methods. Analyses of data from 679 AD patients (Mini-Mental State Exam score range 0–30, mean ± SD = 11.8 ± 8) from 13 sites (four dementia centers assessing outpatients, four managed care organizations, two assisted living facilities, and three nursing homes) prospectively recruited using a stratification approach including dementia severity and care setting. Medical comorbidity was quantified using the Cumulative Illness Rating Scale-Geriatric. Results. Across patients, 61% had three or more comorbid medical illnesses. Adjusting for age, gender, race, and care setting, medical comorbidity increased with dementia severity (mild to moderate, p < .01; moderate to severe, p < .001). Adjusting for age, educational level, gender, race, and care setting, higher medical comorbidity was associated with greater impairment in cognition (p < .001) and in self-care (p < .001). Conclusions. Despite the limitation of a cross-sectional design, our initial findings suggest that there is a strong association between medical comorbidity and cognitive status in AD. Optimal management of medical illnesses may offer potential to improve cognition in AD.