title: 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.
authors.affiliation: Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27710, USA. dorai001@mc.duke.edu
authors.forename: P Murali
authors.initials: PM
authors.lastname: Doraiswamy
authors.forename: Joel
authors.initials: J
authors.lastname: Leon
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Cummings
authors.forename: Deborah
authors.initials: D
authors.lastname: Marin
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Neumann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000523:psychology; D003071:Cognition; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence