Population-based study of medical comorbidity in early dementia and "cognitive impairment, no dementia (CIND)": association with functional and cognitive impairment: The Cache County Study.

OBJECTIVE: Authors investigated medical comorbidity in persons with dementia and "Cognitive Impairment, No Dementia" (CIND).
METHODS: The Cache County Study is an ongoing population-based study of the epidemiology of dementia, the risk factors for conversion from CIND to dementia, and the progression of dementia. As part of the study's first incidence wave, persons with dementia (N=149), CIND (N=225), or without cognitive impairment (N=321) were identified and studied. Participants received comprehensive clinical evaluations and were rated on the General Medical Health Rating (GMHR), a global measure of seriousness of medical comorbidity. Participants and informants also completed the Mini-Mental State Exam and provided self-report information about comorbid medical conditions and functioning in activities of daily living.
RESULTS: There were few differences in number or type of comorbid medical conditions between persons with CIND and dementia, but persons with dementia were prescribed more medications. Stroke was more common in dementia participants, but other illnesses common in old age were not significantly different across cognitive groups. Medical comorbidity was more serious in both dementia and CIND, such that both groups were less likely to have "little to no" comorbidity. Seriousness of medical comorbidity was significantly associated with worse day-to-day functioning and cognition.
CONCLUSIONS: Persons with CIND and dementia have more serious medical comorbidity than comparable persons without cognitive impairment. This comorbidity may play a role in the progression of CIND and dementia. Future studies should investigate the role of medical comorbidity and its treatment on dementia onset or progression, as well as the mechanisms mediating its neuropathologic effects.