The effects of age on rate of progression of Alzheimer disease and dementia with associated cerebrovascular disease

Background: Relatively little is known about how cerebrovascular disease af fects progression of dementia. Previous studies have found no differences i n progression of Alzheimer disease and vascular dementia, but these studies have not specifically examined age effects. Objective: To test whether the rate of cognitive decline is different in Al zheimer disease compared with dementia with associated cerebrovascular dise ase in clinical and autopsy patient series. Patients and Methods: We studied the longitudinal course of cognitive funct ion as measured by the Mini-Mental State Examination (MMSE) in patients wit h clinically and neuropathologically diagnosed conditions evaluated through a university Alzheimer disease center. Clinical patients were grouped acco rding to possible Alzheimer disease without stroke (n=37), probable Alzheim er disease without stroke (n=181), and dementia with stroke (n=50). Autopsy cases were categorized into Alzheimer disease (n=78) and dementia with vas cular disease (n=13). Data were analyzed using random-effects modeling of l ongitudinal change. Results: There was a significant interaction between age ZD and diagnosis i n determining rate of change on the MMSE scores for both the clinical and a utopsy samples. Rate of change decreased slightly with advancing age for Al zheimer disease groups, but increased with age for dementia with cerebrovas cular disease groups. Conclusions: Dementia with cerebrovascular disease declined faster in patie nts 80 years and older compared with Alzheimer disease without associated c erebrovascular pathological conditions, but showed slower decline in patien ts younger than 80 years. This effect most likely reflects combined Alzheim er and vascular pathological conditions in older patients with cerebrovascu lar disease.