Incidence of vascular dementia in Rochester, Minn, 1985-1989

To examine the contribution of cerebrovascular disease to dementia.

We used the records-linkage system of the Rochester Epidemiology Project to ascertain incident cases of dementia in Rochester, Minn, for 1985 through 1989. We defined dementia using the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. To define dementia types, we reviewed neuroimaging reports, which were available for two thirds of dementia cases, in addition to medical histories and neurologic examination results. Vascular dementia (VaD) was defined by 1 of the following criteria: dementia onset or worsening within 3 months of a clinical stroke or bilateral gray matter infarctlike lesions shown by imaging that fulfilled specified location criteria (critical imaging lesions).

We found 482 incident cases of dementia. Overall, 10% of patients had onset or worsening of their dementia within 3 months of a stroke. Eleven percent of the incident dementia cases had bilateral gray matter lesions on imaging that were considered critical. Eighteen percent of patients had one or the other of these features (VaD by our criteria), but only 4% of patients had both. The incidence rate of VaD increased steeply with advancing age and was similar in men and women. Our incidence rates were similar to those from a recent European meta-analysis.

The presence of either a stroke temporally related to dementia onset or worsening or of critical imaging lesions was common among dementia patients, whereas the occurrence of both features together was rare.