Vascular lesions in mixed dementia, vascular dementia, and Alzheimer disease with cerebrovascular disease: the Kurihara Project.

The concept and diagnosis for mixed dementia is not simple, since it is difficult to identify the type and regions of cerebrovascular disease (CVD) responsible for causing dementia. An investigation is needed to confirm the presence of mixed dementia, those who met the criteria for Alzheimer's disease (AD) and those for vascular dementia (VaD). According to the community-based stroke, dementia, and bed-confinement prevention in Kurihara, northern Japan (Kurihara Project), the prevalence of dementia and dementing diseases was surveyed in 2008-2010. Five hundred and ninety people finally agreed to participate (47.0%), and 73 (12.4%) people were diagnosed with dementia according to the DSM-IV. Using MRI, intensive evaluations on CVDs were performed for the 49 dementia patients associated with CVDs (mixed dementia, VaD, and AD with CVD). For the mixed dementia group, all had left subcortical strategic CVDs. These included the caudate head and thalamus. For the VaD group, all patients had at least cortical CVDs or subcortical strategic CVDs. The AD with CVD group had non-strategic CVDs in cortical, subcortical, or other areas in 5 or 6 patients each. Two extreme concepts regarding CVD and dementia are possible. One is that there is no concept for mixed dementia or VaD. An alternative is that the vascular factor should be considered as primary. Our data showed an importance of cortical and subcortical "strategic" areas, the latter included thalamus and caudate head.