The incidence of post-mortem neurodegenerative and cerebrovascular pathology in mixed dementia.

Background: The clinical picture of dementia in most aged patients is due to a combination of different neurodegenerative processes and frequently associated to cerebrovascular lesions. They are called mixed dementia (MixD) cases, to be differentiated from those with pure vascular dementia (VaD) and those with Alzheimer's dementia (AD). The present study compares the frequency of different associated lesions in these disease groups.

Materials And Methods: Out of a series of 252 autopsied patients 36 with MixD, 20 with VaD and 64 with AD disease were compared concerning the frequency of the associated lesions. Small cerebrovascular lesions were evaluated on a large coronal section of a cerebral hemisphere. Mean values of frequency and severity were compared between the 3 groups.

Results: Of the 120 examined brains 30% were classified as MixD, 17% as VaD and 53% as AD. In 20% of the AD patients Lewy body pathology (LBP) was observed with a low incidence of cerebrovascular lesions, except for cerebral amyloid angiopathy (CAA). The MixD patients had more severe CAA and were significantly older than those with VaD and AD. Lacunar infarcts, on the other hand, were significantly more frequent in the VaD patients.

Discussion: The most responsible vascular lesions in MixD and VaD are different. There is an inverse correlation between the presence of LBP and vascular pathology. MixD has to be considered as the end stage of AD.