Pathophysiology of vascular dementia and white matter changes.
Vascular dementia (VaD) can be defined as a dementia syndrome likely to be the consequence of lesions of the brain, vascular in origin, irrespective of their ischemic, hemorrhagic or hypoxic nature. Six subtypes (1) multi-infarct dementia, (2) strategic single infarct dementia, (3) small-vessel disease with dementia, (4) hypoperfusion dementia, (5) hemorrhagic dementia and other VaD, have been proposed, indicating the broad clinical spectrum of this disorder. Major determinants of the dementia syndrome are (i) stroke characteristics--i.e., lacunar infarcts, localization in the left hemisphere and/or in strategic regions--, (ii) white matter changes frequently seen in stroke patients, especially in those who have lacunes or deep hemorrhages, represent a strong predictor for risk of dementia--and (iii) associated Alzheimer pathology--Alzheimer and vascular lesions are frequently associated. Finally, it should also be considered the role of the summation of various lesion types, since many cases of dementia occurring in stroke patients are multifactorial.