Heterogeneity in Alzheimer’s/Vascular Spectrum Dementia

Alzheimer’s disease (AD) and vascular dementia (VaD) are considered to be the two most common types of dementia with each of these dementia syndromes believed to represent more or less independent entities. While mixed dementia syndromes are acknowledged, the prevailing point of view continues to suggest that AD and VaD represent disorders with different underlying etiology. This chapter will review some of the recent neuropathological and neuropsychological literature suggesting considerable heterogeneity between AD and VaD. It is our contention that the literature reviewed in this chapter supports the notion that neuropsychological syndromes seen in AD/VaD dementia, in addition to their underlying biological substrate, are best understood as existing along a clinical/pathological continuum or spectrum. This heterogeneity should be leveraged to construct a more sophisticated and heuristically meaningful way to classify patients with dementia.