Vascular dementia (VaD) is a heterogeneous entity with a large clinicopathological spectrum. It has been classified and subclassified in many different ways. The difficulty in identifying the various subtypes is a problem in the diagnostic process. For clinical purposes, it is desirable to find subtypes of VaD that are homogeneous enough to allow meaningful comparisons across studies. This article presents candidates for such subtypes: poststroke dementia, subcortical VaD, and combined Alzheimer's disease and VaD (AD + VaD). The first two candidates are easy to identify. Poststroke dementia occurs with cognitive decline in close temporal relation to a transient ischemic attack. Subcortical VaD has a relatively homogeneous clinical picture for which detailed criteria are suggested. AD + VaD is more difficult to identify but is possible, sometimes with the aid of neuroimaging and/or biological markers.

Vascular dementia (VaD), like Alzheimer's disease (AD), is associated with cholinergic deficits. Rivastigmine provides sustained, brain-selective inhibition of acetylcholinesterase and butyrylcholinesterase. Preliminary data suggest that rivastigmine may provide significant benefits in patients with AD and cerebrovascular disease (mixed dementia), and in patients with VaD. Open-label rivastigmine treatment has been associated with improved cognitive and functional abilities, behavioral symptoms, and reduced caregiver stress in a small pilot study in these patients. Larger, prospective, double-blind studies of rivastigmine in patients with VaD are under way. These studies will confirm whether rivastigmine is an efficacious treatment option for a range of patients for whom, until now, there have been few symptomatic therapies.

“Mixed dementia” is traditionally defined as Alzheimer's disease with cerebrovascular disease (CVD). Because the risks of both neurodegenerative dementias and cerebrovascular disease increase with age, the mixed dementias are likely the most common. In practice, patients with mixed dementia are diagnosed by one of two routes: Either they have evidence of a neurodegenerative dementia and CVD at the outset, or, they have a classical neurodegenerative presentation but are found to have ischemic lesions by neuroimaging. These facts have implications for the development of evidence-based diagnostic criteria.