Cognitive Features of Vascular Dementia

A lot of studies have focused on cerebrovascular disease as an independent cause of dementia. In a study with consecutive stroke patients aged sixty and older, 26.3% of patients were demented three months after the stroke (Desmond et al., 2000). Within the demented patients, 57.1% had dementia directly related with stroke and 38.7% had dementia due to the combined effects of stroke and Alzheimer’s disease. Considering high prevalence of stroke, the prevalence of vascular dementia should be substantially high. Therefore early accurate diagnosis is crucial to the effective management of patients with vascular dementia. Recognizing a specific pattern of neuropsychological impairment could be a good diagnostic tool of vascular dementia. However, Cognitive features of vascular dementia are not homogenous because of various features, pathophysiology, and location of cerebrovascular diseases. Adopting the cognitive criteria of Alzheimer’s disease, which requires early prominent memory impairment, for use in vascular dementia could be erroneous in many cases of vascular dementia. Memory impairment has been an essential component of the operational criteria of dementia such as Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria (American Psychiatric Association, 1994) and even in National Institute of Neurological Disorders and Stroke and the Association Internationale pour La Recherche et l’Enseignement en Neuroscienes (NINDS-AIREN) criteria (McKhann G et al., 1994). On the other hand, in the Alzheimer’s Disease Diagnostic and Treatment Center (ADDTC) criteria (Chui et al., 1992) they do not require memory impairment as crucial element but need deterioration of intellectual function sufficient to interfere with customary affairs of life. Until now, many reports showed that frontal executive dysfunction is a prominent symptom of vascular dementia as well as less prominent memory impairment (Bowler et al., 1994, Tatemichi et al., 1992). It could be more appropriate omitting memory impairment as an essential component of the criteria of vascular dementia because of various locations of cerebrovascular lesion and of specified functional areas of human brain. In accordance with such ideas, impairment of two or more cognitive domains, not essentially include memory Impairment, was suggested as the diagnostic requirement of vascular dementia (Bowler & Hachinski, 2003). In this chapter we will focus on subcortical mild cognitive impairment and subcortical ischemic vascular dementia because of the relative homogeneity, higher prevalence (Roman et al., 2002; Erkinjuntti et al., 2000), and distinctive clinical features similar to Alzheimer’s disease.