Four major clinical criteria are used in the diagnosis of VaD. The National Institute of Neurological Disorders and Stroke Association Internationale de Recherche et l'Ensignement en Neurosciences (NINDS-AIREN) criteria contain explicit statements about the diagnosis of dementia, the evidence for stroke, and the relationship between stroke and dementia (Román et al., 1993). Dementia, using this criteria, is defined as memory impairment and impairment in two other cognitive domains (i.e., language, attention, visuospatial skills, executive functioning). Cerebrovascular disease is defined by focal signs on neurological exam and evidence of stroke by brain imaging. Finally, there must be a relationship between the dementia and the vascular disease. The second clinical criteria in use are the California Alzheimer's Disease Diagnostic and Treatment Center (ADDTC) criteria for ischemic VaD (Chui et al., 1992). Dementia is defined as a deterioration from a prior level of functioning, and there must be evidence of two or more ischemic strokes. In comparing and contrasting these two clinical criteria, many differences are noted. The ADDTC group sought to clinically define only ischemic VaD, whereas the NINDS group sought to define all VaD. The ADDTC group defined dementia only as a deterioration of cognitive functioning, whereas the NINDS group defined dementia as memory impairment plus two other areas of cognitive impairment. The ADDTC group also required evidence of two ischemic strokes, whereas the NINDS group required evidence of only one stroke (ischemic or hemorrhagic).
The two other major criteria used to clinically define VaD include the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994), and Hachinski Ischemia Scale. The DSM-IV criteria define dementia as impairment in memory and in one other domain of cognitive functioning. Stroke is defined by focal signs and/or symptoms or by laboratory evidence. Unlike the ADDTC and the NINDS criteria, the DSM-IV criteria does not require evidence of stroke via brain imaging. The DSM-IV criteria for dementia are the same for vascular and AD memory impairment plus impairment in one other area of cognition. This differs from both the ADDTC and the NINDS.
The Hachinski Ischemia Scale was developed originally to differentiate vascular from Alzheimer's dementia (Hachinski, 1975). It uses a combination of history and signs and symptoms of vascular events. Speed of onset, presence of certain comorbid diseases, personality factors, and focal signs or symptoms make up the scale. The scale is now used to determine if there is a vascular component to the dementia rather than differentiating it from AD. The Hachinski Ischemia Scale is unique in its criteria relative to the other three.
Several studies have noted problems in clinical accuracy and reliability due to the preponderance of accepted clinical criteria for VaD. Wetterling, Kanitz, and Borgis (1996) noted that of 167 older demented patients, only 5 met the standards for 3 of the clinical criteria used to diagnose VaD. Forty-five of the patients met the DSM-IV criteria for VaD, 23 met the ADDTC criteria, and 12 met the NINDS criteria. Gold et al. (1997) studied the clinical utility of the NINDS and ADDTC using neuropathological data as the gold standard for diagnosis. The NINDS had a sensitivity of .58 and a specificity of .80, whereas the ADDTC had a sensitivity of .63 and a specificity of .64. A high percentage of cases had both AD and VaD.
In sum, Knopman et al. (2001) concluded from studies that compared various clinical criteria with neuropathological findings, that clinical diagnoses have high specificity but very low sensitivity.
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