Advances in Vascular Cognitive Impairment 2005

Diagnosis of vascular cognitive impairment (VCI) or vascular dementia (VaD) is highly dependent on operational definitions. Among 480 cases of incident dementia in the Cardiovascular Health Study (CHS) Cognition Study, Lopez et al1 demonstrated how findings from brain imaging and choice of diagnostic criteria influence the classification of VaD. As shown by previous investigators, the number of cases classified as VaD increases with the availability of imaging. Furthermore, the widely-used NINDS-AIREN criteria (42 probable VaD) are more conservative than the DMS IV (62 VaD) or California ADDTC criteria (117 probable VaD). In the CHS cohort, several baseline MRI findings (in addition to history of stroke) were identified as risk factors for incident VaD: white matter hyperintensities (WMH), number of MRI infarcts, and ventricular size.2 Increased incidence of Alzheimer disease (AD) was also increased by the severity of coronary and peripheral atherosclerosis.3 Thus, MRI or systemic measures of CVD may offer important surrogate markers for VCI. VaD is purported to be more common than AD in Asia. In a study of 34 807 persons, aged 65 or older, living in several Chinese communities, Zhang et al4 reported a prevalence of 4.8% for AD and 1.1% for VaD. These results suggest that the prevalence of dementia subtypes in China is similar to Western countries. It should be noted, however, that the application of NINDS-AIREN criteria and the absence of brain imaging may underestimate the extent of underlying CVD. Costs related to VCI for society and individuals have been examined. According to 2 studies5,6 annual utilization of health care resources and primary caregivers are higher for VaD than AD. In the CHS cohort,7 median survival from dementia onset to death was shorter in VaD (3.9 year) than in AD (7.1 years) and cognitively normal controls (11.0 years). This is not surprising, because VaD would be associated with higher cardiovascular mortality. The role of inflammation, infection, and antioxidants have been explored. In the Rotterdam Study8 levels of fibrinogen, but not C-reactive protein, were associated with an increased risk of AD and VaD. In a Japanese case-control study,9 antibodies against Chlamydia pneumoniae were found more often in VaD than in AD. In the Canadian Study of Health and Aging,10 subjects reporting any antioxidant vitamin–use at baseline showed a significantly lower risk for incident VCI, but not dementia or AD. These data are intriguing but preliminary.