Vascular dementia in a population-based autopsy study

Background: The validity of the clinical diagnosis of vascular dementia (VaD) remains suboptimal. Objective: To investigate clinicopathologic correlations in VaD. Methods: We used the medical records-linkage system of the Rochester Epidemiology Project to identify incident cases of dementia in Rochester, Minn, from January 1, 1985, through December 31, 1989. Dementia and Alzheimer disease (AD) were defined by the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Vascular dementia was defined by criteria including imaging results. Pathological characteristics of AD were quantified by means of standard scoring methods for neurofibrillary tangles and neuritic plaques. Vascular pathological findings were assessed by expert neuropathological opinion. Results: Of 419 patients with dementia who died before the study, neuropathological examination results were available in 89 (21%) with median age at onset of 80 years (range, 50-96 years; 52 [58%] women). Pathological diagnoses were AD in 45 patients (51%), pure VaD in 12 (13%), combined AD and VaD in 11 (12%), and other diagnoses in the remaining 21 patients. Criteria for VaD that required either a temporal relationship between a stroke and dementia onset or worsening, or bilateral infarctions in specified locations demonstrated on imaging results (Mayo Clinic criteria) had 75% sensitivity and 81% specificity for pure VaD (positive likelihood ratio, 3.9; 95% confidence interval, 2.2-6.7). Five cases of pure VaD lacked the temporal relationship and accounted for the imperfect sensitivity of the criteria. Conclusions: In this population-based autopsy study, the presence of vascular pathological characteristics in the absence of major AD pathological findings was common. Pure VaD without overt clinical strokes remains a challenge for antemortem diagnosis.