Validity of current clinical criteria for Alzheimer's disease, vascular dementia and dementia with Lewy bodies

BACKGROUND: Following the success of the NINCDS-ADRDA criteria for Alzheimer's disease, groups interested in vascular dementia and dementia with Lewy bodies have now adopted similar criteria. AIMS: To assess whether the validity of these criteria are influenced by the prevalence of mixed pathologies or by the prevalence rate. METHOD: A community based post-mortem study. RESULTS: Mixed pathologies were common (33.8%). The high specificities obtained for the CDLB and NINDS-AIREN criteria (1.00 and 0.95, respectively) were associated with low sensitivities (0.22 and 0.43, respectively). Low prevalence and the presence of mixed pathologies had a deleterious effect on positive predictive values. CONCLUSIONS: Current clinical diagnostic criteria are good at detecting pathology per se but not at detecting pure pathology. A large proportion of subjects from the general population fulfilling probable CDLB, probable NINCDS-ADRDA or probable NINDS-AIREN will have mixed pathologies.