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. Declaration of interest Supported by the Medical Research Council (UK) and by a project grant from the Wellcome Trust.