Evaluation of DSM-5 and IWG-2 criteria for the diagnosis of Alzheimer’s disease and dementia with Lewy bodies

Abstract

Abstract Despite differing target audiences and scope it is possible to compare the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) [American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 5th ed. Arlington: American Psychiatric Association, 2013] and the Second International Working Group for New Research Criteria for the Diagnosis of Alzheimer’s Disease (IWG-2) [Dubois B, Feldman HH, Jacova C, Hampel H, Molinuevo JL, Blennow K, et al. Advancing research diagnostic criteria for Alzheimer’s disease: the IWG-2 criteria. Lancet Neurol 2014;13:614–29] diagnostic criteria for both Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB). With regard to the diagnosis of AD the principal difference is the inclusion of biomarkers in the IWG-2 diagnostic criteria for this condition. This creates a number of difficulties including a lack of regulatory approval, cultural and other objections to the collection of cerebrospinal fluid (CSF), and a lack of facilities for collection and analysis restricting analysis of CSF proteins to larger tertiary centres [Dubois B, Feldman HH, Jacova C, Hampel H, Molinuevo JL, Blennow K, et al. Advancing research diagnostic criteria for Alzheimer’s disease: the IWG-2 criteria. Lancet Neurol 2014;13:614–29]. With regard to diagnostic criteria for DLB, IWG-2 research criteria designate the co-occurrence of AD and DLB as ‘mixed AD’. However, Alzheimer’s type pathology (ADTP) and Lewy body pathology frequently occur together rendering a separate ‘mixed AD’ category superfluous. The reality is that routine clinical diagnosis of AD and DLB will continue to be based on a thorough general and neurological examination indicating a preponderance of signs and symptoms for one or other of these conditions [Seeley WW, Miller BL. Alzheimer’s disease and other dementias. In: Hauser SL, Josephson SA, editors. Harrison’s neurology in clinical medicine, 3rd ed. New York: McGraw Hill, 2013]. Similarly, AD and DLB research will continue to primarily depend on clinically focussed DSM-5 criteria, making DSM-5 superior to IWG-2 in both clinical and research settings.