Comparison of instruments for the diagnosis of dementia in individuals with intellectual disability

This article describes the agreement among the results (dementia/no dementia) of three instruments used for the potential diagnosis of dementia in persons with intellectual disability. The instruments are: the Dementia Questionnaire for Mentally Retarded Persons (DMR), the Checklist with Symptoms of Dementia (CLD) and the Delayed Match-to-Sample Test (DMTS). The results were compared with the expert opinion of a physician/educational specialist/psychologist. The participants were 329 adults affiliated with centres for people with intellectual disability in The Netherlands. It was found that the agreement among the three instruments was low (kappa <0.5). The agreement between the expert opinion and the results of the tests was also found to be low. It was concluded that the instruments do not mutually agree upon which of the adults can be regarded as dementing or not dementing and they also provide inconsistent agreement with the expert opinion when dementia is present. It was further concluded that it is not advisable to use a single instrument when attempting to diagnose dementia in people with intellectual disability.