Cognitive impairment in the non-elderly: Validation of a new tool to assess intellectual disability in community and clinical populations

In the absence of dementia or delirium, cognitive impairment in non-elderly adults is most often associated with intellectual or developmental disability. There is limited information about the prevalence of intellectual disability or its impact on mental disorders and health services use derived from epidemiological studies. Existing assessment measures of intelligence are not easily administered in large, population samples. This study investigates cognitive impairment in the non-elderly utilizing data from the NIMH Epidemiologic Catchment Area Program (ECA). The study also examines the validity and psychometric properties of a newly-developed, brief, and easily administered instrument to assess cognitive impairment in non-elderly adults in community and clinical populations. Utilizing items of the ECA Standardized Psychiatric Examination encompassing three domains-proverb interpretation, fund of knowledge, and interpretation of similarities and differences-a scale (PROFOKS) was developed and validated against various measures and indicators of cognitive impairment in both the community and clinical samples.