A review of screening tests for cognitive impairment.

The merit of screening for dementia and cognitive impairment has been the subject of recent debate. One of the main limitations in this regard is the lack of robust evidence to support the many screening tests available. Although plentiful in number, few such instruments have been well validated in the populations for which they are intended to be used. In addition, it is likely that "one size does not fit all" in cognitive screening, leading to the development of many specialised tests for particular types of impairment. In this review, we sought to ascertain the number of screening tools currently available, and to examine the evidence for their validity in detecting different diagnoses in a variety of populations. A further consideration was whether each screen elicited indices of a range of cognitive, affective and functional domains or abilities, as such information is a valuable adjunct to simple cut-off scores. Thirty-nine screens were identified and discussed with reference to three purposes: brief assessment in the doctor's office; large scale community screening programmes; and identifying profiles of impairment across different cognitive, psychiatric and functional domains/abilities, to guide differential diagnosis and further assessment. A small number of screens rated highly for both validity and content. This review is intended to serve as an evaluative resource, to guide clinicians and researchers in choosing among the wide range of screens which are currently available.