Instruments for the detection of depressive symptoms in people with intellectual disabilities: a systematic review.

Affective disorders, particularly depression, are common in adults with intellectual disabilities. However the detection of these disorders is hindered by the varied presentation of depressive symptoms across the range of intellectual disability. We undertook a systematic review of the available English-language diagnostic instruments for depressive disorders for adults with all levels of intellectual disability. We appraised the studies based on the instruments' psychometric properties, sensitivity and specificity. We included 21 of 28 identified studies which contained original data on validity and reliability; the ;gold standard' ranged from clinical opinion to other established instruments, some of which had limited validation in people with intellectual disability. In view of the benefits of psychological treatments for common mental disorders, it is important to develop instruments to be used in monitoring cognitive as well as behavioural outcomes for people with intellectual disability and depressive disorders.