Abstract
•Intellectual disability is associated with increased risk of behavioral disturbances.•There is little data about detection of intellectual disability in psychiatric cases.•Out of 2621consecutive testing referrals, 16% had Full Scale IQs below 70.•Of the cases referred for formal assessment of 81% had composite scores below 70.•These data suggest a high rate of undetected intellectual disability.
Intellectual disability is associated with an increased risk of behavioral disturbances and also complicates their treatment. Despite increases in the sophistication of medical detection of early risk for intellectual disability, there is remarkably little data about the detection of intellectual disability in cases referred for psychiatric treatment. In this study, we used a 10-year sample of 23,629 consecutive child and adolescent admissions (ages between 6 and 17) to inpatient psychiatric treatment. Eleven percent (n=2621) of these cases were referred for psychological assessment and were examined with a general measure of intellectual functioning (i.e., WISC-IV). Of these cases, 16% had Full Scale IQs below 70. Of the cases whose therapists then referred them for formal assessment of their adaptive functioning (i.e., ABAS-II) 81% were found to have composite scores below 70 as well. Only one of the cases whose Full Scale IQ was less than 70 had a referral diagnosis of intellectual disability. Cases with previously undetected intellectual disability were found to be significantly more likely to have a diagnosis of a psychotic disorder and less likely to have a diagnosis of mood disorder than cases with IQs over 70. Disruptive behavior disorder diagnoses did not differ as a function of intellectual performance. These data suggest a high rate of undetected intellectual disability in cases with a psychiatric condition serious enough to require hospitalization and this raises the possibility that many such cases may be misdiagnosed, the basis of their problems may be misconceptualized, and they may be receiving treatments that do not take into account their intellectual level.
