Intellectual Disability and Mental Health Problems : Evaluation of Two Clinical Assessment Instruments, Occurrence of Mental Health Problems and Psychiatric Care Utilisation

Abstract: It has been suggested that persons with intellectual disabilities (ID) manifest the full range of mental health problems. The main purpose of this thesis is to adapt and evaluate two clinical assessment instruments and to investigate the occurrence of mental health problems as well as psychiatric care utilisation in persons with ID. The psychometric properties of a Swedish version of the two instruments [Reiss Screen for Maladaptive Behaviour (RSMB) and the Psychopathology Inventory for Mentally Retarded Adults (PIMRA)] were investigated in a random, institutional and clinical sample of administratively defined (ADDEF) adults with ID (n = 199). The analyses suggest that the RSMB could be used as intended by staff as a primary screening device for the identification of mental health problems in persons with ID, and that the PIMRA had a potential to identify individuals with a specific mental disorder. The psychometric evaluation reveals that the Swedish versions of the RSMB and PIMRA measure a construct related to the diagnostic categories in the DSM-III-R and DSM-IV. This construct could be conceptualised as mental health problems.The RSMB and PIMRA results show that the overall occurrence of mental health problems in ADDEF samples of persons with ID (175 men and 148 women) ranged from 34 to 64%.The preliminary level of ID was mild (23%), moderate (39%) and severe (38%). The most common mental health problems were aggressive and self-injurious behaviours, depression, anxiety and adjustment disorders. In registered patients receiving out- or in-patient psychiatric care the occurrence of adults with an ICD-10 diagnosis of ID was approximately 1% (70 to 90% had a mild level of ID). In contrast to the high frequency of mental health problems reported, psychiatric care was used infrequently. This tendency is particularly evident in persons with moderate and severe ID.