ABSTRACT
BACKGROUND: It has been suggested that people with intellectual disabilities have a higher likelihood to develop psychiatric disorders, and that their treatment prognosis is relatively poor. AIMS: We aimed to establish the prevalence of intellectual disability in different mental healthcare settings, and estimate percentage of cognitive decline. We hypothesised that the prevalence of intellectual disabilities increases with intensity of care. METHOD: A cross-sectional study was conducted in different settings in a mental healthcare trust in the Netherlands. We used the Screener for Intelligence and Learning Disabilities (SCIL) to identify suspected mild intellectual disability (MID) or borderline intellectual functioning (BIF). We identified patients with a high level of education and low SCIL score to estimate which patients may have had cognitive decline. RESULTS: We included 1213 consecutive patients. Over all settings, 41.4% of participating patients were positive for MID/BIF and 20.2% were positive for MID only. Prevalence of suspected MID/BIF increased by setting, from 27.1% in out-patient settings to 41.9% in flexible assertive community treatment teams and admission wards, to 66.9% in long-stay wards. Only 85 (7.1%) of all patients were identified as possibly having cognitive decline. Of these, 25.9% were in long-stay wards and had a diagnosis of schizophrenia or substance use disorder. CONCLUSIONS: Low intellectual functioning is common in Dutch mental healthcare settings. Only a modest number of patients were identified as suffering from cognitive decline rather than suspected MID/BIF from birth. Therefore, we recommend improved screening of psychiatric patients for intellectual functioning at the start of treatment.
ABSTRACT
BACKGROUND: The reliability and validity of the Screener for Intelligence and Learning Disabilities (SCIL) are unknown in a population of outpatients with severe mental illness. The prevalence of mild or borderline intellectual disabilities (MBID); an umbrella term for people with borderline intellectual functioning (BIF) and mild intellectual disability (MID) in this population is also unknown. METHODS: A total of 625 patients were screened with the SCIL, 201 of which also had IQ test results. RESULTS: Cronbach's alpha of the SCIL was 0.73. The AUC value for detecting MBID was 0.81, and also 0.81 for detecting MID, with percentages of correctly classified subjects (when using the advised cut-off scores) being 73% and 79%, respectively. The SCIL results suggested that 40% of the patients were suspected of MBID and 20% of MID. CONCLUSION: The SCIL seems to be an appropriate screening tool for MBID. It is important to screen for MBID because a substantial proportion of outpatients with severe mental illness appear to be functioning at this level. It is necessary to adapt treatment for these patients.
