Psychosis and adults with intellectual disabilities
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To determine the point prevalence, incidence, and remission over a 2-year period of psychosis in adults with intellectual disabilities, and to investigate demographic and clinical factors hypothesised to be associated with psychosis.
A population-based cohort of adults with intellectual disabilities (n = 1,023) was longitudinally studied. Comprehensive face-to-face mental health assessments to detect psychosis, plus review of family physician, psychiatric, and psychology case notes were undertaken at two time points, 2 years apart.
Point prevalence is 2.6% (95% CI = 1.8–3.8%) to 4.4% (95% CI = 3.2–5.8%), dependant upon the diagnostic criteria employed. Two-year incidence is 1.4% (95% CI = 0.6–2.6), and for first episode is 0.5% (95% CI = 0.1–1.3). Compared with the general population, the standardised incidence ratio for first episode psychosis is 10.0 (95% CI = 2.1–29.3). Full remission after 2 years is 14.3%. Visual impairment, previous long-stay hospital residence, smoking, and not having epilepsy were independently associated with psychosis, whereas other factors relevant to the general population were not.
The study of psychosis in persons with intellectual disabilities benefits the population with intellectual disabilities, and advances the understanding of psychosis for the general population. Mental health professionals need adequate knowledge in order to address the high rates of psychosis in this population.
Keywordsintellectual disabilities psychosis mental disorders epidemiology
The research at T1 was funded by Greater Glasgow Health Board and the West of Scotland R&D Mental Health Programme, and at T2 by the Chief Scientist Office, Scottish Executive Health Department (reference CZH/4/96). None of the authors have any conflict of interests to declare. We wish to thank Patricia Peters and Elaine Newall for secretarial support, and the professionals in the primary care liaison team of NHS Greater Glasgow and Clyde.
- 1.American Psychiatric Association (1980) Diagnostic, statistical manual of mental disorders, 3rd edn. A.P.A.,Washington DCGoogle Scholar
- 2.American Psychiatric Association (2000) Diagnostic and statistical manual of mental disorders, 4th edn. (revised). A.P.A., Washington, DCGoogle Scholar
- 9.Cooper S-A, Bailey N (2001) Psychiatric disorders amongst adults with learning disabilities: prevalence and relationship to ability level. Psychol Med 18:45–53Google Scholar
- 10.Corbett JA (1979) Psychiatric morbidity and mental retardation. In: James FE, Snaith RP (eds) Psychiatric illness and mental handicap. Gaskell, London, pp 11–25Google Scholar
- 11.Curtice L, Cooper S-A, Espie CA, Morrison J, Ibbotson T, Long L, Allan L (2001) Implementing partnership for health: piloting health checks for people with learning disabilities in Glasgow – final report. Greater Glasgow Primary Care NHS Trust R&D Directorate, Glasgow, ScotlandGoogle Scholar
- 14.Farmer R, Rohde J, Sacks B (1993) Changing services for people with learning disabilities. Chapman and Hall, London, pp 17–30Google Scholar
- 15.Glasgow CEDD (2001) The C21st Health Check. University of Glasgow, Glasgow, ScotlandGoogle Scholar
- 23.Leonard H, Petterson B, Bower C (2002) Prevalence of intellectual disability in Western Australia. Paediatr Perinat EpidemiolGoogle Scholar
- 26.McGrother C, Thorp C, Taub N, Machado O (2001) Prevalence, disability and need in adults with severe learning disability. Tizard Learn Disabil Rev 6:4–13Google Scholar
- 27.McLaren GL, Bain MRS (1998) Deprivation and health in Scotland: insights from NHS data. ISD Scotland Publications, EdinburghGoogle Scholar
- 31.Reiss S (1993) Handbook of challenging behaviour; Mental health aspects of mental retardation. IDS Publishing Corporation, Worthington, Ohio, pp 6–10Google Scholar
- 33.Royal College of Psychiatrists (2001) DC-LD [Diagnostic criteria for psychiatric disorders for use with adults with learning disabilities/mental retardation]. Gaskell Press, LondonGoogle Scholar
- 36.Simpson NJ (1999) Psychiatric disorders in people with learning disabilities: measuring prevalence and validating a screening instrument. Thesis/Dissertation, University of Manchester, pp 160–161Google Scholar
- 38.Sparrow SS, Balla DA, Cicchetti DV (1984) A revision of the Vineland social maturity scale by E A Doll. American Guidance Service, Inc., MinnesotaGoogle Scholar
- 41.Van Schrojenstein Lantman de-Valk HMJ, Wullink M, van den Akker M, van Heurn-Nijsten EWA, Metsemakers JFM, Dinant GJ (2006) The prevalence of intellectual disability in Limburg, the Netherlands. J Intellect Disabil Res 50:61–68Google Scholar
- 43.World Health Organisation (1968) Eighth revision of the international classification of diseases: glossary of psychiatric disorders. W.H.O., GenevaGoogle Scholar
- 44.World Health Organization (1992) Schedules for clinical assessment in neuropsychiatry. World Health Organization, GenevaGoogle Scholar
- 45.World Health Organisation (1993) The ICD-10 classification of mental and behavioural disorders: diagnostic criteria for research. WHO, GenevaGoogle Scholar