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Diagnoses of schizophrenia, schizotypal and delusional disorders among people with intellectual disabilities compared to the general population: A register study in Skåne, in southern Sweden

EAMHID 2023 – Helsinki, September 21 – 23 2023

Magnus Sandberg, Jimmie Kristensson, Anna Axmon

[Presentation (pdf)] [Project main site]

Background: People with intellectual disabilities (ID) may be at higher risk of psychiatric disorders than the general population. However, few studies investigate the role of demographic factors.

Methods: This register-based study includes all people living in Skåne, Sweden, on January 1st, 2014. The ID cohort comprises those who received support and service for people with functional impairments and those with diagnosis of ID or Down Syndrome (n=14715). The remaining population of Skåne formed the general population cohort (GenPop; n=1258644). Data on diagnoses of schizophrenia, schizotypal and delusional disorders were collected for 2014-2021. All analyses considered sex, age group and own and parent origin as potential confounders and effect modifiers.

Results/Aims:The aim of this study is to compare diagnoses of schizophrenia, schizotypal and delusional disorders among people with ID compared to the general population accounting for demographic factors. People with ID had higher risk of all investigated diagnoses. The prevalence of schizophrenia was 3.1% and unspecified nonorganic psychosis 2.8% in the ID cohort compared to 0.3% and 0.2% in GenPop cohort (RR 9.2, 95% CI 8.7-10.5 and RR 12.8 95% CI 11.5-14.2 respectively). The risk increases remained after adjusting for demographic factors (RR 13.6 95% CI 12.3 15.0 and RR 16.0 95% CI 14.4-17.9).  Stratified analyses revealed that the risk of schizophrenia associated with ID was higher among women, whereas that of unspecified nonorganic psychosis was higher among men. Adults with ID were more at risk than children/adolescents and older people of being diagnosed unspecified nonorganic psychosis, while older people were more likely to be diagnosed with schizophrenia.

Conclusions: Even when considering demographic factors, people with ID are in general more at risk of diagnoses of schizophrenia, schizotypal and delusional disorders compared to the general population, in particular schizophrenia and unspecified nonorganic psychosis.  


Research group

Associate professor Magnus Sandberg (PI for IDcare)

Associate professor Anna Axmon (PI for the covid follow-up study)

Professor Ulf Gerdtham

Associate professor Jimmie Kristensson


Dr Trine Lise Bakken, Head of Research at Oslo University Hospital, Norway (studies on schizophrenia, schizotypal and delusional disorders)

Professor David Edvardsson, La Trobe University, Melbourne, Australia (studies on ageing)

Associate professor Kristina Edvardsson, La Trobe University, Melbourne, Australia (studies on pregnancy)

Dr Katarina Lauruschkus, Child and Family Health, Department of Health Sciences, Lund University (studies on habilitation)

Dr Emilie Stroh, Occupational and Environmental Medicine, Lund University (studies on children and adolescents)