Behavioural equivalents of schizophrenia in people with intellectual disability and autism spectrum disorder. A selective review

Abstract

Assessment of schizophrenia (SCZ) in people with autism spectrum disorder (ASD) is complicated due to confounding symptoms between ASD and SCZ. These confounding factors are aggravated when the patient has sparse verbal skills. A selective review was conducted to identify behavioural equivalents when assessing SCZ in individuals with ASD with sparse verbal skills, from 16 years of age. Only clinical papers were reviewed. Eight relevant articles were analysed for the use of behavioural equivalents in clinical settings. The results showed that especially disorganized speech and behaviour and negative symptoms can be observed in patients with SCZ and ASD who speak sparsely. It is not possible to observe delusions, but they may be reported by the patients when treated adequately for some time, usually months. Hallucinations cannot be observed directly, but 'hallucinatory behaviour' may be interpreted as hallucinations when observed concurrently with other SCZ symptoms. Additionally, age of onset and marked impaired global functioning compared to habitual functioning may constitute a diagnosis of SCZ in ASD. ASD is considered a lifelong condition and may be identified within the first 3-4 years, while SCZ onset is usually in adolescence or early adulthood.

Schizophrenia in autistic people with intellectual disabilities: Symptom manifestations and identification

“…Disorganised behaviour may be misunderstood as behaviour problems and not further investigated (Bakken, 2021). Negative symptoms of schizophrenia, such as apathy, social withdrawal, and lack of motivation may be misinterpreted as autism-related social and adaptive difficulties (Chandrasekhar et al, 2020;Keller & Bari, 2019;Starling & Dossetor, 2009).…”

“…Though the diagnostic criteria distinguish the two conditions, surface symptom overlaps may constitute a considerable challenge in differentiating ASD and schizophrenia (Oliver et al, 2021; Bakken, 2021; Chandrasekhar et al, 2020; Trevisan et al, 2020; de Crescenzo et al, 2019; Keller & Bari, 2019; Kildahl et al, 2017; Nylander, 2014; Bakken & Høidal, 2014; Bakken et al, 2009; Bakken et al, 2007; Nylander et al, 2008; Underwood et al, 2015; Konstantareas & Hewitt, 2001; Cherry et al, 2000). Making judgements about whether certain, specific symptoms are associated with ASD or schizophrenia may be particularly challenging.…”

“…Disorganised speech may be misattributed to autistic communication difficulties, or idiosyncratic speech may be misinterpreted as disorganised speech (Chien et al, 2021; Starling & Dossetor, 2009). Disorganised behaviour may be misunderstood as behaviour problems and not further investigated (Bakken, 2021). Negative symptoms of schizophrenia, such as apathy, social withdrawal, and lack of motivation may be misinterpreted as autism‐related social and adaptive difficulties (Chandrasekhar et al, 2020; Keller & Bari, 2019; Starling & Dossetor, 2009).…”

“…Similarly to non‐autistic people with schizophrenia (Hardy‐Baylé et al, 2003), autistic people with intellectual disabilities and co‐occurring schizophrenia may appear disorganised and severely distressed during acute phases (Bakken, 2021; Bakken et al, 2007; Kildahl et al, 2017). While people in the general population may be able to report on core symptoms such as delusions and hallucinations, autistic people with intellectual disabilities may have difficulties verbally communicating during episodes of acute psychosis (Bakken, 2021; Kildahl et al, 2017; Underwood et al, 2015). Additionally, autistic people may have difficulties mentalising (Ribolsi et al, 2022; Robinson et al, 2017), and hence may lack awareness of what constitutes common or typical thought processes.…”

Recognizing Psychosis in Autism Spectrum Disorder

“…Autism spectrum disorder is composed by different levels of complexity, with frequent comorbidity with intellectual disability ( 13 ) and recently, there is growing attention on the behavioral equivalents of schizophrenia in people with intellectual disability and autism spectrum disorder ( 14 ).…”