Prevalence and comorbidity
Comorbidity, or the coexistence of two or more disorders, is common in both autistic individuals and people with psychotic disorders.
Psychosis and bipolar disorder are two commonly occurring psychiatric disorders that affect autistic individuals throughout their lives (Ghaziuddin & Ghaziuddin 2021; Foss-Feig et al. 2021; Jutla et al. 2021; Vaquerizo-Serrano et al. 2021; Bitsika et al. 2021). In fact, the prevalence of these disorders is significantly higher in autistic adults compared to the general population. For instance, the rates of psychosis in individuals with ASD are 5-35% higher than in the general population (Foss-Feig et al. 2021).
The onset of psychosis and bipolar disorder typically occurs during adulthood, with males being more likely to experience co-occurring psychosis and females being more likely to experience co-occurring bipolar disorder (Varcin et al. 2022).
Prevalence of autistic traits/ASD in people with psychotic disorders
The prevalence of autistic-like traits in individuals with psychotic disorders is significantly higher than in the general population The prevalence rates for these traits in individuals with psychosis range from 9.6% to 61%, while the rates for diagnosed ASD range from less than 1% to 52% (Kincaid et al. 2017).
Psychotic experiences in autism
Research suggests that ASD may significantly increase the risk of experiencing symptoms similar to psychosis (e.g., Jutla et al. 2021). There is evidence indicating that emotional disturbances in individuals with ASD may play a role in mediating these psychotic-like experiences. Specifically, anxiety has been found to induce formal thought disorder in individuals with ASD, and higher rates of psychotic experiences in ASD are associated with significant symptoms of anxiety and thought disorder (Sprong et al. 2008).
It is worth noting that some individuals with ASD who experience psychotic-like symptoms may meet the criteria for Clinical High-Risk for Psychosis (CHR-P). CHR-P is a status that confers a high, but not inevitable, risk of developing psychosis. This means that experiencing psychotic-like symptoms does not always lead to an acute psychotic episode. Instead, it describes individuals who present with potentially prodromal symptoms, indicating the early stages of psychosis (Fusar-Poli et al. 2013). Notably, while males were more frequently affected by ASD and CHR-P, ranging from 52.3% to 90.1%, it is interesting to note that females with ASD and CHR-P exhibited somewhat greater impairment (Sprong et al. 2008). (It is consistent with evidence from a prior study on subclinical psychotic symptoms in the general population, which demonstrated that females had higher rates of positive psychotic experiences (Maric et al. 2003).)
Symptoms indicative of prodromal (initial stage of) psychosis have been observed in ASD individuals at a prevalence ranging from 0 to 78.0% (Jutla et al. 2020; Wilson et al. 2020). These symptoms have been identified in young people, with a mean age range of 8.82 to 18.53.
Furthermore, autistic individuals who displayed symptoms of prodromal psychosis often have other non-psychotic symptoms. Among these, attention deficit hyperactivity disorder (ADHD) symptoms were the most commonly reported, affecting up to 52% of cases (Wilson et al. 2020).
ASD individuals with CHR-P have been found to exhibit more impaired social functioning (Foss-Feig et al. 2019) and poorer social cognition (Foss-Feig et al. 2019) compared to those with ASD but without prodromal psychosis. Additionally, CHR-P individuals with ASD show higher levels of impairment in facial affect recognition and slower responses to affective and non-affective face stimuli (Maat et al. 2020).
The CHR-P category also includes the Attenuated Psychosis Syndrome (APS), which refers to a condition where individuals experience mild psychotic symptoms that are not severe enough to meet the criteria for a full-blown psychotic disorder. Interestingly, when considering different CHR-P groups, it has been found that up to 100% of individuals with ASD and CHR-P meet the criteria for APS (Foss-Feig et al. 2019; Maat et al. 2020).
APS is considered a risk syndrome, as it indicates an increased likelihood of developing a psychotic disorder in the future. (APS is currently not a recognized psychological/psychiatric disorder, but it is included in DSM in the section Conditions for Further Study.) By recognising and addressing these milder symptoms, healthcare professionals hope to prevent or delay the onset of full psychosis and minimize its impact on an individual's life.
Conversion rate to full psychosis
The conversion rates to psychosis among individuals with ASD and CHR-P were found to be between 15.4% and 18.2% after a 2-year follow-up period, while the conversion rates in individuals with CHR-P but without ASD ranged from 11.1% to 14.0% after 2 years (Foss-Feig et al. 2019; Guillory et al. 2018).
The conversion rate to full psychosis among individuals with ASD and APS is 30.7%. Surprisingly, the severity of autistic and psychotic symptoms did not influence the likelihood of conversion to full psychosis. Interestingly, the young individuals with ASD/APS who later developed full psychosis exhibited lower cognitive performance and greater impairment in adaptive social functioning compared to their counterparts with ASD alone (Riccioni et al. 2022).
These findings emphasise the importance of early intervention and support for this population. These interventions may include psychoeducation, cognitive-behavioural therapy (CBT), family support, medication management, and social skills training. The aim is not only to alleviate immediate distress but also to equip individuals with coping strategies that can enhance their overall well-being and resilience in the face of future challenges.