"Our data show there may be a specific subtype of ASD [autism spectrum disorder] linked to comorbid psychosis. The results support findings that psychosis in people with ASD is often atypical, particularly regarding affective disturbance."
So said the findings reported by Felicity Larson and colleagues  (open-access available here) who bring an important topic into view that has recently been raised in the media too (see here). I appreciate that to talk about yet more comorbidity potentially following an autism diagnosis is not exactly great news. If however, one accepts that various comorbid conditions can actually be pretty disabling for many on the autism spectrum, identifying, screening and managing/treating said comorbidity then actually becomes pretty important.
Researchers set about looking to "describe autistic and psychotic phenomenology in a group of individuals with comorbid ASD and psychosis (ASD–P) and compare this group with populations affected by either, alone." Their group comprised of adults aged 16 and over diagnosed with an ASD and comorbid psychosis (N=116). This was an opportunistic cohort insofar as being recruited between January 2010 and June 2013. Eligibility was determined by a formal diagnosis of autism at referral and meeting "criteria on the Autism Diagnostic Observation Schedule (ADOS)... at the time of involvement in the study, or... meet criteria on the Autism Diagnostic Interview-Revised (ADI-R)... for a lifetime diagnosis." Psychotic illness determination was a 2-stage affair. First, inclusion was based on "a prior clinical diagnosis of psychotic illness or gave an account of an episode that was clearly psychotic" followed by evidence of psychotic symptoms being elicited using one or more questionnaires onward to the presentation of 'research-significant psychosis'.
Results: "What is clear from this research is that individuals who experience concurrent ASD and psychotic illness exist and are treated in mental health services." I don't think there is anything too earth-shattering about that statement but it does need to be said in the context of the label of autism rarely/not existing in some sort of diagnostic vacuum (see here). Next: "Mental health services in the UK are yet to be fully equipped to support people with both psychotic illness and ASD." Again, nothing new; following a trend of resources not being available or 'ready' to accommodate people on the autism spectrum and the health inequalities that inevitably follow. Insofar as the idea that psychosis presentation may at times be 'atypical' when it comes to autism, this also follows an important trend noted in other comorbidity research (e.g. when it comes to bipolar disorder for example).
The other data presented by Larson and colleagues on the profile of autistic symptoms potentially being slightly different when compared to a 'control group' of those diagnosed with autism but without evidence of psychosis - "the ASD–no psychosis (ASD–NP) group" (n=69) - is interesting but requires quite a bit more follow-up work. I might at this point drop in the paper by the wonderfully named Robustelli and colleagues  talking about how "youth at high-risk of developing psychosis have fewer and poorer quality social relationships" as being potentially relevant and indeed, how social functioning can be affected long-term when it comes to psychosis. Further investigation is also required around the observation that: "Individuals with ASD–P had lower rates of schizophrenia and higher rates of psychosis-NOS" in light of other work talking about spectrums (autism and schizophrenia) colliding (see here). Although not part of this study, the name of one co-author on this paper being linked to the Autism-Spectrum Quotient (AQ) is also potentially relevant, given other work asking whether the AQ might actually be picking up signs and symptoms of something like schizophrenia too (see here).
There is also the question of possible overlapping mechanisms potentially at work when it comes to autism and psychosis. In light of recent chatter about an immune system 'feature' to some psychosis (see here) and the myriad of immune related findings linked to autism, I'd suggest that this could be one area for further research inspection. The idea also that vitamin D for example, shows some relationship to some autism (see here for example) is another area for joint investigation given some chatter about levels of the sunshine vitamin/hormone and cases of psychosis . There will no doubt, be other areas of overlap potentially pertinent too...
There is quite a bit more to do in this increasingly important area of research.
 Larson FV. et al. Psychosis in autism: comparison of the features of both conditions in a dually affected cohort. Br J Psychiatry. 2016 Dec 15. pii: bjp.bp.116.187682.
 Robustelli BL. et al. Social relationships in young adults at ultra high risk for psychosis. Psychiatry Res. 2016 Dec 7;247:345-351.
 Suetani S. et al. Prevalence and correlates of suboptimal vitamin D status in people living with psychotic disorders: Data from the Australian Survey of High Impact Psychosis. Australian & New Zealand Journal of Psychiatry. 2016. Dec 21.
Larson, F., Wagner, A., Jones, P., Tantam, D., Lai, M., Baron-Cohen, S., & Holland, A. (2016). Psychosis in autism: comparison of the features of both conditions in a dually affected cohort The British Journal of Psychiatry DOI: 10.1192/bjp.bp.116.187682