Thursday, 26 March 2015

Autism increases risk of nonaffective psychotic disorder and bipolar disorder

Published at the same time and in the same journal as the 'MoBa does bowel issues in autism' paper from Bresnahan and colleagues [1], the study results from Jean-Paul Selten et al [2] reporting that "A diagnosis of ASD [autism spectrum disorder] is associated with a substantially increased risk for NAPD [nonaffective psychotic disorder] and BD [bipolar disorder]" has, at the time of writing this post, received little or no press attention in comparison despite being pretty important findings.

Continuing an important theme that a diagnosis of autism is in no way protective against the development of mental health issues (see here), the Selten results suggest that quite a bit more diagnostic vigilance might be required in order to ensure that further health inequalities do not appear for those on the autism spectrum.

Containing a familiar author name - Cecilia Magnusson, who is no stranger to autism research - the authors set about analysing data from the Stockholm Youth Cohort [3] and specifically "included cohort members ever diagnosed as having ASD (n = 9062) and their full siblings never diagnosed as having ASD." Cases were matched 10 to 1 with controls of the same sex and born in the same month/year. Researchers looked for diagnoses of NAPD and BD and importantly "adjusted for age, sex, population density of place of birth, personal or parental history of migration, hearing impairment, parental age, parental income, parental educational level, and parental history of psychiatric disorder."

Results: distinguishing between cases of autism with intellectual (learning) disability and those without, those diagnosed with autism without intellectual disability (ID) were calculated to show "a substantially increased risk for NAPD and BD" compared with controls. Depending on whether ASD was "registered before age 16 or 28 years" also seemed to play a role in the risk (odds ratios, ORs) statistics. Those "non-ID ASD registered before age 28 years" presented with ORs of 12.3 and 8.5 respectively for NAPD and BD. Those "non-ID ASD registered before age 16 years" presented with ORs of 5.6 and 5.8 respectively. The comparative statistics for full siblings of those with ASD for NAPD and BD were also elevated (ORs: 1.8 and 1.7 respectively) but nothing like to the degree noted for those with a diagnosis of ASD.

As I've mentioned, these are important findings. I've talked a few times on this blog about conditions like psychosis being diagnosed alongside cases of autism (see here and see here). The data from Khandaker and colleagues [4] (see here) reporting on a "Higher risk of PEs [psychotic experiences] in early adolescence among individuals with childhood ND [neurodevelopmental disorders]" adds to the evidence that there may be shared mechanisms at work when it comes to something like autism and schizophrenia for example (see here). This might also mean that our views about autism across the lifespan should more thoroughly incorporate the higher risk of mental health issues potentially being noted. Anyone who follows this blog and my ramblings about the health inequalities associated with something like schizophrenia (see here for example) will know what this might mean for some on the autism spectrum too.

Insofar as the findings on bipolar disorder potentially being more frequently noted when autism is mentioned, I'm not at all surprised. 'Bipolar disorder is frequent in adult Asperger syndrome' was a post I previously wrote on this topic and how, based on research like that from Vannucchi and colleagues [5], anywhere between 6-20% of those with Asperger syndrome (AS) can potentially expect to be diagnosed with BD at some stage. Actually I'd probably suggest the rate might be higher than those statistics suggest given the assertion that BD in autism/AS is: "often characterized by atypical presentation, making its correct identification particularly difficult."

Need I say any more?

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[1] Bresnahan M. et al. Association of Maternal Report of Infant and Toddler Gastrointestinal Symptoms With Autism Evidence From a Prospective Birth Cohort. JAMA Psychiatry. 2015. March 25.

[2] Selten JP. et al. Risks for Nonaffective Psychotic Disorder and Bipolar Disorder in Young People With Autism Spectrum Disorder: A Population-Based Study. JAMA Psychiatry. 2015 Mar 25.

[3] Idring S. et al. Autism spectrum disorders in the Stockholm Youth Cohort: design, prevalence and validity. PLoS One. 2012;7(7):e41280.

[4] Khandaker GM. et al. A population-based longitudinal study of childhood neurodevelopmental disorders, IQ and subsequent risk of psychotic experiences in adolescence. Psychol Med. 2014 Nov;44(15):3229-38.

[5] Vannucchi G. et al. Bipolar disorder in adults with Asperger׳s Syndrome: A systematic review. J Affect Disord. 2014 Jul 8;168C:151-160.

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ResearchBlogging.org Selten JP, Lundberg M, Rai D, & Magnusson C (2015). Risks for Nonaffective Psychotic Disorder and Bipolar Disorder in Young People With Autism Spectrum Disorder: A Population-Based Study. JAMA Psychiatry PMID: 25806797