Wednesday, 3 October 2012

When the autism and schizophrenia spectrums collide

Spectrum is Green @ Wikipedia 
Spectrum. The name conjures up white light separating out through a prism, the multi-coloured rainbow, and even that wonderful 8-bit computer made by Sir Clive Sinclair (yes, I had one of those you Commodore people).

When it comes to autism and schizophrenia, the concept of a spectrum invokes similar ideas of different variations or colours on a theme, separate but linked, patterns of symptoms which stem from a single source but diffuse outwards with fuzzy boundaries. It almost sounds a little bit 'Sixties' if I'm truly honest.

For quite a few people, including those on the DSM-V 'how are we going to redefine autism' committee, spectrum is something really being taken on board as the ever-approaching deadline for revision comes closer and closer into view. That's not to say everyone is particularly happy with the formal spectrum-ing of autism as per this recent review by Luke Tsai* (open-access) who prefers the term 'autism continuum disorder', but there you go. Indeed scroll down to the descriptor of autism at the bottom of this blog and I use the word 'tapestry' which also might be a good description of the heterogeneity present. (Note to self: this description will need updating next year).

You're probably wondering why I'm going on about spectrum; well its all to do with this paper by Prof. Kenneth Gadow** and how the autism spectrum and the schizophrenia spectrum might be colliding a little more than we perhaps first thought.

This is not the first time that I've talked about autism and schizophrenia overlapping as per this post on some very interesting research indicating that around about 40% of one cohort of people with schizophrenia also presented with symptoms congruent with an autism diagnosis.

Prof. Gadow reports a few interesting things from the other direction insofar as his cohort of children diagnosed with an autism spectrum disorder (ASD) presenting with quite a few characteristics more usually associated with the schizophrenia spectrum disorders (SSDs). In a little more detail (sorry that I can't link to the full-text paper):

  • Building on previous research by the author***, the aim of the study was multi-fold primarily looking at the risk of SSD symptoms in ASD and also looking at how a comorbid diagnosis of ADHD may moderate that risk of SSD symptoms.
  • Consecutive child referrals (aged 6-12 years) to a developmental or child psychiatry outpatient clinic were included for study.
  • Samples were divided up as follows: Autism (N=147) of which n=50 were diagnosed with an ASD only and n=97 diagnosed with ASD & attention-deficit hyperactivity disorder (ADHD). Controls (N=335) included n=146 asymptomatic and n=188 (I assume the missing participant was excluded for some important reason).
  • The primary schedule of choice was the Child and Adolescent Symptom Inventory-4R (CASI-4R) completed by mums and teachers of participants. In particular, the subscales on Schizoid Personality and Schizophrenia and their combining to form a global SSD score were a focus for this study.
  • Results (a few of them anyway): well, mums and teachers showed some overlap in their scoring of participants (always a relief for a questionnaire) bearing in mind contextual differences. Both children with ASD with and without ADHD "had more severe global SSD ratings than their respective controls" but as with many things linked to autisms, there was quite a bit of variability among participant scores.
  • A diagnosis of ADHD whether associated with ASD or not, seemed to confer a greater risk of SSD symptoms pointing to a likely link between ADHD and SSD. 
  • An interesting finding this one: the combination of ASD and ADHD and the pattern of SSD symptoms appearing (e.g. disorganised behaviour and negative symptoms - inappropriate laughter, crying and little interest in doing things) "supports the more general notion that certain combinations of disorders may be better conceptualized as unique clinical conditions". Now think back to that spectrum - continuum argument and the DSM-5 move away from discrete diagnoses....?
  • Another quote from the paper: "findings provide additional support for an interrelation between ASD and SSD symptoms".


A few things come to mind from these results. First is this suggestion that some cases of childhood ASD present with patterns of symptoms more readily tied into SSD. As per my previous post on this 'overlap', the great scientific machine seems to be doing yet another revolution as autism, once considered to be pretty 'similar' to schizophrenia (remember childhood schizophrenia) then departed on it's own journey, and now appears to be heading back towards schizophrenia or at least SSD.

I'm making no value judgements either way on this process given the likely opinions that might be raised on this matter in terms of diagnostic identity, management options and indeed how autism and schizophrenia have tended to become represented among the general population. If there is an upside to this partial reunification, I suppose it is that shared genetics (and epigenetics), biochemistry (see this post for example) and other areas might open up some interesting avenues for further study. With my own research hat on, I'm thinking Dohan and his hypotheses on gluten in cases of schizophrenia and autism. There are most likely going to be others.

Second is this issue of discrete clinical conditions potentially being present from the current study. Again its all about historical trends in science, and whether people talk about specific clinical entities (diagnostic boxes with names and formal criteria) or 'lumping things together' as per the use of terms like spectrum. I admit also to being pretty intrigued by the suggestion of a possible new clinical entity represented by ASD, ADHD and SSD symptoms. I'm no expert, and please don't take my word as Gospel, but there seem to be some hints of diagnoses like pathological demand avoidance (PDA) also being detailed here. Just a thought.

Finally bearing in mind the Gadow study was based on a paediatric population, one has to wonder how this complex pattern of symptoms will eventually play out into adulthood. Bearing in mind that autism is seemingly protective of nothing when it comes to comorbidity, I think many working at the coalface will know of people diagnosed with autism who seem to develop clinical signs and symptoms more readily associated with the schizophrenia spectrum disorders as maturity sets in. The question is whether the criteria used in the current study could somehow be predictive of those who are at greater risk and whether plans and processes could be set in place to moderate this risk.

I'm going to stop there save any charges of over-analysing the paper from Prof. Gadow and its important findings. Reiterating the complex nature of both ASD and SSD and the areas of overlap which seem to be present, how we understand such conditions and indeed label them actually might turn out to be an important point not just from a identity point of view but also conceptually, onward to planning for / mitigating risk and improving overall quality of life.

Without trying to make light of spectrums, may be you remember this theme tune by the Spectrum?

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* Tsai L. Sensitivity and specificity: DSM-IV versus DSM-5 criteria for autism spectrum disorder. Am J Psychiatry. 2012; 169: 1009-1011.

** Gadow KD. Schizophrenia spectrum and attention-deficit/hyperactivity disorder symptoms in autism spectrum disorder and controls. J Am Acad Child Adolesc Psychiatry. 2012; 51: 1076-1084.

*** Gadow KD. & Devincent CJ. Comparison of children with autism spectrum disorder with and without schizophrenia spectrum traits: gender, season of birth, and mental health risk factors. JADD. February 2012.

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ResearchBlogging.org Gadow KD (2012). Schizophrenia spectrum and attention-deficit/hyperactivity disorder symptoms in autism spectrum disorder and controls. Journal of the American Academy of Child and Adolescent Psychiatry, 51 (10), 1076-84 PMID: 23021482