Sunday, 7 August 2011

Trends in autism and schizophrenia research

It is easy when writing a blog like this to become a little too focused on the object of your attention at the expense of the bigger picture. I assume there is some trendy name for such a psychological phenomenon - oh, yes 'not seeing the wood for the trees'. Over several years I (like many others) have become more and more convinced that whilst genetics is an important area of autism research, the various genetic models put forward so far have been sadly lacking in their appreciation of a contributory role for the environment in a kind of symbiotic relationship. I base such a view on the volumes of research that has passed through my humble PC over the years alongside the volumes of commentary which I have read about the research. One could perhaps argue that my view has become self-selecting and self-fulfilling as the years have gone by; that is, I see what I want to see, at the expense of any research which opposes my view.

One of the best remedies for this is to examine what is happening in other areas, in this case to have a look at other areas of research outside of autism or at least on the very periphery. I do try and do this as much as I can, to try and level my view and restore some degree of objectivity. One of the main areas of research that I try and keep tabs on is what is happening in the world of schizophrenia research.

Why schizophrenia you might ask? Well, schizophrenia and autism have some history, but more than that they are both spectrum conditions rather than one-presentation entities and both have some big question marks hanging over them about prevalence, aetiology and risk factors. I have blogged about schizophrenia previously.

So what is happening in the world of schizophrenia research and what might it tell us about autism research? There is quite a good review of all things schizophrenia here by NICE. This fairly recent, and quite hefty, document covers quite a few details and makes some interesting points:

  • Diagnosis remains solely on the analysis of 'behavioural' history.
  • Although the topic of some debate, prevalence of schizophrenia, core schizophrenia, is round about 1% over a lifetime. 
  • Various co-morbidities both psychiatric and somatic can surround a diagnosis; schizophrenia is not protective against the development of other conditions.
  • Although no one model for the aetiology of schizophrenia exists, a 'vulnerability-stress' model has been proposed whereby genes and biochemistry act as 'risk' factors modified by psychological and social factors.

I am sure that the discerning reader can see a few overlaps here with the autism spectrum conditions although not all features are the same. I might also add that schizophrenia has been tied into a few other overlapping areas related to autism; so things like a role for the immune systema possible link with gluten (from Faith Dickerson and her research group), and issues with the hyperpermeability of the gastrointestinal tract. Indeed the 'second brain' seems to show more than a passing relationship with some cases of schizophrenia.

One of the bigger questions in schizophrenia surrounds what factors might influence the initial 'vulnerability' to schizophrenia and what does this tell us about our potential risk. I say this because of this paper recently released in Nature Genetics by Girard and colleagues. The paper suggests that de novo mutations in various genes were more commonly detected in cases of schizophrenia than controls, and said mutations might account for the increase in cases of the condition being observed. When I saw this paper, the first thought to cross my mind was how strikingly similar these findings were to those recently reported in relation to autism (see here) in terms of the meaning of the findings: de novo = not inherited from parents. Indeed this paper out today also in Nature Genetics picked up by the BBC says pretty much the same thing.

Coupled with various other failures to detect consistent genetic markers, this paper actually summarises quite well the current state of play with regards to genes and schizophrenia; the initial promise (and hefty research price tag) of a 'schizophrenia gene' with classical genetic transmission pattern being unmet and more likely now down to various gene-environment interactions. Spontaneous mutation, perhaps suggesting some interesting environmental connections (see my recent post on our chemical romance, and no not 'my chemical romance'), is a research line which seems to be going places. Please do not assume from this that I am saying that traditional genetics are defunct when it comes to schizophrenia because I am not. There is still evidence to suggest that risk of schizophrenia is increased in families with a history of the condition alongside ethnicity also being a factor. The sum total of the research so far does however mean that the vulnerability basis for schizophrenia is not solely genetic.

I would like to think that schizophrenia research or research in other areas is a good balance to that of autism research. The trends being picked up in autism are being mirrored in schizophrenia and other areas and vice-versa. Our rigid models of such conditions being somehow the result of consistent single or multiple genes are slowly being overturned and the concept of genetic diversity is beginning to shine through, influenced in part by the environment around us.

If you need more evidence of some interesting environmental overlaps, consider this paper on birth spacing in schizophrenia and compare it with the similar findings in autism (even mentioning our old friends folate metabolism and pre- and peri-natal nutrients). Interesting.