Tuesday, 13 March 2012

Autism and psoriasis

Spring blossom has sprung @ Paul Whiteley
Trawling the web, as one does, looking at new research studies on this, that and t'other often provides a few 'memory lane' moments.

For example, some weeks back I stumbled upon some interesting discussions on whether okra might have the ability to induce male sterility. Strange you might think that lady's fingers might be a good male contraceptive, but there is some good science behind it specifically based on the actions of a compound called gossypol.

Why is gossypol part of my vocabulary? Well my better-half did some research on this compound a few years back, primarily derived from the cotton plant (Gossypium), with a view to its potential anti-psoriatic abilities. Real pharmacognosy in action. The anti-psoriatic abilities of gossypol got me thinking about psoriasis with autism spectrum conditions in mind.

Psoriasis is a topic which has cropped up before on this blog with regards to autoimmunity and how having one autoimmune-related condition might raise your risk of developing another (or others). Psoriasis is a bit of a blanket description for several manifested skin conditions. It is basically a fault in the production of skin cells; cells pile up on top of each other forming patches or plaques which can cause some quite serious physical discomfort, also having been linked to secondary bacterial infections. More recently is the suggestion that the disease might not just be skin related and not necessarily having just a physical effect. Prevalence and incidence studies are rife on psoriasis; this study suggested a prevalence of 2.5% among a European (German) population.

There is a limited body of literature which suggests that psoriasis might be more common in autism, and families of people of autism, than compared to control populations. The paper that struck me is this one from Lisa Croen and colleagues* looking at immune comorbidities in autism. I say paper but in this form it was actually a conference proceeding from IMFAR 2008. The findings however, based on quite an impressive sample size (autism; n=5565; controls; n=27,825) suggested some interesting differences when it came to the prevalence of autoimmune conditions. Psoriasis came top of the pops; being diagnosed twice as often in autism cases vs. controls.

Croen appears again with regards to the literature on familial psoriasis and 'risk' of autism. This paper** (open-access) suggested that within a 4-year period surrounding pregnancy, maternal psoriasis appeared with greater frequency in cases of autism vs. controls. That being said, their overall conclusions were that maternal autoimmune disorders were unlikely to be strongly related to risk of autism in offspring. I'm not too sure about this last statement in light of more recent findings. Bakkaloglu and colleagues also reported one case of psoriasis in one parent of a child with autism in their study of 30 children compared with none in 39 controls.

Appreciating that the absolute numbers of people with autism with comorbid psoriasis is likely to be quite small (that's what we found at least) I do wonder about the whole autoimmune effect. I would be hard-pressed to say that autism, all autism, is an autoimmune condition because the universal population data really don't bear this out. Having said that, the move towards biological phenotypes would perhaps be an ideal vehicle to see if autoimmune comorbidity reflects a sub-group of those on the autism spectrum. So those cases where coeliac disease, Crohns disease, ulcerative colitis, type-1 diabetes or psoriasis are mentioned: a phenotypic subgroup perhaps? Again not directly linked, but schizophrenia has also been tied into psoriasis albeit with the similar caveats to that of autism. I do also wonder whether the the phototherapy sometimes used for psoriasis might also have some relation to vitamin D status and onward links?

I finish with some Orange Crush from REM (they were great, weren't they).

* Croen LA. et al. Immune comorbidities in children with autism spectrum disorders. IMFAR 2008

** Croen LA. et al. Maternal autoimmune diseases, asthma and allergies, and childhood autism spectrum disorders. Archives of Pediatrics and Adolescent Medicine. 2005; 159: 151-157