Wednesday, 13 April 2011

Bacteria, PANDAS and anti-psychotics

I don't know why but I seem to be repeatedly seeking out the most spine-tingling things to blog about. First it was gut parasites and fecal transplantation and now I am moving on to parasites "controlling" the mind. I really do need to cut out the horror flicks and drink more relaxing cups of tea.

This post stems from a programme broadcast on BBC Radio 4 titled: Voodoo wasps and Zombie worms. I attach a link to the programme here (bearing in mind that this link might change to something else in the not too distant future when a new programme uses the same link - so don't be surprised if I just linked to 'butter vs. margarine: the debate' or something like that).

The crux of the programme is that parasitic organisms might have the ability to affect the mind as well as the body. The programme uses the example of Toxoplasma gondii and how the bacteria might affect rats to relinquish their fear of cats, thus making them easier prey, and with it aiding the transfer of the bacteria (bacterium?) from rat to cat. T gondii (to those in the know) is then discussed in relation to schizophrenia, the manufacture of dopamine and just possibly, how some of the anti-psychotics might stop T gondii from replicating in the brain. This article from Faith Dickerson and colleagues sums it up.

I don't know about you but all that just gave me a chill down my spine. Real Sci-Fi stuff.

I had heard about T gondii before in relation to toxoplasmosis and why pregnant women should not handle used kitty litter. Those who remember that interesting film Trainspotting might also remember the link between one of the protagonists and death by toxoplasmosis following IV drug use.

The notion that bacterial or viral agents can conceivably affect the mind and behaviour has been mentioned in relation to lots of things, including autism spectrum conditions; think encephalitis for example. I even found this paper with onset of autistic symptoms and a possible temporal association post-malaria (remembering the adage 'correlation does not imply causation').

I say autism, but one of the most interesting areas relates to something called PANDAS. Before you start questioning why I am talking about those lovable, bamboo-eating bears, I will stop you and say I am not. PANDAS stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections.

PANDAS is a controversial concept. There are quite a few reports on the web talking about PANDAS and how it affected people. The suggestion is that a particular type of strep infection for one reason or another starts to manifest behavioural symptoms quite rapidly, possibly following a mechanism to that described in Sydenham's chorea. The basal ganglia is a target in PANDAS - as it is in autism also.

I find this whole area absolutely fascinating. The same kind of fascinating when studies suggest for example, that gut bacteria can affect behaviour. What it suggests is that we may think that 'we' control our actions and behaviour, but the question is, to what extent?

Coming back to autism, and assuming that there may be a specific 'type' of autism tied into such a mechanism, what are the possible implications? Well for one thing, it suggests that presentation of somatic conditions (moderated by viral or bacterial infection) in autism might be doing more than just affecting the physical body.
Kanner  talked about strep infection in one of his original cases - 'Alfred' - who was frequently ill with 'chickenpox, strep and impetigo'. Yes it could be coincidence; maybe, maybe not. Impetigo is something that I have been interested in for quite a while now - here and here - in relation to autism (or more accurately Asperger syndrome). I don't think I can make any link on the basis of the available data, but it is still interesting.

There might also be some implication for treatment of said infections and how it impacts on behavioural presentation. Remember Sandler and colleagues who reported on anti-microbial use impacting on the presentation of autistic behaviour? That combined with the suggestion that some of the anti-psychotic medications may impact on parasitic infections opens up a whole new world of possibilities.

In the words of Nick Ross ex-presenter from Crimewatch - "don't have nightmares".