Monday, 3 October 2011

Schizophrenia and epilepsy

Whilst few universal commonalities outside of overt clinical presentation are seemingly present in autism spectrum conditions, there are various co-morbidities which appear to be more strongly associated with a diagnosis. Learning or intellectual disability is perhaps the most frequently cited; but in terms of overall health (and risk of early mortality), the presence of epilepsy or seizure-type disorders is one of the most worrisome.

I have talked about epilepsy and autism on this blog previously. In this post however I turn my attention to a new piece of research which suggests that schizophrenia might also be a risk factor for epilepsy and likewise epilepsy might be a risk factor for schizophrenia. The study is this one by Yu-Tzu Chang and colleagues* published in the journal Epilepsia.

The details of this two-part study include:

  • Based on Taiwanese health data, analysis 1 looked at over 5,000 people with an incidence of schizophrenia during the period 1999-2008 compared with over 20,000 asymptomatic controls. They reported that the incidence (note incidence not prevalence) of epilepsy in the schizophrenia group was some six times higher than the control group (6.99 vs. 1.19 per 1,000 person-years).
  • Analysis 2 looked at over 11,000 patients newly diagnosed with epilepsy compared with over 46,000 age- and sex-matched controls. The incidence of schizophrenia was again much higher in the epilepsy group compared with controls (3.53 vs. 0.46 per 1,000 person-years).
  • Gender seemed also to exert an effect: women with schizophrenia were more likely to present with epilepsy but men with epilepsy were at greater risk of presenting with schizophrenia.

Cumulatively what this data suggests is that the links, the bi-directional relationship, between schizophrenia and epilepsy might be quite strong. Given the information presented in my previous post on the use of EEGs and epilepsy (and autism) and the link between epilepsy and the electrical circuits of the brain, one can perhaps see how such a relationship might make sense. What we know about schizophrenia, the neurology, the neurochemistry, the biochemistry, the genetics is however the same as what we know about autism; that is, it is very, very complicated.

As the BBC report on this paper adds, psychosis has been previously linked to epilepsy exemplified by studies like this one. Whether there are shared genes, shared environmental factors between the conditions is at this moment unknown but I wouldn't be surprised if there were. I do wonder about the possible influence of things like diet in relation to this work. Dohan's hypothesis on schizophrenia and gluten and casein, the link between some cases of epilepsy and the use of a keotgenic / modified Atkins diet (low carbohydrate diet), what happens to epilepsy in some cases of autism where a gluten-free diet is implemented; all factors circling this important study and its important relationships.

* Yu-Tzu Chang et al. Bidirectional relation between schizophrenia and epilepsy: A population-based retrospective cohort study. Epilepsia. September 2011.