Assessing whether levels of polyunsaturated fatty acids alter risk of schizophrenia

Research funded by the National Institute for Health Research Bristol Biomedical Research Centre (NIHR Bristol BRC) aims to determine whether levels of omega-3 and omega-6 polyunsaturated fatty acids affect risk of schizophrenia in some people.

Schizophrenia is a serious mental illness that places a substantial burden on patients, their families, and the health-care system. There is currently a lack of understanding as to what causes schizophrenia and therefore little is known about potential health behaviours that could help to prevent its development.

Omega-3 and omega-6 polyunsaturated fatty acids play many important roles in the body and are essential for normal development and function of the brain. This is especially true for long-chain fatty acids which we convert from short-chain fatty acids that we get from our diet. Many studies have shown that blood levels of omega-3 and omega-6 polyunsaturated fatty acids are different in individuals with schizophrenia compared to individuals without. However, it is not clear whether these fatty acids play a causal role in developing schizophrenia or whether the difference in levels is due to dietary changes after people become ill.

In order to conduct the study, the research team used Mendelian randomization, a technique that uses variations in our genes to better understand whether associations are causal or not. The analysis indicated that higher levels of long-chain omega-3 and omega-6 fatty acids were associated with a lower risk of schizophrenia, whilst there was weaker evidence that short-chain fatty acids were associated with an increased risk of this disorder.

The results are compatible with the hypothesis that long-chain fatty acids have protective effects on schizophrenia. This suggests that people with schizophrenia may have difficulty converting short-chain polyunsaturated fatty acids to long-chain ones, with the resulting deficiency in long-chain fatty acids increasing risk of developing this disorder.

It was concluded that further studies are required to determine whether taking supplements for long-chain polyunsaturated fatty acids or improving our diet to include more of these might help prevent onset of schizophrenia.

Dr Hannah Jones who led the study said:

“Our study provides evidence that long-chain fatty acids are causally associated with schizophrenia which opens up the possibility that targeting these through supplementation or dietary changes may improve outcomes for people at risk of developing this illness. Although the method we used does not tell us when and for how long such supplementation may be beneficial, our findings will hopefully encourage future research in this area to better understand the link between diet and mental health.”

Paper

Associations between plasma fatty acid concentrations and schizophrenia: a two-sample Mendelian randomisation study Hannah Jones et al., The Lancet Psychiatry.