Researchers have linked the consumption of diets high in saturated fats – which lead to obesity – with the development of depression phenotypes.

A study led by the University of Glasgow, in collaboration with the Gladstone Institutes, showed that saturated fatty acids enter into the brain's hypothalamus region, which is related to the metabolic system and is known to be linked to depression.

Published in the journal Translational Psychiatry, the research also showed that fatty acids affected key signalling pathways that are known to be responsible for the development of depression.

Another finding was that by decreasing the expression of a specific enzyme called phosphodiesterase, symptoms of obesity-linked depression could be reduced.

It is hoped that the study will finally shed some light on the links between obesity and depression. Previous clinical studies have found a strong association between the two conditions, but – until now – the exact mechanisms of how obesity affects depression and vice versa have not been fully understood.

“This is the first time anyone has observed the direct effects a high fat diet can have on the signaling areas of the brain related to depression," said professor George Baillie, lead author of the study.

"This research may begin to explain how and why obesity is linked with depression and how we can potentially better treat patients with these conditions.

“We all know that a reduction in fatty food intake can lead to many health benefits, but our research suggests that it also promotes a happier disposition.

"Further to that, understanding the types of fats, such as palmitic acid, which are likely to enter the brain and affect key regions and signaling will give people more information about how their diet can potentially affect their mental health.”

For the study – using mice – researchers studies were able to see that saturated fatty acids were actually entering the brain via the bloodstream and thereafter accumulate and affect crucial brain signals related to depression.

Mice fed a fat-dense diet (made up of 60 per cent saturated and unsaturated fats) were shown to have an influx of dietary fatty acids in the hypothalamus region of the brain, an area related to the metabolic system and known to be linked with depression.

These fatty acids were then able to directly affect the key signaling pathways responsible for the development of depression.

To read the full study, click here for Translational Psychiatry

• To read an article discussing whether exercise prescription could help tackle depression, click here for HCM magazine Issue 5 2018.