A high-fat diet can cause depression, research reveals.
The fatty acids enter the brain through the bloodstream and accumulate in the hypothalamus.
There they affect critical brain signals that are linked to depression.
It helps to explain why scientists have found that depression and obesity are often seen together.
For the study, mice were fed a high-fat diet, made up of 60 percent saturated and unsaturated fats.
The results showed that the mice began to demonstrate depressive behaviour after three weeks.
Professor George Baillie, who led the study, said:
“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.
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 often use fatty food to comfort ourselves as it tastes really good, however in the long term, this is likely to affect one’s mood in a negative way.”
Examination of their brains revealed that the fats had built up in the hypothalamus.
The hypothalamus is an area of the brain that causes levels of cortisol — the ‘stress hormone’ — to rise in the body.
Normally the hormone reduces once a threat passes, but in people with depression, their cortisol levels can remain high.
Higher levels of cortisol are linked to depression.
This may help to explain why people who are obese do not respond as well to antidepressant medication.
Professor Baillie continued:
“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.”
The study was published in the journal Translational Psychiatry (Vagena et al., 2019).