Dietary fats entering the brain may explain link between obesity and depression

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Obesity and depression have long been linked, with previous clinical studies finding an association between these two conditions. However, until now, the mechanisms of how obesity affects depression and vice versa have not been fully understood.

Now, in a new study led by the University of Glasgow in collaboration with the Gladstone Institutes, and published today in Translational Psychiatry, scientists have been able to demonstrate the links between the consumption of diets high in saturated fats that lead to obesity and the development of depression phenotypes. They have also found that by decreasing the expression of a specific enzyme called phosphodiesterase, symptoms of obesity-linked depression can be reduced.

In novel findings, shown in mouse models, researchers were able to see that saturated were actually entering the brain via the bloodstream and thereafter accumulate and affect crucial brain signals related to depression. Mice fed a fat-dense (made up of 60% saturated and ) 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.

The relationship between obesity and depression is known to be complicated, with patients with obesity less likely to respond well to common antidepressant medication. Indeed, patients with obesity show a substantially slower response to antidepressant treatment, with less overall improvements.

Researchers in this study believe that their novel findings may now influence new targets for antidepressant medications that may be more suitable for overweight and obese individuals.

Professor George Baillie, lead author of the study from the University of Glasgow, said: "This is the first time anyone has observed the direct effects a 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. Of course, if you are feeling low, then to make yourself feel better you might treat yourself to more fatty foods, which then would consolidate negative feelings.

"We all know that a reduction in fatty food intake can lead to many , 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."

In this study, researchers found that either dietary or genetically induced in mice lead to depression phenotype, and that this phenomenon occurred via the disruption of the cAMP/PKA signaling pathway. In addition, they found that the consumption of a fat-dense diet led to an influx of dietary fatty acids specifically in the hypothalamus. These fatty acids could then directly modulate the PKA signaling pathway responsible for the development of depression. These findings suggest that the influx of saturated fatty acids due to the consumption of a high fat diet can alter the cAMP/PKA signaling process, which results in the development of phenotype.

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More information: Eirini Vagena et al. A high-fat diet promotes depression-like behavior in mice by suppressing hypothalamic PKA signaling. Translational Psychiatry,volume 9, Article number: 141 (2019).
Journal information: Translational Psychiatry

Citation: Dietary fats entering the brain may explain link between obesity and depression (2019, May 10) retrieved 16 October 2019 from
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May 10, 2019
This adverse effect seems to be mainly from just palmitic acid:

> types of fats, such as palmitic acid, which are likely to enter the brain and affect key regions and signaling

May 11, 2019
So how does this correlate with the keto diet and associated weight loss?

"The ketogenic diet is a very low-carb, high-fat diet that shares many similarities with the Atkins and low-carb diets. It involves drastically reducing carbohydrate intake and replacing it with fat. ... It lowers blood sugar and insulin levels, and shifts the body's metabolism away from carbs and towards fat and ketones."

May 11, 2019
Otto there seems to be an obsession with low fat - high carb diets in the liberal and vegan world. They have killed millions with this diet and continue to push it every chance they get.

May 11, 2019
When one understands that starches and sugars are the food equivalent of heroin the obesity that they create is easier to understand. One has to quit heroin altogether there is no such thing as controlled usage. The exact same thing applies to starches and sugars and their link to obesity. Fats are your friend not your enemy if you are trying to lose weight.

Otto, it is beginning to look like fat vs. carbs for weight loss is at least somewhat dependent on individual genetics. Personally, I can handle keto for a couple of weeks or so, then I feel like I'm going to die. I do best eating a balanced diet of just about nothing. Vegan works better for me than keto, but I do have to cheat about once a month to keep from feeling like crap.

I do notice an improvement in mood when eating almost nothing, or eating vegan. Mood also improves if I eat about 8 grams of fish oil per day. Not sure why, but flaxseed oil does nothing for me. Running several miles a week probably has the largest positive effect on both mood and weight loss.

May 13, 2019
Well when I started keto I was losing about 2-3 pounds a week and lost about 20 pounds without any problem. Food became an afterthought. I did not really have cravings or feel hungry. If you are burning your own fat for fuel eating becomes less important and easier to control. If fact if one has a project to do it is very easy to skip meals altogether and not feel any decrease in energy levels. Now I determine how much I eat by deciding whether or not I need to gain or lose weight that week. It has become harder to lose weight in the past few months however. My metabolism has slowed down and I need less food to maintain my weight. BTW that is a GOOD thing, not a negative at all.

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