Low Thyroid, Depression & Brain Fog

by Dr. David Minkoff April 26, 2023 5 min read

Low Thyroid, Depression & Brain Fog

Did you know low levels of thyroid can bring on not only low energy and weight gain, but also depression and even brain fog?

This can make thinking, problem-solving, and just coping with the everyday stresses of life, much harder.

With the rise in hormone-blocking toxins in our environment, processed foods and processed sugars, and the low amount of protein most of us consume, low thyroid is affecting more and more people, especially among women and the elderly.

In this article we dive into what thyroid is, how low thyroid occurs, how it affects our mood, mental alertness, and our ability to think and cope with the problems of everyday life and what we can do to raise it.

Let’s jump in.


The Thyroid is a gland located in the front of your neck which produces our thyroid hormones.

These play a very important role in weight gain and weight loss, our energy levels, our temperature, our skin, hair and nail growth, and our metabolism (the process in which our cells turn food into energy).

This is so much the case that thyroid actually drives the production of our mitochondria, the tiny organelles in our cells that make ATP (Adenosine triphosphate), the energy source our cells use to function.

Higher thyroid leads to higher levels of ATP (cellular energy), and lower thyroid leads to less ATP.

But thyroid even determines how many mitochondria our cells have with which to produce this energy.

The average cell in a healthy person has about 1000-2000 mitochondria to produce ATP.

But you can do a biopsy on someone with very low thyroid and come up with 500 mitochondria per cell — very low.

So this isn’t just energy production that thyroid regulates, it also regulates how many mitochondria we have in the first place with which to produce this ATP (cellular energy).

This is why we can have such low energy levels when our thyroid is low, and why it can take longer to build it back up again when addressing thyroid levels. We don’t just have to increase energy production, we have to increase energy producers.

So when we give thyroid to a patient, not only do their energy levels rise from increased production by the mitochondria they have, we also see increasing numbers of mitochondria.

But when thyroid is low, this can lead to more than just low levels of energy. It can also lead to depression and brain fog.


The brain is only about 3% of the body by weight. But as far as energy use, it’s about 20%. Meaning, the brain uses about 20% of the total energy our body produces.

But when our thyroid is low, the mitochondria in nerve cells in the brain produce less energy (ATP), and there are less mitochondria than there should be.

Thus, the brain is getting much less energy than it needs to do its job.

Low thyroid can also lead to decreased blood flow in the brain, preventing brain cells from getting the oxygen and nutrients they need. And it’s oxygen and nutrients (sugars, fats or amino acids) that the mitochondria use to produce ATP.

So we get even less energy production.

On top of that, thyroid is vital to the production and use of neurotransmitters in the brain such as serotonin, which raises mood, and norepinephrine, which helps us to be more alert and attentive.

And, as thyroid is essential for maintaining the health of neurons (nerve cells in the brain), as well as the formation of new connections between neurons (synapses), which information travels along in the form of electric impulses, this low thyroid can also contribute to a lessened ability to think as quickly.

Lastly, as thyroid also helps to regulate the other hormones, when thyroid is low, insulin and cortisol can rise, bringing on higher levels of stress.

All of this can show up as brain fog, inability to concentrate attention, think fast or be alert. It can lower our mood, bringing on depression, or stress us out with raised anxiety.

And, while there may be very real things in our environment that could be causing us to be depressed or anxious, we don’t need this to exaggerate those troubles, making them harder to cope with, or lowered mental ability to prevent us from figuring out solutions to our problems.


Thyroid is a very simple hormone made from iodine and the amino acid tyrosine.

Tyrosine is a non-essential amino acid which the body makes from the essential amino acid phenylalanine.

When we’re low on iodine or essential amino acids from protein, our body has less of what it needs to produce thyroid in the amounts we need for optimal energy production.

But there is more here. Certain toxins can disrupt the production and/or use of thyroid, or even make it so the cells aren’t able to receive or use it when thyroid levels are in optimal ranges.

As toxins are so high in today’s world, along with low levels of thyroid, we truly need to work harder than ever to ensure as few toxins are coming into our body as possible through properly filtered water, only organic foods to the best of our ability, and personal care products that do not contain harmful toxins in them.

Check out the Environmental Working Group for a full list of toxins to look out for in personal care products.

But there’s another key factor here.

There is something called estrogen dominance, where estrogen levels get too high in women and men. (Too high estrogen can also contribute to depression and anxiety.)

These too-high levels of estrogen are caused, mainly, by too much sugar (processed sugar really is the worst). And this high estrogen also brings on high cortisol (raises stress levels), lowers progesterone levels (a hormone that lowers stress levels), lowers testosterone levels and… destroys thyroid.


You see, estrogen does a few things with regard to thyroid. It can block the receptors on cells that thyroid uses to communicate with the cells. But it can also create something called thyroid binding globulins, which literally “eat up” the thyroid in your blood stream.

And there is the matter of vitamins, as well as magnesium, all of which contribute to properly functioning pathways in the cells which are needed for the optimal use of thyroid.

But these are the key things.

We need to lower the toxins coming into our body and work to remove the toxins we do have.

We need to lower sugar levels or at the very least remove processed sugars and processed foods from our diet, only eating organic foods to the best of our ability.

We need to get properly filtered water — reverse-osmosis is the best.

And we need to make sure our iodine levels are in optimal range and that we’re getting enough high quality protein in our diets.

Doing this can significantly improve thyroid levels, helping raise our mood, energy levels, and mental ability.

I hope this helps.

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*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.