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If you struggle with chronic depression, anxiety, it could be a poor managed hypothyroid case!

If you struggle with chronic depression, anxiety, or other mood disorders, you may suffer from undiagnosed or poorly managed hypothyroidism. A thyroid hormone deficiency can cause multiple brain-based symptoms

A thyroid hormone deficiency can cause multiple brain-based symptoms. This is because thyroid hormones play an important role in the function of many areas of the brain, including:

  • Neuron health

  • Brain immune cells called neuroglia

  • The blood-brain barrier

If you have a chronic mood disorder, consider asking your doctor to screen for hypothyroidism with a TSH test and for autoimmune Hashimoto’s with a TPO and TGB antibody test in order to rule these conditions out.

Hypothyroidism and depression


Thyroid hormones impact major neurotransmitter receptors in the brain such as serotonin, dopamine, GABA, and acetylcholine. These neurotransmitters help regulate your mood, motivation, and executive function.

The majority of research during the last 30 years has largely focused on the neurotransmitter model of depression, which emphasizes serotonin and dopamine imbalances and the development of pharmaceutical antidepressants to correct such imbalances.

However, most patients experience only limited success managing their depression with these drugs.

Brain inflammation

An explosion of research has found a connection between depression and inflammation, called the inflammatory model of depression.

In these patients, brain inflammation slows nerve conduction and synaptic speed. This decreased speed causes depression by slowing activity in the relevant regions of the brain. Because these cases are a result of inflammation, traditional antidepressants are ineffective.

Inflammation-related depression can be caused by a traumatic brain injury, stroke, or systemic inflammation throughout the body.

Unmanaged Hashimoto’s is another possibility that causes systemic inflammation. The fluctuations typical with the condition also mean thyroid levels wax and wane, and periods of low thyroid levels can result in significant depression. This could explain why your depression persists even after you begin treating your hypothyroidism.

Blood sugar fluctuations

Whenever a patient mentions mood instability, my first instinct is to check their blood sugar.

This is because blood sugar highs and lows are very common causes of mood fluctuations. Anyone who has been “hangry” can attest to this.

Hashimoto’s patients often have unstable blood sugar levels, which makes them more prone to insulin resistance and both high and low blood sugar.

Brain autoimmunity

When the immune system attacks the thyroid gland, it is targeting TPO enzymes and TGB proteins. Antibodies to TPO and TGB are used to screen for Hashimoto’s.

Unfortunately, sometimes these TPO and TGB antibodies bind to cerebellum tissue in the brain, causing some Hashimoto’s patients to develop brain autoimmunity.

This inflames and degenerates the brain and can cause depression.

Blood-brain barrier

Systemic inflammation from unmanaged Hashimoto's is associated with intestinal permeability, otherwise known as leaky gut.

Leaky gut patterns have been shown to make the blood-brain barrier overly permeable, which makes the brain much more prone to inflammation, thus causing depression. We published a 2020 study in the International Journal of Molecular Science that showed a connection between inflammatory bowel disease and a “leaky” blood-brain barrier in patients with autoimmune disease.


Two-thirds of people with a gluten sensitivity experience neurological symptoms instead of gut symptoms. This is because the tissue most affected by a gluten sensitivity is nerve tissue.

The majority of Hashimoto’s patients are gluten-sensitive or have celiac disease, which means gluten can play a role in their depression and anxiety.

Gluten cross reacts with dairy, meaning the immune system recognizes dairy as gluten. Many pa