Thyroid Hormone Deficiency and Brain-Based Symptoms
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.
Thyroid hormones play an important role in the function of many areas of the brain, including neuron health, brain immune cells called neuroglia, and 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: Impact on Neurotransmitters
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.
The Inflammatory Model of Depression and 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 and Mood Instability
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 and Hashimoto’s Disease
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.
The Role of the 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.
The Gluten Connection
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 patients find their mood disorders significantly improve by eliminating these two foods from their diet.
Hypothyroidism and Anxiety
Anxiety is increasingly common these days. Neurologically speaking, anxiety is caused by heightened activity in the amygdala and the limbic regions of the brain. The amygdala is responsible for regulating fear and aggression, and the limbic regions play a role in processing the whole spectrum of human emotions.
You can often calm yourself down during an anxious moment by taking the time to reason through the issue. This is because activating the frontal lobe through problem-solving reduces activity in the limbic regions – but brain fatigue, inflammation, unhealthy neurotransmitter activity, and slow nerve conduction all compromise the brain’s ability to prevent overactivation of the amygdala and limbic region.
The result? Massive anxiety.
Is Hypothyroidism or Hashimoto’s Behind Your Mood Disorder?
You can ask your doctor for a few tests if you think hypothyroidism is causing your depression, anxiety, or other mood issues.
A thyroid-stimulating hormone (TSH) test screens for hypothyroidism. However, keep in mind that TSH levels fluctuate frequently, and you may receive a false negative depending on when you test. If symptoms strongly suggest hypothyroidism, consider retesting.
It’s also important to screen for TPO and TGB antibodies, as the most common cause of hypothyroidism is autoimmune Hashimoto's. These levels can also fluctuate, especially in the early stages.
No Single Remedy for Depression and Anxiety
Unfortunately, there is no simple solution for anxiety and depression. Rarely will a single medication or supplement unwind the various mechanisms that underlie these conditions. Instead, you must go through the process of untangling the web.
This path is different for each person. It could include changing your diet, reducing inflammatory foods, or making other lifestyle changes. Perhaps you need to address your gut health, your microbiome, or your blood sugar. There are many different variables, and there is no one-size-fits-all treatment.
In conclusion, understanding the connection between hypothyroidism and chronic depression and anxiety is crucial in providing comprehensive care to individuals struggling with these mood disorders. By addressing and managing thyroid health, considering the impact of inflammation, neurotransmitters, blood sugar fluctuations, brain autoimmunity, the blood-brain barrier, and gluten sensitivity, healthcare providers can potentially offer more effective treatment strategies to improve the quality of life for those affected. Remember, there is no universal solution, but a tailored and multifaceted approach holds the key to better mental well-being.