In adults, thyroid hormones have a major influence over virtually every brain activity. For instance, thyroid hormones T3 and T4 are involved in the formation of neurons, neuronal migration, nerve fiber growth, myelination and more.
This ultimately may involve a complex web of dysfunction that requires careful attention to the root causes of the debilitating symptoms. When thyroid hormone isn't properly converted and absorbed, it can make brain-related symptoms worse.
Hashimoto's and hypothyroidism can lead to various disorders, including lethargy and poor reflexes and motor coordination. They're also linked to bipolar disorders, depression and loss of cognitive function, especially in the elderly.
In extreme cases, Hashimoto's can lead to a condition called Hashimoto's encephalopathy, which can cause severe changes in the brain that look a lot like the destruction caused by Alzheimer's, where the brain actually loses massive amounts of brain tissue.
One of the most common symptoms of Hashimoto's is brain fog: the feeling that you're thinking through a haze and can't quite focus or concentrate no matter how hard you try.
Brain fog is an indication of inflammation in your brain, and immune cells in the brain called 'microglia' are responsible for this.
The immune system in the brain is different from the one in the rest of the body, which is much more complex; it has many different parts that balance and regulate each other. In your brain, the immune system is simpler. Microglial cells have hair-trigger sensitivity and are capable of inflicting major damage. These cells appear to be involved in Alzheimer's, Parkinson's, cardiovascular disease and more. They respond quickly to pathogens and injury, accumulate in regions of degeneration and produce a wide variety of proinflammatory molecules.
Thyroid hormones have a major influence on microglial cells. They can help keep these cells calm and modulated, which is why some people with Hashimoto's notice that their brain fog greatly improves once they're given thyroid hormones.
Another common symptom for people with Hashimoto's is fatigue that, in many cases, is being caused by the same brain inflammation. When these people perform activities that require mental activity, such as reading or driving for long periods of time, they get tired. And even after they start taking thyroid hormones, they may continue to have these symptoms. Their brain has less endurance, so they feel worn out when they use their brain for extended periods of time.
If you feel tired when you read, drive or have long conversations, this is brain-based fatigue, but you can't get your brain's endurance back unless you support it. At this point, it's not just a thyroid hormone problem anymore.
Both the inflammation and subsequent fatigue may be due to an autoimmune response, and things that trigger your immune system may also trigger your brain inflammation and neurodegeneration. Two of the main suspects are gluten and a leaky gut; together they equal a leaky brain and brain inflammation.
Microglial cells attack neurons after being stimulated by foreign particles. Zonulin, a protein found in connection with gluten consumption, is linked to a leaky gut (intestinal permeability)—which commonly leads to antibody reactions to foods that, in turn, lead to sensitivities, allergies and eventually conditions like Hashimoto's.
There's a direct link between inflammation in the gut (commonly generated by irritants like gluten), microglial activation (which results when these foreign compounds enter the bloodstream) and brain degeneration.
Dairy has a very similar protein structure to myelin, which envelops the nerves and neurons in the brain. If your immune system attacks dairy, it can also attack your brain, so if you have a leaky gut, you may also have a leaky brain. These same proteins are found in the blood-brain barrier (BBB). When gluten and other proteins and foreign matter get into the bloodstream, they may well end up in your brain.
Gluten has also been linked to the destruction of cerebellar tissue and is known to cause ataxia, or the loss of control of physical/muscle movements. In fact, it's been suggested that a gluten-free diet might help to treat gluten ataxia.1
To improve brain fog, you must reduce brain inflammation and heal the barrier systems because, when things enter the brain that shouldn't, the microglia respond. If that response is severe, there may be collateral damage to the surrounding tissue.
Microglial cells also make up part of the BBB, which is a thin membrane that lines the brain and allows only tiny, essential substances to pass through. The BBB is important for keeping foreign invaders like viruses, bacteria and environmental toxins out of the brain.
Unfortunately, according to Dr Datis Kharrazian, a research fellow at Harvard Medical School and the Department of Neurology at Massachusetts General Hospital, the BBB can develop leaks for a variety of reasons,2 including poor blood sugar control (particularly insulin resistance), chronic stress, chronic inflammation, poor gut health, poor diet with unhealthy fats and unchecked autoimmune activity such as Hashimoto's disease. Alcohol use and high homocysteine levels are also recognized factors.
Research has also shown that gluten can lead to damage to the cerebellum (the Purkinje cells, in particular) through molecular mimicry (proteins on the surface of these cells resemble gluten proteins in structure).3
Hypothyroidism and Hashimoto's can also lead to deficiencies in important neurotransmitters, specifically, serotonin, dopamine, acetylcholine and GABA. A neurotransmitter is a compound released from a nerve terminal. When an electrical impulse travels to the end of a nerve cell, it stimulates the cell terminal to secrete a chemical signal into the spaces between nerve cells called 'synapses.'
These signaling chemicals allow us to have feelings, emotions, passions and instincts. But with hypothyroidism, we can easily become deficient in these chemicals, allowing our emotions to bounce all over the map. As already mentioned, depression and anxiety are commonly seen in Hashimoto's patients. The reason for these feelings is because of this connection between thyroid hormone and these neurotransmitters.
Role of neurotransmitters
Too little serotonin can lead to feelings of sadness, rage and joylessness, or you may just feel like giving up, as it makes you less resilient. Serotonin is used as a messenger to release thyroid-stimulating hormone (TSH), and it modulates the production of T3 within cells via an enzyme called '5-alpha-deiodinase,' which may actually influence the rate of T3 conversion.
It works the other way too. Thyroid hormone has a direct effect on the amount of serotonin in your body. If you have too little thyroid hormone, the synthesis of serotonin is slowed. This is one reason why some people with functional hypothyroidism often feel depressed.
In addition, too little dopamine—the reward and pleasure molecule—can lead to self-destructive thoughts and feelings of isolation, anger and irritability. Not enough dopamine makes you feel like "Who cares?"as there's no reward.
So, with serotonin deficiency, you can't find joy. With dopamine deficiency, you can find joy, but you don't see the point to it.
Thyroid hormones play an important role in the release of dopamine. Studies have shown that reduced dopamine can actually raise TSH. This is yet another reason why testing for TSH and other thyroid hormones in isolation is sometimes not reliable for determining how well your thyroid is functioning.
Acetylcholine is another very important neurotransmitter, as it's involved in learning and memory. Too little acetylcholine can cause memory issues, slow recall, and cause difficulties in calculating numbers and mental focus. When you're hypothyroid, your brain uses acetylcholine to make up for insufficient amounts of thyroid hormone. T3 has been found to directly stimulate acetylcholine.
Finally, too little GABA (gamma-aminobutyric acid) can make you feel anxious, panicky and restless. It's a calming agent, and too little of it also affects how much TSH, as well as the thyroid hormones stimulated by TSH, is released. And thyroid hormones keep GABA in your system after it's released and cause more of it to be released too.
Preventing brain degeneration
Start by addressing what caused a leaky BBB if you want to restore brain integrity. This can best be achieved with what's referred to as the 'Autoimmune Paleo Diet,' a strict ancestral-type diet, which determines whether foods other than gluten, such as dairy or eggs, are provoking your immune system.
Initially, eliminate all processed foods containing sugar, as well as gluten, dairy, soy, seeds, nuts, beans, other grains, nightshades (tomatoes, eggplants, peppers, white potatoes) and many common medications (like antacids and nonsteroidal anti-inflammatory drugs, or NSAIDs). Sometimes nuts are a problem, but steer clear especially of gluten, dairy and soy, as all three can aggravate autoimmunity, increase thyroid tissue destruction and decrease the availability of thyroid hormone in your body.
The Autoimmune Paleo Diet helps to reset brain inflammation and autoimmune thyroid issues because it:
• eliminates many foods that cause problems in the digestive tract
• helps reset your body from sugar-burner/sugar-addict mode to fat-burning mode
• allows the body to repair and rebuild your digestive tract
• can potentially and dramatically boost the results of supplements and medications because it also improves nutrient uptake and utilization.
So, after eliminating all these foods and letting the body repair and rebuild, you can then reintroduce these foods slowly and systematically to identify which are triggers of immune reactions. It is better to reintroduce one food at a time for three days and then keep track of what happens (see the WDDTY July 2017 cover story for more information on Dr Joseph Mercola's fat-burning Paleo-style diet).
Certain foods and supplements can also heal a leaky brain, reduce brain inflammation and increase blood flow to the brain. What's more, the brain's neurotransmitters can all be replenished by consuming the raw materials needed to help your body make more when you're deficient.
Paula, a 45-year-old patient of mine, had a history of serious gastrointestinal problems: a motility test revealed a leaky gut and other intestinal issues. She also often experienced extreme fatigue after meals, and her thyroid medication wasn't controlling her fluctuating thyroid hormone levels.
By strictly following the Autoimmune Paleo Diet, removing foods causing her gut problems and taking certain supplements to detoxify her liver and repair her gut lining and intestinal ecosystem, Paula's thyroid became regulated and her fatigue disappeared as well.
Neurotransmitter symptoms, the key symptoms
Serotonin deficiency: loss of pleasure in hobbies and interests; feeling overwhelmed when managing thoughts; feelings of inner rage or unprovoked anger, paranoia or sadness for no reason; loss of enjoyment in favorite activities, favorite foods, friendships and relationships; and feelings of susceptibility to pain
Dopamine deficiency: feeling like 'What's the point? There's nothing in this for me'; feelings of worthlessness and hopelessness; self-destructive thoughts; inability to handle stress (or getting angry and aggressive when stressed); desire to keep away from others; unexplained lack of concern for family and friends; inability to finish tasks; and feelings of anger for minor reasons
Acetylcholine deficiency: memory issues (especially short-term memories); decrease in visual (shapes and images) and verbal memory; memory lapses; difficulty calculating numbers; difficulty recognizing objects and faces; and slow mental recall
GABA deficiency: feelings of nervousness or panic for no reason; feelings of dread or 'knots' in the stomach; feelings of being overwhelmed for no reason; inability to turn off the mind when relaxing; disorganized attention; worrying over things never thought about before; and feelings of inner tension and excitability
Special thyroid boosters
Consume foods (or take supplements) rich in B-complex vitamins to promote proper energy generation and use:
Vitamin B1—rice bran, sunflower seeds, pinto beans, peas, lentils, almonds, turnip greens, collard greens, kale, asparagus
Vitamin B2—salmon, trout, cod, mackerel, perch, oysters, mushrooms, almonds, hijiki seaweed
Vitamin B3—rice bran, red peppers, wild rice, kelp, sesame seeds, peaches, brown rice, mushrooms, barley, almonds, apricots
Vitamin B5 (pantothenic acid)—beef, chicken, salmon, mackerel, sardines, barley, rice, avocados, plums, raisins, almonds, dates
Vitamin B6—bananas, barley, brewer's yeast, molasses, brown rice, liver, beef, cabbage, carrots, potatoes, yams
Vitamin B12—beef liver, beef kidney, ham, sole, scallops, eggs, oats, pickles, amazake (fermented rice drink), seaweed, Spirulina, Chlorella, brewer's yeast
Vitamin B9 (folic acid)—liver, asparagus, lima beans, spinach, Swiss chard, kale, cabbage, corn.
Excerpted from How to Heal Hashimoto's by Marc Ryan (Hay House, 2017)