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Author Topic: The effects of Hashimoto’s and hypothyroidism on brain health  (Read 16539 times)

Offline MiraD

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Do you need to take the Leaky Brain Challenge? Read on to find out.

The most disturbing thing I see in regards to Hashimoto’s is that although people’s TSH may be managed with thyroid hormones, their immune dysregulation goes unchecked. This leaves other areas of the body vulnerable to attack, the most profound being the brain.

There are three ways Hashimoto’s can affect the brain. First, many people with Hashimoto’s also have an autoimmune attack against their nervous system. On a blood test this can be identified by positive antibodies to neurological tissue.  Second, unrelated to an autoimmune attack against the nervous system, the inflammatory response generated by Hashimoto’s can activate the brain’s immune system, hence promoting inflammation in the brain. Third, Hashimoto’s can lead to low thyroid hormones, which are necessary to dampen the brain inflammation caused by the previous two factors.

Depression, fatigue, and brain fog

It’s important to know that we all experience brain degeneration on an ongoing basis. A more common term for accelerated brain degeneration is simply known as aging. The trick is to prevent the brain from degenerating any faster than it has to.

Unfortunately, it is very common to see advanced brain degeneration in long-term, unresolved Hashimoto’s cases, with the most common symptoms being depression (from decreased firing of the frontal cortex), fatigue (from brain fatigue due to neurodegeneration), and brain fog (from brain inflammation).

True, these are also symptoms of hypothyroidism, but in some cases, particularly when the condition is long standing or still persistent despite successful management of thyroid levels, the impact of an unresolved thyroid condition on the brain should be investigated.

How Hashimoto’s affects the brain’s immune system

The brain is made up of two types of cells: neurons and microglia cells. Neurons are responsible for communication within the brain and everything we associate with brain activity, such as our intelligence, emotions, and the ability to automatically breathe, digest or maintain a heartbeat.

The microglia cells are the brain’s immune cells. It’s their job to react to foreign invaders, clean up debris and plaque, and dissolve dead neurons. The microgia are necessary for optimal neuronal communication and healthy brain function.

Although microglial cells function as the brain’s immune system, they are unlike the immune system in the rest of the body. When a virus or bacteria invades your body, the body’s immune system orchestrates a comlex and multi-faceted response, as described briefly in Chapter Three of my book. For instance, once an antigen (a foreign invader) is successfully dispatched, the immune system’s T-suppressor cells call off the attack and send the troops home.

Not so with the brain’s immune system. If an antigen makes its way into the brain, there is no complex orchestration, but rather an all-out assault by the brain’s microglial cells on the invader and, as a consequence, inflammation and degeneration of surrounding brain tissue. What’s worse is that there are no T-suppressor cells to call off the attack, and the glial cells, in their unrestrained assault, create brain inflammation and chew up brain tissue in a degenerative cascade.

Hashimoto’s is a double whammy for the brain

Unfortunately, Hashimoto’s activates microglia cells in two ways.  First, thyroid hormones are integral to brain health, and Hashimoto’s can lead to low thyroid hormone status. Thyroid hormones dampen overactivity of the microglial cells, thus preventing or slowing down this cascade that causes inflammation and degeneration in the brain.(1-8)

Second, the inflammatory response caused by Hashimoto’s increases the activity of the brain’s microglia cells, hence promoting brain inflammation.(9)

So failing to address the autoimmune attacks of Hashimoto’s is a double whammy on the brain — the inflammation caused by Hashimoto’s increases microglial activity, while low thyroid hormone status fails to adequately dampen the microglial cells.

The effect of Hashimoto’s on the blood-brain barrier

The microglia cells not only make up more than half of the total mass of the brain, but they also make up the blood-brain barrier, a thin barrier that lines the brain and allows necessary, nano-sized substances to pass through. The blood-brain barrier is important for keeping antigens (foreign invaders, such as viruses or bacteria) and environmental toxins out of the brain.

Unfortunately, the blood-brain barrier can develop “leaks” for a variety of reasons, including poor blood-sugar stability (particularly insulin resistance),(10) chronic stress,(11) chronic inflammation,(12) poor gut health, poor diet with unhealthy fats,(13) and unchecked autoimmune activity, such as Hashimoto’s disease (alcohol and high homocysteine are other recognized factors(14-16)). If you are familiar with leaky gut, as discussed in the book, then you’ll understand leaky brain, as both the gut and the brain are immune barriers vulnerable to the same problems.

When the blood-brain barrier develops leaks, bad guys get in, the microglial cells go nuts, and a whole lot of brain tissue gets chewed up. This creates inflammation, which in felt in some as “brain fog,” and leads to accelerated brain degeneration.

The Leaky Brain Challenge

How do you know if your blood-brain barrier is leaky? A simple and easy way to find out is to do Blood-Brain Barrier Challenge. To do this, simply take 1000 mg of straight GABA (not GABA precursors such as theanine).

GABA is a neurotransmitter synthesized in the brain and is responsible for calming or inhibiting over activity. Although some companies sell GABA supplements, the reality is the GABA molecule is too large to pass through an intact blood-brain barrier. The fact that this supplement sells so well is a testament to the integrity of the average American’s blood-brain barrier.

So, if several hours after taking 1000 mg of GABA, you feel calm, relaxed or sleepy, you know that GABA, a molecule too large to pass through the blood-brain barrier, has nevertheless made it into your brain and is performing its calming duties. This means your blood-brain barrier has become compromised and your brain is highly susceptible to the immune rampages I discussed above.

Some people, instead of feeling relaxed, will find GABA makes them feel more anxious or jittery. There are other reasons for this that will be discussed in my next book, however any reaction at all indicates a leaky brain barrier.

If you felt no change after taking GABA, that is a good sign that your blood-brain barrier is intact and functioning well. (For accurate results, be sure to take this test during the day and not at bedtime.)

What to do about a leaky brain barrier

Addressing the areas that helped cause a permeable blood-brain barrier is the best place to start if you want to restore integrity. First make sure your diet is strictly void of gluten. Then do an Elimination/Provocation diet, as explained in my book, to determine whether other foods, such as dairy or eggs, are also provoking the immune system.

Continue on with the other strategies explained in the book: Balancing blood sugar, addressing gut health and gut infections, and supporting adrenal health so your adrenal hormones are neither too high or too low. All of these will help quench inflammation, a notorious saboteur of brain health. Also, ask your practitioner about the supplements I have created specifically for blood-brain barrier integrity, brain inflammation and increased blood flow to the brain (which will be discussed in my next book). Other strategies include enhancing the liver’s methylation pathway (Chapter Eight of the thyroid book) and supplementing with alpha-lipoic acid.

Modulating your autoimmune disease is a vital step to protecting the integrity of your blood-brain barrier and the health of your brain. The longer Hashimoto’s or any autoimmune disease goes on unchecked, the more vulnerable your brain is to autoimmune disease, degeneration, and inflammation.


1 Pumirat J. Prog Neurobiol. 1992;39:281-294.

2 Limr FRS, et al. J Endocrinol. 1997;154:161-175.

3 Gomes FCA, et al. Adv Exp Med Biol. 1997;429:99-108.

4 Mallet M, et al. Adv Exp Med Biol. 1997;429:99-108.

5 Dobbertin A, et al. J Neuroscie. 1997;17:5305-5315.

6 Bernal J, et al. Thyroid hormones and brain development. Eur J Endocrinol;133:390-398.

7 Calza L, et al. Thyroid hormone-induced plasticity in the adult rat brain.  Brain Res Bull. 1997;44(4):549-57.

8 Flavin RSL, et al. Regulation of microglial development: A novel role for thyroid hormones. The Journal of Neuroscience. 2001;21(6):2028-2038.

9 Flavin RSL, et al. Regulation of microglial development: A novel role for thyroid hormones. The Journal of Neuroscience. 2001;21(6):2028-2038

10 Kamada H et al. Influence of hyperglycemia on oxidative stress and matrix metalloproteinase-9 activation after focal cerebral ischemia/reperfusion in rats. Stroke. 2007;38:1022-1049.

11 Espositie, P, et al. Acute stress increases permeability of the blood-brain barrier through activation of brain mast cells. Brain Research. 2001;888(1):117-127.

12 Haroh J, et al. Oxidative stress activates protein tyrosine kinase and matrix metalloproteinases leading to blood-brain barrier dysfunction. J neurochem. 2007;22(1).

13 Jali C, et al. Cyclooxygenase inhibition limits blood-brain barrier diruption following intracerebral injection of tumor necrosis factor-alpha in the rat. JPET. 2007;323(2):488-498.

14 Haorah J, et al. Alcohol0induced oxidative stress in brain endothelial cells causes blood-brain barrier dysfunction. Journal of Leukocyte Biology. 2005;78:1223-1232.

15 Atul F, et al. Elevated levels of homocysteine compromise blood-brain barrier integrity in mice. Blood. 2005.

16 Homocysteine attenuates blood-brain barrier function by inducing oxidative stress and the junctional proteins. FASEB. 2008;22:734-7.

Offline JudithSil

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Re: The effects of Hashimoto’s and hypothyroidism on brain health
« Reply #1 on: March 04, 2010, 08:26:54 AM »
Thank you for this. I have had MS for a decade and am about to undergo testing for Hashimoto's,  as well as a Fine Needle Biopsy for thyroid cancer, given various suspicious symptoms plus a thyroid nodule visible on my last MRI (which included the cervical spine & thus happened to show the thyroid). 

I don't yet know whether I really have thyroid issues, nor can I know the exact connection between the MS & thyroid issues (which came first? etc.). But over the years I have been doing some of the neuroprotective things you recommend - I find lipoic acid really seems to help the fog & confusion - & will look into the others, both for myself & future clients.