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Most of us are aware that mental health issues like depression, anxiety, and brain fog often go along with Hashimoto’s thyroiditis and hypothyroidism. But these are just a few of many neuropsychiatric disorders and symptoms associated with autoimmune Hashimoto’s disease and an underactive thyroid.

Research shows that hypothyroidism actually changes your brain’s structure and function. Specifically, hypothyroidism can reduce the size of the hippocampus, the area of the brain that controls emotion, memory, and the autonomic nervous system. Patients with hypothyroidism also experience reduced blood flow in the brain, affecting areas of the brain that help control attention, processing, and memory. There’s also evidence that inflammation from autoimmune Hashimoto’s can occur in the brain.

These structural and functional changes – as well as cerebral inflammation -- can result in psychiatric symptoms and conditions, mood disorders, and cognitive dysfunction, ranging from mild to severe. Ahead, a review of related neuropsychiatric issues associated with Hashimoto’s and hypothyroidism.
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Your Guide To The Genetics Of Thyroid Function

Knowing your risk for thyroid disease can help you stay in front of complications. Learn in this guide how genes impact your risk for hypothyroidism.

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Mood disorders, depression, and anxiety are well-known symptoms in people with hypothyroidism. Typically, the signs and symptoms in hypothyroid patients include sadness, apathy, being easily fatigued, and other depressive symptoms. The severity of the depression loosely correlates with the degree of hypothyroidism. Overt and untreated hypothyroidism with TSH levels above 10 mIU/L is associated with more significant depression. Subclinical hypothyroidism – defined as Free Thyroxine (Free T4 levels) in the normal range and Thyroid Stimulating Hormone (TSH) levels between the upper limit of the reference range, but less than 10 mIU/L – is more often associated with milder depression.

Anxiety is also associated with overt and untreated hypothyroidism, with symptoms that include agitation, insomnia, and nervousness. Hypothyroidism is also associated with a higher rate of anxiety-related affective disorders, including panic disorder, Generalized Anxiety Disorder (GAD), and Obsessive Compulsive Disorder (OCD). Interestingly, among hypothyroid patients, OCD is even more common in those patients who are hypothyroid due to Hashimoto’s thyroiditis.

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It’s not common, but in some cases, overt hypothyroidism can cause a more severe psychiatric disturbance known as “myxedema madness.” In its early stages, myxedema madness symptoms include forgetfulness, problems with concentration, slowed thinking, fatigue, and rapid mood changes. Later, it can progress to psychotic symptoms, including auditory and visual hallucinations, delusions, mania, and suicidal ideation. Myxedema madness usually resolves once a patient becomes euthyroid and has normal thyroid levels.

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Hypothyroidism can cause various types of cognitive impairment. According to research, memory – especially verbal memory – is the most commonly affected cognitive ability.

Some of the other Hashimoto’s- and hypothyroidism-related cognitive symptoms include:

• Slowing of thought and speech
• Decreased attentiveness
• Difficulty with sustained mental exertion
• Difficulty comprehending complex questions
• Difficulty learning new tasks
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Dementia is defined as a group of syndromes characterized by various symptoms, including impaired memory, judgment, reasoning, behavior, and communication skills.

The Mayo Clinic’s extensive list of symptoms of dementia includes “mental decline, confusion in the evening hours, disorientation, inability to speak or understand language, making things up, mental confusion, or inability to recognize common objects, irritability, personality changes, restlessness, lack of restraint, wandering and getting lost, anxiety, mood swings, agitation, depression, hallucination, or paranoia, lack of coordination, falling, memory loss, jumbled speech, and sleep problems.”

According to research published in Neurology in 2022, the risk of developing dementia is higher in older people with hypothyroidism. Specifically, people over 65 with hypothyroidism are around 80% more likely to develop dementia than people the same age with normal thyroid function. This research also showed that the degree of dementia increases as TSH levels increase and Free T3 levels decrease

Another study found, “Every 6 months of elevated TSH increased the risk of dementia by 12%, suggesting that the length of hypothyroidism also influences the risk of dementia.”

Many experts agree that “hypothyroidism is one of the most important causes of potentially reversible dementia.”

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Hashimoto’s encephalopathy (HE) – also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) – is a very rare but often misdiagnosed neuropsychiatric condition that affects women in their 50s and 60s primarily. The clinical symptoms of HE include headaches, personality changes, memory loss, delusional behavior, dementia, seizures, ataxia (poor muscle control and coordination), aphasia (loss of ability to understand or express speech), hallucinations, and coma.

In HE, almost all patients usually have high levels of Thyroid Peroxidase Antibodies (TPOAb), and the majority also have elevated Anti-thyroglobulin Autoantibodies (TGAb). In HE, the symptoms are far more prevalent when TPOAb is higher. Approximately 35% are subclinically hypothyroid, and 20% have overt hypothyroidism. (The remaining HE patients have hyperthyroidism or normal thyroid levels.) A small subset of HE patients has a goiter, an enlarged thyroid.

Diagnosing HE can be challenging, as it’s a diagnosis of exclusion, and other neuropsychiatric conditions need to be ruled out. HE is frequently misdiagnosed as a seizure disorder, stroke, or other neurological diseases. Most HE patients need to work with a neurologist – rather than an endocrinologist – to get an HE diagnosis.

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There’s good news for people with hypothyroidism and neuropsychiatric symptoms. According to the latest research, these symptoms tend to improve – and even resolve completely -- with thyroid hormone replacement treatment.

For example, hypothyroidism-triggered depression, dementia, and many neuropsychiatric and cognitive deficits can be largely reversed with thyroid treatment.

Researchers have reported that deficits in working memory and abnormal functional magnetic resonance imaging (fMRI) results were no longer present after six months of thyroid treatment in most patients.

A caution, however. Even with thyroid hormone replacement treatment, neuropsychiatric symptoms can continue in some patients. Residual symptoms are more common in patients with treatment-resistant depression, genetic mutations associated with severe depression, and those with long-standing dementia.

Experts also point out that patients with subclinical or treated hypothyroidism who continue to have significant neuropsychiatric symptoms after treatment likely have an independent, non-thyroid-related neuropsychiatric illness that needs separate diagnosis and treatment.

The primary treatment for HE/SREAT is corticosteroid drugs to reduce inflammation. In some cases, Intravenous Immunoglobulin (IVIg), immunosuppressant drugs, and plasmapheresis have also been used to treat HE. Thyroid hormone replacement medication is incorporated into treatment when patients are subclinically or overtly hypothyroid.

A 2016 study found that 91% of HE patients experienced at least a 50% improvement – up to complete remission – with steroid treatment. Because HE is treatable – but not curable – an estimated 16% of patients have one or more relapses.

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When you have Hashimoto’s or hypothyroidism, no surefire formula can predict the number and degree of your physical symptoms based on your TSH level. Similarly, your thyroid test results may not track precisely with your mental health, mood, and cognitive symptoms. One patient can be diagnosed with hypothyroidism with an elevated TSH of 50 and report no mental health or cognitive symptoms. Another patient can have a mildly elevated TSH level of 8 and report significant and debilitating challenges.

What is clear, however, is that both subclinical and overt hypothyroidism are known factors contributing to various neuropsychiatric symptoms and conditions. And that means that early diagnosis and treatment, frequent thyroid testing, and careful management of hypothyroidism are all crucial aspects of managing mental health, mood, and cognitive issues.

Paloma’s Complete Thyroid Blood Test Kit makes getting a comprehensive thyroid panel at home easy and affordable. The test kit accurately measures your TSH, Free T4, Free T3, and TPOAb, and returns the results to you securely and quickly.

And, Paloma’s team of thyroid-savvy healthcare providers can provide support at every stage of your hypothyroidism treatment. Paloma’s doctors will help ensure that your treatment plan is effective and your thyroid replacement therapy is optimal, as part of your overall approach to resolving neuropsychiatric challenges.
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Can hypothyroidism cause depression and anxiety?

Yes. Mood disorders, depression, and anxiety are well-known symptoms in people with hypothyroidism, often showing up as sadness, apathy, fatigue, agitation, insomnia, and nervousness. The severity of depression loosely correlates with the degree of hypothyroidism, with untreated hypothyroidism and TSH levels above 10 mIU/L associated with more significant depression. Hypothyroidism is also linked to higher rates of anxiety-related disorders, including panic disorder, generalized anxiety disorder, and OCD, with OCD being even more common among those whose hypothyroidism is caused by Hashimoto's thyroiditis.

What is "myxedema madness"?

Myxedema madness is a rare but severe psychiatric disturbance that can occur with overt hypothyroidism. Early symptoms include forgetfulness, trouble concentrating, slowed thinking, fatigue, and rapid mood changes, which can later progress to psychotic symptoms like hallucinations, delusions, mania, and suicidal ideation. It usually resolves once a patient becomes euthyroid, meaning their thyroid levels return to normal.

Can hypothyroidism affect memory and cognitive function?

Yes, hypothyroidism can cause various types of cognitive impairment, with memory (especially verbal memory) being the most commonly affected ability. Other reported cognitive symptoms include slowed thought and speech, decreased attentiveness, difficulty with sustained mental exertion, trouble comprehending complex questions, and difficulty learning new tasks.

Is there a link between hypothyroidism and dementia?

Research shows that people over 65 with hypothyroidism are around 80% more likely to develop dementia than people the same age with normal thyroid function, and dementia risk increases as TSH levels rise and Free T3 levels fall. One study found that every 6 months of elevated TSH increased dementia risk by 12%. Many experts consider hypothyroidism one of the most important causes of potentially reversible dementia.

Will treating hypothyroidism improve mental health and cognitive symptoms?

For many people, yes. Research shows that neuropsychiatric symptoms, including depression, dementia, and cognitive deficits, tend to improve and can even resolve completely with thyroid hormone replacement treatment. However, some patients continue to have residual symptoms after treatment, particularly those with treatment-resistant depression, genetic mutations associated with severe depression, or long-standing dementia. Patients whose symptoms persist after adequate thyroid treatment may have a separate, non-thyroid-related condition that needs its own diagnosis and treatment.