Could Your Thyroid Be the Cause of Your Depression?

People with thyroid disorders might be more likely to struggle with symptoms of depression. Many people who have thyroid disorders often report other negative health problems. This can include mood and depression symptoms. Is there a connection between thyroid disorders and depression?

Key takeaways:
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    People with thyroid disorders may be more likely to struggle with symptoms of depression.
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    People with thyroid disorders have been found to be more likely to have depression than the general population.
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    People with a known history of hypothyroidism have a greater chance of developing depression during their lifetime.
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    Treatment for people suspected of depression related to thyroid disorder begins with treating the thyroid.

An overview of the thyroid and depression

The thyroid is a gland that releases hormones that control several body functions. These hormones control the heart, breathing, body temperature, and many other bodily functions. Thyroid hormones include Thyroxine (T4), Triiodothyronine (T3), and Calcitonin.

If these hormone levels are abnormal, the body's systems won’t work properly. This can cause symptoms in some systems alerting to a problem, but there may not be. Symptoms may be so gradual they are not noticed. The body's systems slow down, like in the case of hypothyroidism. Hypothyroidism is defined as a deficiency of thyroid hormone. In areas of adequate iodine uptake such as the United States, the most common cause of hypothyroidism is autoimmune thyroid disease or Hashimoto disease. Hashimoto's disease is more prevalent in women and increases with age.

Hyperthyroidism is the opposite situation. The thyroid releases too much hormone into the bloodstream, and the body starts to speed up. This can occur suddenly and the symptoms can begin without warning.

Signs and symptoms of hypothyroidism may include fatigue, lethargy or depression. Depression is a common mental health illness that causes daily or nearly everyday feelings of sadness, helplessness, worthlessness, loss of interest, decreased energy, or even suicidal thoughts.

Symptoms last longer than two weeks and everyone may not experience all symptoms. Some people may have only a few symptoms, while others may have several. Symptoms can also range from mild to severe.

Hypothyroidism is generally diagnosed by a blood test measuring TSH (thyroid stimulating hormone) level. Treatment is thyroid hormone replacement therapy and rarely surgery.

It is important to understand that although hypothyroidism may be associated with symptoms of depression, the vast majority of patients with depression do not have clinical evidence of thyroid dysfunction.

Is there a connection between the thyroid and depression?

Over the years, studies have found that symptoms of depression and thyroid disorders are similar. Symptoms of depression often appear in people whose thyroid hormone levels are not at healthy levels. This is particularly true in hypothyroidism.

People with hypothyroidism often have symptoms of depression, decreased attention, or slower reactions. People with hyperthyroidism often experience symptoms of anxiety, inability to concentrate, or exaggerated moods.

How does the thyroid affect depression?

The thyroid has a direct effect on mood which can include depression and anxiety. The severity of the depression can vary depending on the severity of the thyroid disorder. The connection between the two comes through the hypothalamic-pituitary-thyroid axis.

The hypothalamic-pituitary-thyroid (HPT) axis is a loop that cycles feedback between the hypothalamus and the pituitary gland overseeing thyroid hormone levels. When thyroid hormone levels are high, the HPT axis responds, telling the pituitary gland not to release thyroid stimulating hormone (TSH) so that T3 levels can decrease.

When thyroid levels are low, the opposite happens. The HPT axis responds by telling the pituitary gland to release more TSH. This prompts the thyroid to increase how much T3 is released. This helps bring the thyroid hormone level to normal.

However, when thyroid levels are abnormal, it throws the loop out of balance. This alters hormone levels throughout the body, affecting mood and other bodily functions.

Treatment goals for hypothyroidism include reversing clinical progression and correcting any metabolic abnormalities such as TSH and thyroid hormone levels, specifically free thyroxine (T4).

Who might be affected?

Thyroid disorders can affect anyone at any age but are much more likely to affect women between ages 20 and 40. However, as people age, that risk increases. People over age 60 have an increased chance of developing a thyroid disorder. The American Thyroid Association recommends screening at the age of 35 years and then every 5 years thereafter. High-risk patients include pregnant women, patients with type 1 diabetes or other autoimmune diseases, or patients who have undergone neck irradiation such as for cancer treatment.

Depression can also occur at any age but is more likely to happen to adults near midlife or older. This is particularly true for adults diagnosed with health problems. Diseases and medications can also impact mood and mental health. These factors increase the risk of depression.

People with thyroid disorders are more likely to have depression than the general population. Studies show that patients with a known history of hypothyroidism have a greater chance of developing depression during their lifetime.

On the contrary

As research into HPT, thyroid levels, and depression increases, there are more questions about whether the thyroid directly causes depression or if it’s more of a coincidence. Some studies suggest that these theories are being debunked. Symptoms of depression and thyroid disorders can be very similar. Some researchers believe they may simply be found together by chance.

The idea that thyroid disorders and depression are not always linked comes from proof that when treating the thyroid disorder, the depression does not always improve. In the same respect, not all patients with thyroid disorders suffer from mood changes. Also, the opposite is true. Patients who struggle with mood disorders and depression do not necessarily have abnormal thyroids.

While it remains true that there is a link between the two, it is not true in all cases. It is something to look at when assessing symptoms of depression and thyroid disorder. This is especially true when symptoms present in someone with both problems.

Is it the thyroid or depression?

Your healthcare provider can help determine if you have symptoms of one, the other, or both. If you have symptoms of a thyroid disorder, your provider will complete a physical exam to assess the thyroid to feel for enlargement or nodules. They will order bloodwork to check your T3, T4, and TSH levels. This will provide the best information for diagnosis.

If you are suffering from symptoms of depression, be sure to discuss this with your healthcare provider. It will be important to seek appropriate treatment, regardless of the cause. You will want to note whether or not symptoms improve if thyroid treatment is recommended.

When depression may be related to thyroid disorder, treatment begins with treating the thyroid with replacement therapy. Patients receiving treatment for abnormal thyroid levels notice an improvement in depression symptoms. This isn’t always true for the opposite. Patients treated for depression with thyroid medications did not always find improvement.

In conclusion, multiple studies have been conducted in recent decades to determine whether depression is related to thyroid disorders. People who have thyroid disorders often report symptoms of depression. Some people also report improvement of symptoms with treatment of thyroid disorder. Some patients with depression even reported improved symptoms after treatment with thyroid medications. But, some recent studies suggest these health issues are simply coincidental.

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