She had always been a happy, joyful, and energetic person. But lately, she found herself exhausted, irritable, and overwhelmed by anxiety. Simple tasks seemed monumental. She blamed stress, but she knew something was wrong inside her body. After several doctor visits, a blood test finally revealed the culprit—her thyroid hormones and the behavioral changes that they cause.
Her story is something we hear every other day. Thyroid hormones are tiny yet powerful chemicals produced by the thyroid gland. These hormones regulate our metabolism and energy levels. When thyroid hormones are out of balance, they can lead to significant behavioral changes. These changes often look similar to mental health disorders, making them challenging to diagnose. In this article, we will understand how behavioral changes occur because of thyroid imbalance.
Let’s first understand thyroid hormones and the imbalances associated with them.
Contents
Understanding Thyroid Gland and Hormones
Image: Thyroid Gland
An essential endocrine (hormone-producing) gland is the thyroid gland. It has a significant impact on both our growth and development. It plays an important role in the chemical reactions that make up our metabolism. The thyroid gland is under the voice box at the front of the neck. It looks like a butterfly, with the two lobes on either side resting against and encircling the trachea. The thyroid gland secretes three hormones.
- Triiodothyronine or T3.
- Thyroxine, or T4, or tetraiodothyronine.
- Calcitonin
Image: Thyroid hormones
Only T3 and T4 are considered to be appropriate thyroid hormones. They are produced in the thyroid’s follicular epithelial cells.
Release of Thyroid Hormones and Their Function:
A feedback loop regulates the synthesis and release of thyroid hormones, triiodothyronine (T3) and thyroxine (T4).
The area of the brain that regulates bodily temperature, heart rate, blood pressure, and digestion is called the hypothalamus.
The pituitary gland is a tiny, pea-sized gland that is situated beneath the hypothalamus at the base of the brain. It produces eight different hormones.
Release of thyroid hormones
A network of nerves and blood vessels links your hypothalamus and pituitary gland. Your hypothalamus sends signals to your pituitary gland to release specific hormones. The hypothalamus releases thyroid-releasing hormone (TRH) to initiate the feedback loop, which causes your pituitary gland to create and release thyroid-stimulating hormone. Your thyroid then produces T4 and T3 as a result of TSH. About 80% of the hormones your thyroid releases in response to TSH stimulation are T4 and 20% T3. To produce T4 and T3, your thyroid also needs enough iodine, a mineral found in food.
Thyroxine (T4) released into your bloodstream by your thyroid is converted to triiodothyronine (T3) by certain cells in your body through a process known as de-iodination. This is because cells with receptors for thyroid hormone are more adept at using T3 than T4. As a result, T3 is usually thought to be the active form of thyroid hormone, and T4 is the inactive type.
Image: Activation of thyroid hormones
Image source: https://www.nature.com/articles/boneres201311/figures/1
Functions of Thyroid Hormones
Thyroid hormone (T3 and T4) influences every cell and organ in your body through:
- It controls the rate at which your body consumes calories (energy). The metabolic rate determines whether you lose or gain weight.
- It increases or slows your heart rate.
- Raise or reduce your body temperature.
- Influencing the rate at which food passes through your digestive tract.
- Affects brain development.
- Controlling how your muscles contract.
- Controlling the rate at which your body replaces dying cells (a normal process) to maintain skin and bone health.
Hypothyroidism vs. Hyperthyroidism
Hypothyroidism, or underactive thyroid, occurs when the thyroid gland does not produce enough thyroid hormones to meet your body’s requirements.
Hyperthyroidism, or overactive thyroid, occurs when the thyroid gland produces more thyroid hormones than the body requires.
Hypothyroidism and behavioral changes
- Depression
The link between hypothyroidism and depression is well known. Research shows somatostatin and serotonin alter the hypothalamus-pituitary-thyroid axis, linking hypothyroidism to depression. Multiple studies found that undiagnosed and hypothyroidism individuals are more likely to develop depression.
- Anxiety and panic attacks
Hypothyroidism can induce physical changes and increased sensitivity to how your body feels, resulting in health anxiety and panic attacks. It can also produce rapid and odd cognitive patterns, which can lead to health anxiety.
- Mood swings and fatigue
Hypothyroidism can cause mood swings, depression, and a short temper. Psychological symptoms can appear before physical symptoms and lead to a late diagnosis. Hypothyroidism can also cause fatigue, sluggishness, and tiredness. People with hypothyroidism may also sleep too much.
Hyperthyroidism and behavioral changes
- Anxiety and panic attacks
Hyperthyroidism can generate anxiety-like symptoms that resemble psychiatric diseases, such as panic attacks and generalized anxiety disorder (GAD). Over 60% of patients with hyperthyroidism suffer from anxiety, compared to 30% with hypothyroidism.
- Bipolar Affective Disorders
Symptoms of hyperthyroidism (overactive thyroid) include restlessness, irritability, anxiety, panic attacks, and mania. These symptoms may be related to a medical condition, such as bipolar disorder, or they may be just thyroid-related.
- Mood swings
People with hyperthyroidism may suffer a wide range of emotional and mood disturbances. Typically, the more overactive your thyroid is, the more dramatic your mood swings will be. Emotional transformations include restless feelings, unexpected nervousness, and unusual irritation.
The bidirectional relationship between thyroid hormones and behavioral changes
Thyroid hormones and behavioral changes are closely related and are complex, with each influencing the other. Low thyroid hormone levels (hypothyroidism) often lead to depressive symptoms, while excessive levels (hyperthyroidism) can cause anxiety and irritability. Conversely, stress and mood disorders can disrupt thyroid function, exacerbating these conditions. Understanding this bidirectional relationship is crucial for effective diagnosis and treatment, as addressing thyroid and mental health can lead to better patient outcomes.
References
- https://www.ncbi.nlm.nih.gov/books/NBK279388/
- https://www.endocrine.org/patient-engagement/endocrine-library/hormones-and-endocrine-function/thyroid-and-parathyroid-hormones
- https://my.clevelandclinic.org/health/articles/22391-thyroid-hormone
- https://www.ncbi.nlm.nih.gov/books/NBK285549/
- https://www.stlukeshealth.org/resources/thyroid-disease-behind-your-mood-swings
Written By: Kamni