What are the links between thyroid health and mental health?

The messenger molecules that are released from the thyroid are called thyroid hormones. These hormones are thyroxine (T4) and triiodothyronine (T3) and they act on cells all around the body by interacting with thyroid hormone receptors. And this is where the strong link to mental health comes in. The brain has some of the highest expression of these thyroid hormone receptors and neurons are often more sensitive to thyroid abnormalities than other cells (1).

Thyroid health and neurological effects in infants and children
When the brain is still developing, the actions of thyroid hormones are very important. This is because certain thyroid hormone actions must occur during specific time windows. If thyroid abnormalities occur during brain development, they may lead to irreversible brain damage. The extent of this damage depends on both the severity of thyroid problems, as well as the specific onset and duration of the thyroid problems (2).

This potentially serious impact of thyroid abnormalities is why normal thyroid function is critical during pregnancy. For the first trimester, a fetus is completely dependent on thyroid hormones from the mother (passed through the placenta). At around 12 weeks, the fetus starts to make its own thyroid hormones, but it is still reliant on maternal thyroid hormones until 18–20 weeks of pregnancy (3).

Thyroid health and mental health in adults
Most thyroid-associated mental health problems in adults are reversible with proper treatment, unlike the sometimes-irreversible brain damage seen in infants and children (2). However, that doesn’t mean that thyroid-associated mental health problems in adults should be ignored.

Hypothyroidism (underactive thyroid) is associated with:

• Memory impairment
• Bipolar affective disorders
• Depression
• Mood disorders
• Dementia
• Confusion
• Personality changes
• Loss of cognitive function

Hyperthyroidism (overactive thyroid) is associated with:

• Anxiety
• Irritability
• Mood disorders
• Dementia
• Confusion
• Personality changes

Of course, the lists above are only covering the thyroid dysfunction symptoms that are linked to mental health. Thyroid abnormalities can also cause a range of other symptoms, including:

• Puffy eyes and face
• Heart rate changes (slower for hypothyroidism, faster for hyperthyroidism)
• Temperature changes (feeling colder for hypothyroidism and excessive sweating for hyperthyroidism
• Weight changes (gain for hypothyroidism, loss for hyperthyroidism)
• Fertility issues

Thyroid testing
If you are experiencing symptoms that could be associated with abnormal thyroid function, don’t hesitate to get tested. We offer a range of tests from just a simple self-collected finger-prick. Take our simple Thyroid Stimulating Hormone (TSH) Test for TSH alone, our Thyroid Health Panel to also include T4 and T3 along with TSH, or opt for the Thyroid Health, Complete Panel to also include Anti-Tg and Anti-TPO.

TSH is the thyroid-stimulating hormone, which is produced in the pituitary gland and signals for the thyroid to produce thyroid hormones. TSH is commonly the first molecule measured when investigating thyroid health. Read our previous article here for more information about TSH.

T4 and T3 are the two hormones produced by the thyroid.

Anti-Tg and Anti-TPO are antibodies to proteins produced by the thyroid gland. Elevated levels of these antibodies signal that the body’s own immune system is targeting and harming the thyroid, which is what occurs in some autoimmune disorders.

References:
1. Rege S. (Updated April 2021) 15 little known things about your thyroid that can affect your mental health. Psych Scene Hub.
2. Bernal J. Thyroid hormones in brain development and function. Endotext [Internet].
3. Thyroid disease & pregnancy. (Reviewed Dec 2017). NIH, National Institute of Diabetes and Digestive and Kidney Diseases.