An underactive thyroid and depression can both affect a person’s mood during their daily life. There is also increasing evidence of links between these two conditions.
Hypothyroidism is a condition where the thyroid produces too few hormones. Possible causes of the condition include autoimmune disease, removal of the thyroid, or radiation treatment.
The thyroid is a small gland in the neck, just in front of the throat. The gland produces hormones that are essential for converting food into energy and supporting growth.
Problems with the thyroid can have many consequences, including causing symptoms of depression.
There may be some links between these two conditions, but it is unlikely that depression causes hypothyroidism.
There is research, however, to suggest that hypothyroidism may lead to depression in some people.
It is also possible that medications for mood disorders that interfere with people’s mental health can affect their thyroid functioning.
Lithium is a common treatment or bipolar disorder.
Lithium affects the thyroid and prevents the production of T3 and T4 hormones. People taking lithium are more likely to develop hypothyroidism.
However, some people with bipolar disorder are more likely to have hypothyroidism regardless of lithium treatment.
An older study from 2002 found that
SSRIs can reduce T4 hormone levels by
When the thyroid is not working as it should, some people develop mental health problems. If the thyroid produces too many or too few hormones, it can cause mood changes.
Hypothyroidism can affect the
People with severe hypothyroidism may experience symptoms of depression or dementia, what some term pseudodementia.
Hormone changes in the
These hormone changes interrupt the movement of chemical signals in the brain. They mostly affect the hippocampus, a part of the brain important for learning and memory.
The changes can cause
- behavioral changes
- difficulty learning new things
- memory problems
- speaking difficulties
Hypothyroidism has many symptoms. The earliest symptoms are psychiatric, affecting how the brain works.
These symptoms account for
- memory lapses
- difficulty concentrating
- speech problems
People with hypothyroidism and anxiety may respond to
But L-T4 therapy is not always useful for anxiety symptoms. In one study, the use of L-T4 therapy
Hypothyroidism and depression can produce similar symptoms. For example, both can cause changes in mood.
There may be a link between hypothyroidism and depression. It is more likely that hypothyroidism causes symptoms of depression, rather than depression leading to hypothyroidism.
For example, hypothyroidism can affect hormone production and disrupt chemical signaling in the brain, leading to depression.
There is a link between hypothyroidism and the use of some medications for depression and bipolar disorder. For example, lithium affects hormone production by the thyroid, which might lead to hypothyroidism.
Some SSRIs also affect thyroid production. But changing to a different medication may reverse hypothyroidism.
Hypothyroidism may also cause anxiety symptoms, although, the evidence for this is weak. L-T4 therapy for hypothyroidism and anxiety could reduce symptoms in some people but might worsen them in others.