Hypothyroidism and bipolar disorder: what is the connection?

However, some research suggests that an underactive thyroid may contribute to the progression of certain types of bipolar disorder, especially if someone suffers from it. predisposed to the condition. Thyroid function may also influence the severity of symptoms.

Changes in the hypothalamic-pituitary-thyroxine (HPT) axis. are common for bipolar disorder. The HPT axis regulates many body functionsincluding levels of hormones and neurotransmitters related to mood and thyroid function.

Research on this connection has not yet yielded definitive results, but 2021 study suggested that thyroid hormone levels in people with bipolar disorder may change over time. mood episodes. Study participants experience manic episodes (periods of elevated mood) appeared to have higher thyroid hormone levels than those experiencing depressive episodes.

But small study 2019 contradicts these conclusions. The study found no evidence of significant changes in thyroid hormone levels between mood episodes in bipolar disorder.

A 2023 studystudying first episodes of bipolar disorder in women found clinical signs of thyroid dysfunction in 27% of participants who experienced a manic or hypomanic episode and in 60% who experienced depressive episodes.

In particular, the researchers found that tests for the hormone triiodothyronine (T3) showed lower hormone levels in people experiencing a first episode of bipolar depression than in those experiencing a first episode of mania or hypomania. Lower T3 levels are also associated with more severe symptoms.

The researchers concluded that the results may show that thyroid dysfunction disrupts mood and influences the progression of bipolar disorder in people already predisposed to the condition.

Additional studies involving different populations and larger sample sizes are needed to further understand the mechanisms underlying this relationship.

Although the exact mechanism is unclear, experts believe that lithium suppresses the release of thyroid hormones T3 and T4 (thyroxine).

A another study 2023 found that 32% of participants receiving long-term lithium treatment for bipolar disorder developed thyroid disease during treatment. Of these, 79% were diagnosed with hypothyroidism.

Ultimately, the relationship between hypothyroidism and bipolar disorder is complex and misunderstood. It includes factors such as the role of thyroid hormones in mood, type of bipolar disordermain causes of hypothyroidism and type of treatment.