Hypothyroidism — known as low thyroid — may cause depression. Hypothyroidism is a “condition in which the body does not get enough thyroid hormone for optimal brain and body functioning.

Hypothyroidism may also be associated with an increased risk of heart disease, primarily because high levels of low-density lipoprotein (LDL) cholesterol — the "bad" cholesterol — can occur in people with an underactive thyroid. Even subclinical hypothyroidism, a more benign condition than true hypothyroidism, can cause an increase in total cholesterol levels and weaken the pumping ability of your heart. Hypothyroidism can also lead to an enlarged heart and heart failure.

Research has found a link between hypothyroidism and depression. Mental health issues. Depression may occur early in hypothyroidism and may become more severe over time. Hypothyroidism can also cause slowed mental functioning.