Can iodine deficiency cause chronic clinical depression?

Thyroid, Depression. The thyroid gland requires an adequate supply of iodine to function normally. If there is a lack of iodine (which is unusual in the us), or if there is a problem with the functioning of the thyroid, then it is not uncommon for people to have some of the symptoms of depression. Technically, this is not diagnosed as depression; instead, it is called "depression secondary to thyroid insufficiency".