Iodine is a mineral used by the human body to produce thyroid hormones and so plays a major role in oxygen consumption and normal body function. It is important in brain development and function as well. Low levels can lead to impaired brain development in infants and impaired function in adults. Deficiency causes a slowing or depression of the brain, while higher levels can lead to nervousness, irritability and anxiety. It is this higher level, not deficiency, which is associated with hyperthyroidism and panic attacks.
Panic attacks are repeated bouts of intense fear in which the person may experience chest pain, heart palpitations, dizziness, fear of doom or losing control, choking feeling, nausea, vomiting, shortness of breath, trembling, chills, sweating, hot flashes and numbness or tingling of the hands, feet or face. The diagnostic criteria requires medical conditions be ruled out, including hyperthyroidism, before identifying the attacks as panic disorder.
One of the first documented associations between hyperthyroidism and panic attacks was noted in a case study published in 1983 in "Psychosomatics." Hyperthyroidism is a condition in which too much thyroid hormone is produced. One potential cause of hyperthyroidism is too much iodine. Symptoms include difficulty concentrating, nervousness, restlessness, fatigue, hand tremors, pounding rapid or irregular pulse, heart palpitations, nausea, heat intolerance and sleeping difficulties -- many of the same symptoms associated with panic attacks.
Iodine deficiency is often associated with hypothyroidism and goiters, the enlargement of the thyroid due to low thyroid hormone levels. Severe iodine deficiency in an infant can result in mental and growth retardation as well as death. The effect in the adult brain is not as severe, according to the Linus Pauling Institute, but can result in slower response times, impaired mental function, depression and fatigue.
The recommended daily allowance for iodine set by the Institute of Medicine is 150 mcg for most adults, but increases for pregnant women to 220 mcg per day and 290 mcg per day for breast-feeding mothers to ensure adequate amounts for the growing infant brain. Iodine content of foods varies depending on the iodine content of the soil in the area it is grown. It is most commonly found in iodized salt and seafood. Dairy products can be good sources as iodine is often added to animal feed. Linus Pauling Institute suggests keeping daily intake below the tolerable upper limit of 1,100 mcg per day to prevent hyperthyroidism caused by excess iodine, unless being treated with iodine by a doctor.
While thyroid disease can cause emotional symptoms and mood changes, it is unlikely these would be the only signs. Other symptoms include weight changes, sensitivity to temperature and changes in bowel function and menstrual cycles. If you experience anxiety, depression and/or panic attacks, be sure to discuss these conditions with your doctor to rule out medical issues that could be causing what appear to be mental issues.