As you probably know, Graves disease is a condition where the thyroid gland is stimulated to make to much thyroid hormone. Symptoms of Graves disease include insomnia, a tremor, feeling hot all the time, weight loss
, and depression. Dementia is typically not a symptom of having too much thyroid hormone. Dementia can be a sign of having too little thyroid hormone. Keep in mind that some of the symptoms of depression can seem like dementia. Short term memory loss is definitely one of them. Often after the Graves disease is properly treated, the symptoms of depression can subside. If your father has other signs of depression, he should be evaluated by a physician.
The best physician for your father to see is an endocrinologist
(who are the experts in Graves disease). I suggest that your father schedule an appointment with his endocrinologist with his new symptoms in mind. If his doctor
has evaluated him in the past, he will be able to make a call as to whether his short term memory has been compromised. In addition, his doctor will want to measure his thyroid hormone levels to make sure that his Graves disease is under control. This may include some combination of medications, a surgery or a thyroid gland ablation.