A Graves' disease of identical twins with mental disorder.

We present here the clinical cases of identical twins with Graves' disease associated with various mental disorders. They showed restlessness, hyperexcitability, emotional instability, anxiety, depressive state, obsessive-compulsive manifestations, and delusions of persecution and reference. In the case of twin A, the psychiatric symptoms and Graves' disease were in parallel with their clinical course, and his psychiatric symptoms disappeared after a subtotal thyroidectomy. In the case of twin B, however, the psychiatric symptoms had almost disappeared during the period of hypothyroidism for two months after a subtotal thyroidectomy, but the symptoms recurred in spite of the data of euthyroidism in blood examinations after that period of time. It was suggested that the psychiatric symptoms of twin B were due to the euthyroid Graves' disease. The close resemblance of the psychiatric symptoms in both twin A and B might be based on the same genetic disposition due to their being identical twins.