A young adult had sudden psychosis — like hearing voices and mood changes — and it turned out to be the first sign of an overactive thyroid caused by an immune system problem. This shows that sometimes, mental health symptoms can actually be caused by a physical illness.

Sometimes, a serious thyroid problem called Graves’ disease in young adults can come with mental health symptoms like hearing voices, mood swings, trouble sleeping, and memory issues — and both the thyroid and mental symptoms might get better with the right medicines.

If someone has an underactive thyroid and signs of an overactive immune system — especially bulging eyes — doctors should still think about Graves’ disease, even if the thyroid isn’t overactive.

In Graves' disease, the body's immune system accidentally attacks the thyroid by making antibodies that turn it on too much, causing it to overproduce hormones and leading to a condition called hyperthyroidism.

Sometimes, the first sign of an overactive thyroid caused by Graves’ disease is psychosis — like confusion or delusions — and blood tests can confirm it’s due to this specific condition.

Sometimes people can have Graves’ disease and show symptoms like bulging eyes or skin issues even if their thyroid isn’t overactive—this can happen if their thyroid doesn’t work well enough to produce excess hormones, and it means doctors might miss the disease if they only check thyroid levels.