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.

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 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.

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.