Transient dementia during hyperthyroidism of painless thyroiditis. A case report

Yuichiro Ii, Takayuki Ohira, Yugo Narita, Shigeki Kuzuhara

Research output: Contribution to journalArticlepeer-review


We report transient dementia in a 71-year-old woman, that was caused by hyperthyroidism of painless thyroiditis. Her friends, who found her very forgetful and performing abnormal behavior, brought her to our hospital. She looked alert and cooperative. There was neither goiter nor pain of the thyroid. Neurological examination revealed impairment of recent memory with a low score of memory test (MMSE: 20/30) indicating mild dementia. EEG showed slow α waves (8Hz) with random η and δ waves in the frontotemporal regions bilaterally. MRI showed mild diffuse atrophy of the brain, and SPECT revealed diffuse decrease in the cerebral blood flow most predominantly in the frontotemporal regions bilaterally. Abnormal findings included low levels of thyroid stimulating hormone (TSH), high levels of free triiodothyronine and free thyroxine. Antithyrogloblin antibody was positive and TSH receptor antibody was negative, while CRP was normal. Radioactive Tc uptake of the thyroid gland was low. A diagnosis of painless thyroiditis was made. Thyroid function turned to euthyroid state spontaneously in four weeks without antithyroid therapy, and subsequently memory disturbance and abnormal behavior disappeared. SPECT after clinical recovery showed improvement in the cerebral blood flow of the frontotemporal lobes. To our knowledge, dementia-like symptoms secondary to hyperthyroidism of painless thyroiditis have not been reported previously, and should be kept in mind as one of the causes of treatable dementia.

Original languageEnglish
Pages (from-to)341-344
Number of pages4
JournalClinical Neurology
Issue number6
Publication statusPublished - 2003 Jun 1
Externally publishedYes


  • Dementia
  • Hyperthyroidism
  • Painless thyroiditis

ASJC Scopus subject areas

  • Clinical Neurology


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