Thyroid dysfunction associated with cognitive impairment in subcortical vascular disease

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  • Thyroid dysfunction was associated with cognitive impairment among individuals with subcortical ischemic vascular disease (SIVD), and serum total triiodothyronine (TT3) and serum thyroid-stimulating hormone (TSH) levels may prove to be biomarkers for cognitive dysfunction.

Key findings

  • There was a close correlation between thyroid status and cognitive dysfunction in SIVD.
  • TT3 and free triiodothyronine (FT3) levels fell and TSH levels increased in tandem with a decline in cognitive function.
  • TT3 levels were positively correlated with results of the Mini-Mental State Examination (MMSE), while TSH levels were negatively correlated with MMSE scores.

Study design

  • Cognitive performance was examined in 215 individuals, including 54 healthy controls, 52 participants with SIVD without dementia, 55 patients with SIVD who had mild cognitive impairment, and 54 patients with vascular dementia.
  • Serum TSH, TT3, FT3, total thyroxine, free thyroxine, thyroglobulin antibody, and antithyroid peroxidase antibody were quantified by radioimmunoassay or enzyme-linked immunosorbent assay.


  • Relatively small sample size.
  • Lack of repeated measuremnent of thyroid hormones.
  • Lack of follow-up data.

Why this matters

  • Thyroid status is a potential independent risk factor for reversible cognitive impairment.
  • Thyroid hormones play a central role in the maintenance of normal neural function.
  • Investigation into the association of thyroid dysfunction and vascular dementia subtype SIVD is sparse.