Thyroid function in causal relation to MRI markers of cerebral small vessel disease: a Mendelian randomization analysis.

This study indicated that genetically predicted increased TSH was associated with increased MD, as well as increased FT4 with increased FA, implying the causal effect of thyroid dysfunction on white matter microstructural damages. There was no evidence for causal relationships of hypo or hyperthyroidism with CSVD. Further investigations should verify these findings and clarify the underlying pathophysiological mechanisms.