PURPOSE: Despite clinical evidences that hypothyroidism is often associated with cognitive dysfunction, affective disorders and psychosis, the effects of thyroid hormone deficiency on the adult brain have been largely unexplored. We investigated the hypothesis that hypothyroidism might affect cortical excitability and modulates inhibitory and excitatory cortical circuits by using Transcranial Magnetic Stimulation. MATERIALS AND METHODS: Cortical excitability was probed in 10 patients with overt hypothyroidism and 10 age-matched healthy controls. We tested motor thresholds and corticospinal excitability, cortical silent period and peripheral silent period, short interval intracortical inhibition, intracortical facilitation. Patients were evaluated at the time of diagnosis, as well as after 3 and 6 months replacement therapy with l-thyroxin. RESULTS: At baseline, patients showed decreased cortical excitability, with increased resting and active motor threshold and decreased steepness of the motor evoked potential recruitment curves. These changes were paralleled by longer cortical silent period and decreased short interval intracortical inhibition. After 3 months replacement therapy, all the parameters but short interval intracortical inhibition were restored to normal values. Short interval intracortical inhibition returned to normal values only after 6 months of replacement therapy. CONCLUSIONS: Thyroid hormones are needed to modulate cortical excitability and cortical inhibitory circuits in adults.
PURPOSE: Despite clinical evidences that hypothyroidism is often associated with cognitive dysfunction, affective disorders and psychosis, the effects of thyroid hormone deficiency on the adult brain have been largely unexplored. We investigated the hypothesis that hypothyroidism might affect cortical excitability and modulates inhibitory and excitatory cortical circuits by using Transcranial Magnetic Stimulation. MATERIALS AND METHODS: Cortical excitability was probed in 10 patients with overt hypothyroidism and 10 age-matched healthy controls. We tested motor thresholds and corticospinal excitability, cortical silent period and peripheral silent period, short interval intracortical inhibition, intracortical facilitation. Patients were evaluated at the time of diagnosis, as well as after 3 and 6 months replacement therapy with l-thyroxin. RESULTS: At baseline, patients showed decreased cortical excitability, with increased resting and active motor threshold and decreased steepness of the motor evoked potential recruitment curves. These changes were paralleled by longer cortical silent period and decreased short interval intracortical inhibition. After 3 months replacement therapy, all the parameters but short interval intracortical inhibition were restored to normal values. Short interval intracortical inhibition returned to normal values only after 6 months of replacement therapy. CONCLUSIONS: Thyroid hormones are needed to modulate cortical excitability and cortical inhibitory circuits in adults.
Authors: Bo Liu; Zhensong Wang; Liangjie Lin; Huan Yang; Fei Gao; Tao Gong; Richard A E Edden; Guangbin Wang Journal: Neuroimage Clin Date: 2020-10-31 Impact factor: 4.881
Authors: Giuseppe Lanza; Francesco Fisicaro; Raffaele Dubbioso; Federico Ranieri; Andrei V Chistyakov; Mariagiovanna Cantone; Manuela Pennisi; Alfio Antonio Grasso; Rita Bella; Vincenzo Di Lazzaro Journal: Front Aging Neurosci Date: 2022-09-26 Impact factor: 5.702