Subclinical Hypothyroidism: behavioral and psychophysiological characteristics.A pilot study

Background: Clinical hypothyroidism affects various aspects of cognitive and affective brain function. The most severe hypothyroidism may also mimic a picture of melancholic depression and dementia. Subclinical hypothyroidism (SHT) is characterized by elevated TSH levels despite normal thyroid hormone concentrations. The aim of this research is to verify the presence of a typical psychophysiological pattern in SHT patients. Methods: Since 1998 fifty patients who underwent surgeries at the Department of Endocrinology, University of Pisa, diagnosed with SHT, were subsequently recruited. Subjects underwent an inspection of the reported symptoms using the Crown & Crisp Experiential Index, and a psychophysiological assessment with a simultaneous recording of the parameters Skin Conductance Level/ Response (SCL/SCR), Surface Frontal Electromyogram (EMG), Peripheral Temperature (PT), Heart Rate (HR). As a control group, fifty subjects without endocrine disorders were subsequently recruited. Results: Data shows little difference in levels in hormonal assays except for TSH. There is also a significant elevation of some of the CCEI subscales: Anxiety, Depression, and Somatic Complaints. At the autonomic level, there is a general pattern of excessive arousal with significant differences in SCL/SCR, HR, and PT. Conclusions: A first data interpretation is that in sub-clinical hypothyroidism, the body tries to support and integrate the general lack of energy with an acceleration of the autonomic activity. This condition of initial arousal could be a useful indicator in order to monitor the treatment course and its effectiveness on the pathological evolution.