Thyroid hormones,psychophysiological reactivity,and anxiety

Thirty-eight adults were assigned to three groups: posttreatment hyperthyroid (n=13), low euthyroid (n=12), and high euthyroid (n=13). Physiological and subjective responses to three anxiety-induction procedures—public speaking, personally distressing imagery, and threat of shock—were compared across groups. Although there were differences across stressors for physiological and subjective measures, group differences were not detected. Results are discussed with regard to the risk for residual anxiety following treatment for hyperthyroidism and the possible influence of thyroid function on the etiology or maintenance of anxiety.     

A multicomponent investigation of the interaction of generalized anxiety and phobia

Forty female undergraduates forming four groups, high or low trait anxiety with or without a specific fear (rats), participated in a psychophysiological assessment of their response to the phobic object, a neutral object (rabbit), and to a general anxiety-induction procedure (threat of shock). Subjects also completed a number of tasks requiring sustained attention. Blood samples were drawn to determine thyroid hormone (T3 and T4) levels. Trait anxiety was found to interact with specific fear in response to the feared object. The high-trait anxious/high-fear group was most physiologically responsive to the rat. Trait- anxious subjects were more responsive to the threat of shock and showed performance deficits on reaction time, vigilance, and backward digit span tasks. These subjects also had significantly higher T3 and T4 levels. The findings are discussed with regard to the role of general anxiety in the etiology and/or maintenance of specific fears and the role of thyroid hormones in accentuating physiological response to feared stimuli.