Psychosomatic concept of hyperthyroidism - Graves type: Behavioral and biochemical characteristics

Abstract

In this study we test the hypothesis that specific behavioral and biochemical vulnerabilities characterize individuals with hyperthyroidism-Graves type, one of the classically cited "psychosomatic disorders". The sample included 24 subjects with Graves disease and 34 controls. All participants were evaluated for personality and temperament characteristics and for platelet MAO activity. A smaller group of panic disorder patients was tested with the same set of measures to ensure a validity of the study, especially regarding results on personality tests. Individuals with hyperthyroidism had lower platelet MAO activity and higher scores on histrionic (Hy), depressive (D) and hypochondriac (H) subscale on the MMPI-201 than normal controls. Their TPQ temperament scores were characterized by high Harm Avoidance, whereas other temperament traits were average. Platelet MAO activity was inversely correlated with the MMPI-201 psychopatic deviance scale (Pd) and positively correlated with the TPQ Reward Dependence scale. Our results provide support for the psychosomatic concept of Graves' disease. Personality features, temperament traits, and platelet MAO activity of hyperthyroid individuals are different from those in normal controls and correspond to those observed in anxiety disorders. We propose that the observed behavioral and biochemical similaritites between hyperthyroid and anxiety disorder patients represent an equicausality phenomenon, where the same underlying heritable factors, such as variable central monoaminergic activity coupled with temperament-related susceptibility to stress, facilitate phenotypic manifestation of a number of psychosomatic and psychialric disorders--including Graves disease. The observed correlations between personality traits and MAO activity provide support for the hypothesized functional relationship between the underlying central monoaminergic activity and temperament traits associated with anxiety, depression, and impulsivity.