Endocrine Abstracts

Background: Mental fatigue, depression and anxiety are common in Graves’ disease (GD). Our aims were to assess the relationship between these variables among GD patients both in the hyperthyroid phase and after treatment. The pathogenic mechanisms involved in these symptoms are unknown and so is if previous psychiatric disease influences these symptoms.

Methods: This was a longitudinal case control study in Göteborg, Sweden, on 65 women with newly diagnosed GD and 65 matched controls. Consecutive patients were asked for participation and those included were examined in hyperthyroidism and after 15 months of treatment. Examinations included blood sampling, clinical evaluation, and psychiatric testing with the Comprehensive Psychopathological Rating Scale for Affective Syndromes (CPRS) and the Structured Clinical Interview for DSM-IV-Axis I Disorders (SCID-I). Mental fatigue was assessed with the Mental Fatigue Scale (MFS). The study also included a registry search for previous psychiatric diagnoses and previous prescriptions of psychoactive drugs in patients whom we asked for participation and in all Swedish women given a diagnosis of thyrotoxicosis during 2013–2018 compared to controls.

Results: There were no signs of an increased psychiatric comorbidity in the GD patients prior to the diagnosis when compared to matched thyroid healthy controls according to the SCID interview. In the registry search there was no difference in the prevalence of a psychiatric diagnosis or a prescription of psychoactive drugs between GD patients compared to matched controls. During the hyperthyroid phase, mental fatigue, depression and anxiety were significantly increased for GD patients compared to controls (all P < 0.001). At 15 months, significant improvements for GD patients were found for the items mental fatigue, depression and anxiety (all P < 0.001). The controls remained on a lower level. GD patients (38%) reported residual mental fatigue, 23.5% without depression and 15% combined with depression.

Conclusion: Graves’ hyperthyroidism greatly affects the patients´ mood regardless of whether the patient previously had a psychiatric diagnosis or not. Having had a previous psychiatric condition aggravated the psychiatric symptoms but was not the cause of them. Mental fatigue (MF) and emotional distress are common in the hyperthyroid phase. These improve with treatment but are still more common in GD patients after 15 months of therapy than in controls. The residual MF was detected in this study as an isolated phenomenon distinct from depression. This indicates the importance of assessing MF in GD patients and underlines the need for rehabilitation and healthcare support as MF will have consequences for work ability.