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Thyroxine replacement increases central 5-hydroxytryptamine activity and reduces depressive symptoms in
A J Cleare1, A McGregor, S M Chambers
1Department of Psychological Medicine, Institute of Psychiatry, London, UK.
Neuroendocrinology
|July 1, 1996
Summary
Thyroid hormone replacement therapy can restore normal serotonin (5-HT) function in hypothyroid patients. This improvement in serotonin pathways correlates with reduced depressive symptoms.
Area of Science:
- Neuroendocrinology
- Psychiatry
- Metabolic disorders
Background:
- Hypothyroidism is linked to decreased central serotonin (5-HT) activity and higher depression rates.
- The impact of hypothyroidism on central 5-HT neurotransmission and its reversibility requires further investigation.
Purpose of the Study:
- To determine if thyroxine replacement therapy restores normal central 5-HT function in hypothyroid patients.
- To assess the relationship between thyroid hormone levels, serotonin function, and depressive symptoms.
Main Methods:
- Seven hypothyroid patients were evaluated before and after thyroxine replacement.
- Central 5-HT responsiveness was measured using cortisol and prolactin responses to d-fenfluramine.
- Thyroid-stimulating hormone (TSH) levels and depressive symptoms were also assessed.
Main Results:
- Thyroxine therapy significantly increased 5-HT-mediated cortisol responses.
- Depressive symptomatology improved following treatment.
- TSH levels showed a positive correlation with depressive symptoms and an inverse correlation with cortisol responses.
Conclusions:
- Central 5-HT neurotransmission is impaired in hypothyroidism.
- Thyroxine replacement therapy can reverse the reduction in 5-HT responsiveness.
- Restoration of 5-HT function may contribute to the improvement of depressive symptoms in hypothyroidism.