Hormones, Metabolism, and Refractory Depression: What is the connection?
What role do hormones play in mental health and, more specifically, treatment-resistant depression? It’s a question that gets right to the heart of what many of my colleagues and I have been investigating for decades.
When we see a patient who’s been through the gauntlet of standard antidepressant therapies without success, the conventional approach often doubles down on more psychotropic medications or new “experimental treatments” that boast life-changing improvements that unfortunately don't often last. But what if we’re looking in the wrong place? Is "treatment-resistant depression" simply a case of underlying, undiagnosed hormonal deficiencies?
Based on a vast body of clinical evidence and my own clinical experience, I can tell you that in a significant number of cases, the answer is a resounding yes. The psychiatric symptoms are often the downstream consequence of a fundamental breakdown in the body's endocrine system and addressing this is of utmost importance, not just for mental health but for overall quality of life and wellbeing.
The Hormonal Symphony and Mental Health
Let's be clear: our brains do not operate in a vacuum. They are exquisitely sensitive to the hormonal symphony that governs our entire physiology. When that symphony is out of tune, the brain is often the first organ to send out an alarm, frequently in the form of depression, anxiety, or cognitive fog.
The relationship between hormones and depression isn't a new concept, but it is one that has unfortunately been tragically overlooked. There are numerous research papers that highlight the therapeutic use of various hormones to treat depression, yet this knowledge rarely translates into mainstream practice. Instead, we see a system that prefers to treat the symptom—the "chemical imbalance"—rather than the root cause.
Let’s break down the key hormonal players:
• Thyroid Hormone: This is arguably the most critical and misunderstood player in mood regulation. A staggering number of patients with persistent depression are suffering from what I call "thyroid hypofunction" at the cellular level, even with a "normal" TSH. Studies, including a pivotal one from The New England Journal of Medicine, have shown that adding T3 to T4 therapy significantly improves mood and neuropsychological function where T4 alone fails. In fact, research demonstrates that T3 is a potent enhancer of antidepressant action, and high-dose thyroid (HDT) is an effective and well-tolerated long-term augmentation strategy for “refractory depression”. The psychiatric literature itself supports this, yet endocrinology guidelines often proscribe its use, leaving patients to suffer needlessly. The connection is so profound that some researchers have argued that psychiatrists, not endocrinologists, should be the ones managing thyroid in these patients.
• Testosterone: In men, the link between low testosterone and depression is irrefutable. Hypogonadal men have a significantly higher prevalence of major depressive disorder, and testosterone replacement therapy often alleviates these symptoms where SSRIs have failed. One landmark study in the American Journal of Psychiatry found that testosterone gel produced significant antidepressant effects in men with refractory depression and low-normal testosterone levels. SSRIs can even lower testosterone levels, potentially worsening the very problem they are meant to treat. Women, too, benefit immensely. Testosterone therapy improves well-being, mood, and mitigates depression, yet this is almost universally ignored.
• Progesterone: Particularly in women, the anxiolytic (anxiety-reducing) and calming effects of oral micronized progesterone are profound. Its metabolites act on GABA receptors in the brain, much like benzodiazepines but without the same risks. We see this most acutely in perimenopause, PMS/PMDD, and postpartum depression, where mood disturbances are rampant and respond beautifully to progesterone supplementation. Progesterone is not just for the uterus; it helps with sleep, mood, and anxiety.
• DHEA: This adrenal hormone, often dismissed as a weak supplement, is a powerful neurosteroid. Multiple studies, including a randomized, placebo-controlled trial published in the Archives of General Psychiatry, found DHEA to be an effective monotherapy for midlife-onset major and minor depression. It improves mood, sexual function, and well-being, yet it remains almost entirely outside the standard psychiatric toolkit.
The Metabolic Connection: Insulin Resistance
We cannot discuss hormones and depression without addressing the elephant in the room: insulin resistance. Insulin resistance is a state of metabolic dysfunction that disrupts nearly every hormonal axis in the body. It drives inflammation, alters sex hormone binding globulin (SHBG) levels, and contributes to the hormonal chaos seen in conditions like PCOS, which has a strong link to depression.
Dr. Ben Bikman’s work eloquently illustrates that what we often label as distinct diseases—PCOS, Type 2 Diabetes, and even neurodegenerative disorders like Alzheimer's ("Type 3 Diabetes")—are all manifestations of insulin resistance in different organs. Dr. Christopher Palmer takes this a step further in his Brain Energy theory, proposing that all mental disorders are, at their core, metabolic disorders of the brain, driven by mitochondrial dysfunction. My clinical experience strongly supports this. When you treat the underlying insulin resistance with a comprehensive plan—which must include hormonal optimization—the depressive symptoms often resolve.
Conclusion: A Paradigm Shift Is Needed
So, while not every case of treatment-resistant depression can be reduced to a simple hormone deficiency, a vast number of them can. These patients are not "refractory" to treatment; rather, they have been refractory to the wrong treatment. Their depression is a symptom of a systemic, metabolic, and hormonal failure that has been overlooked.
The tragedy is that our current medical model, with its siloed specialties, often fails these patients. The psychiatrist manages the brain, the endocrinologist manages the glands, and the cardiologist manages the heart, without recognizing that they are all treating the same interconnected system. The solution lies in a more integrated, functional approach: one that assumes PCOS, thyroid hypofunction, and insulin resistance until proven otherwise, and uses bioidentical hormones to restore the body’s natural balance. When we do this, we don’t just treat depression; we restore health, vitality, and quality of life. It’s time we stop chasing symptoms and start treating the root cause.
- Luke Swift, DNP, APN-FPA, PMHNP-BC, ABHRT
Further reading:
Bunevicius, R, Kazanavicius, G., Zalinkevicius, R., et al. (1999). Effects of Thyroxine as Compared with Thyroxine plus Triiodothyronine in Patients with Hypothyroidism. New England Journal of Medicine, 340(424-429).
Pope, H. et al. (2003). Testosterone gel supplementation for men with refractory depression: A randomized, placebo-controlled trial. American Journal of Psychiatry, 160, 105-111.
Schmidt, P. et al. (2005). Dehydroepiandrosterone monotherapy in midlife-onset major and minor depression. Archives of General Psychiatry, 62(154-162).
Kelly, T. & Lieberman, D. (2009). Long term augmentation with T3 in refractory major depression. Journal of Affective Disorders, 115(230-233).
Miller, K. et al. (2009). Low-dose transdermal testosterone augmentation therapy improves depression severity in women. CNS Spectrums, 14(12), 688-694.
Kelly, T. (2014). A favorable risk-benefit analysis of high dose thyroid treatment of bipolar disorders with regard to osteoporosis. Journal of Affective Disorders, 166(353-358).
Kelly, T. (2015). An examination of myth: A favorable cardiovascular risk-benefit analysis of high-dose thyroid for affective disorders. Journal of Affective Disorders, 177(49-58). The World Journal of Men’s Health, 34(3), 194-199.
Jung, H. & Shin, H. (2016). Effect of testosterone replacement therapy on cognitive performance and depression in men with testosterone deficiency syndrome.
Kelly, T., Denmark, L., & Lieberman, D. (2016). Elevated levels of circulating thyroid hormone do not cause the medical sequelae of hyperthyroidism. Progress in Neuro-Psychopharmacology & Biological Psychiatry, 71(1-6).
Palmer, C. (2022). Brain Energy. BenBella Books, Inc.
Glynne, S. et al. (2024). Effect of transdermal testosterone therapy on mood and cognitive symptoms in peri- and postmenopausal women: A pilot study. Archives of Women’s Mental Health.
