In this final article in my series on the connection between hormones and mood, I will be examining how thyroid hormones impact brain health and psychology. I will also briefly highlight the role of testosterone and oxytocin on emotional well-being. Below is a summary of what has been covered in previous sections.

Part one of this series explored:

Part two reviewed:

  • Specific interactions between estrogen and progesterone and the brain neurotransmitters of serotonin, GABA, dopamine, and glutamate
  • the connections between estrogen and progesterone and psychiatric disorders including anxiety, depression, and OCD (obsessive compulsive disorder)
  • the caveats of using hormonal replacement to treat mood disorders
  • naturopathic solutions to achieve optimal estrogen and progesterone levels and emotional harmony

For an overview on how cortisol, the major stress hormone, impacts the brain and body, please refer to my preceding essential oils’ series. (Part 1, Part 2)

Now, for the series’ conclusion.

Thyroid Hormones Crucial Impact on the Brain and Psychology

Thyroid hormones (THs) play a crucial role in brain formation and functioning of the central nervous system. Critical times during the prenatal period require adequate THs for normal cognitive development, growth, neural differentiation, and metabolism. (R, R, R, R)

This brain-thyroid interaction also continues throughout the lifespan. There are specific transporters and enzymes for THs regulation in the brain that impact neurological and mental functioning and interact with other neurological signaling patterns. Furthermore, imbalances in THs have been associated with brain injuries and various neurological and behavioral disorders, demonstrating that THs serve a neuroprotective function. (R)

Thyroid hormonal function has also been implicated in adult psychological and cognitive states. (R, R) Animal studies have indicated that THs may influence serotonin and noradrenaline levels, suggesting a possible psychiatric mechanism. (R). Human studies, however, have reported mixed results on the association between depression and subclinical hypothyroid and thyroid autoimmunity patients. (R, R, R, R, R, R)

These conflicting studies may be related to the many factors implicated in THs role on the brain and the various aspects involved in hormonal regulation, production, metabolism, elimination and utilization. Interesting, one meta-analysis found that the link between mood and thyroid levels may be related to age. The researchers reported that younger patients, who experience the most fluctuations in hormones, exhibited more of an association. (R)

Reports on using thyroid hormone replacement for treating depression have also been mixed. This too may be related to the individual, prescribing differences, and subpopulations. (R, R) For example, there exists genetic variations in individuals for enzymes and transporters for THs, which would impact efficacy of thyroid hormone replacement. Personalized approaches may yield better results.


Naturopathic Approaches to the Thyroid-Mood Connection

Due to the extensive and intricate interactions with the thyroid, the brain, and many bodily symptoms, doctors may miss anxiety, depression, and other psychologic symptoms in a man or woman with suboptimal thyroid functioning. Furthermore, the physical manifestations of low thyroid can be overlooked if it is diagnosed as a psychiatric condition. This means the root cause of digestive upset, fatigue, alterations in body weight, poor focus and memory, mood changes, and appetite shifts would never be effectively addressed. (R)

Due to the many ways that thyroid hormone physiology is impacted, addressing these regulatory aspects first may be more helpful than simply replacing thyroid hormone for mood. In my series on the many factors involved in “tweaking” hormones, I reviewed a naturopathic approach to balancing hormones.

This post reviews all these factors in relationship to THs and focuses on the “top offenders” of thyroid imbalance. These include stress, dietary and blood sugar imbalances, and microbiome and gut disorders. Within every section, I provided examples and/or links to which essential oils may benefit each circumstance. Click here if you would like to learn more and get the details.

Testosterone and Mental Health

The interaction between testosterone and specific neurotransmitters is not fully conclusive, but there is evidence from animal studies that there may be an interaction between it and dopamine. (R, R, R) The role of testosterone in mood in men has gotten the most focus in research, and outcomes are most favorable for replacement when levels are low and properly prescribed.

For example, appropriate testosterone replacement (TR) has some evidence that it may decrease nervousness and enhance energy and friendliness in men with suboptimal levels. It is also now believed that the relationship to TR and aggression may have been overstated; however, TR that artificially elevates testosterone to higher than physiologic levels may increase the likelihood of hostility. (R, R, R, R, R, R)

Several studies have exhibited correlations to testosterone levels and psychological disorders in women with disorders involving high androgens, such as PCOS (polycystic ovarian syndrome). (R) Yet, the results for using TR in women to improve mood symptoms has been inconsistent. This again may be related to the many individual factors involved in hormonal utilization. TR is also likely to be most effective when levels are low and there are other symptoms of imbalanced androgen levels present, such as fatigue and low libido. (R, R, R, R, R)

A naturopathic and/of functional medicine doctor would take a thorough case history, and, as with any hormonal imbalance, address the root cause of testosterone imbalances.

 Oxytocin and Psychiatry

Oxytocin is a hormone that has been associated with social behavior, bonding, and relationships. Therefore, it is no surprise that is implicated in mood and behavioral disorders. (R, R, R, R) Studies  have been promising for its use with autism. Other psychiatric illnesses, such as schizophrenia and other mood disorders, however, have shown inconsistent results.(R)

In a review article on obsessive compulsive disorder (OCD), it was suggested that oxytocin may have neuromodulatory effects and impact serotonin levels. If this was the case, it may be most impactful in those who have low serotonin levels, such as OCD sufferers. Studies, however, have shown mixed results. (R, R) Other research has suggested that oxytocin may impact dopamine signaling, the neurotransmitter related to motivation, reward, and focus. (R) This later effect may be one reason it has been studied for behavioral issues.

These differing reports could be related to individual variations in genetics, epigenetics, and personality type. In an extensive review of the research on oxytocin and mental health, the authors state:

The implications of the growing evidence for the role of oxytocin in neuropsychiatric disorders are far-reaching. First, the evidence suggests a role of oxytocin in the pathophysiology of some psychiatric disorders, particularly those characterized by impairments in social functioning. However, the preliminary nature of the currently available data precludes a clear understanding of the exact nature of this role.

Summary on the Hormone-Mood Connection

Hormones have a complex interaction with neurotransmitters and impact behavior and emotions through various mechanisms. This may be why an imbalance in these imperative chemical signals are linked to a variety of mood disorders.

It is important to keep in mind that many factors need to be considered when balancing hormones and mood. As a naturopathic doctor, I look at the root cause of any imbalance, especially hormonal.

Beyond the legal and ethical reasons of only covering up one’s symptoms, my training in biochemical individuality, love for personalized medicine, and my obsession for addressing the root cause, makes me passionate to exquisitely match the individual with the right wellness protocol. This is based on an intimate knowledge of their health history, personality, lifestyle, and our therapeutic relationship, not just a lab value or chief complaint.

If you believe hormonal imbalances are impacting your wellness and emotional health, please make sure you talk to your health provider. Also, consider additional support from an integrative or naturopathic doctor who is well-versed in addressing the many aspects of hormonal balance.

Free Resource!

I recently premiered a two-part series on using essential oils to regain emotional and hormonal harmony. The goal is to help assist you with brain, mood, and hormonal balance, which are all interconnected. Learn more here.

Mental Health Resources

*If you are experiencing a mental health crisis and/or are suicidal, please seek professional mental health support:

  • The National Suicide Prevention Lifeline (U.S.) — Call 1-800-273-TALK (8255)
  • Crisis Text Line — Text HOME to 741741 to connect with a crisis counselor
  • Lifeline Crisis Chat — Chat online with a specialist who can provide emotional support, crisis intervention and suicide prevention services at


Other Helpful Resources

Below are some of the highlights of the many free resources on this website:


Additional Supportive Techniques & Tools


If you need more individualized wellness support, please click the links for more information on essential oils or naturopathic consults.




Access My Video Series on Regaining Emotional and Hormonal Harmony with Naturopathic Medicine & Essential Oils

Disclaimer: This material is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness. You should check with your doctor regarding implementing any new strategies into your wellness regime. These statements have not been evaluated by the FDA. (Affiliation link.)

According to experts and the World Health Organization (WHO), there is no approved standard of care treatment, cure, or preventative for COVID-19. Supportive measures and containment are in full force as a result. Please see the CDC website and your state’s website for more information and updates. They also state when to contact your physician related to symptoms and travel history, exposures. Please read my more detailed article on this subject here.

This information is applicable ONLY for therapeutic quality essential oils. This information DOES NOT apply to essential oils that have not been tested for purity and standardized constituents. There is no quality control in the United States, and oils labeled as “100% pure” need only to contain 5% of the actual oil. The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin. The studies are not based solely on a specific brand of an essential oil, unless stated. Please read the full study for more information.

Thanks Pixabay and Canva.

Learn More About Naturopathic and Functional Medicine Services

Digestive, Hormonal, and/or Mood Imbalances Got Ya’ Down?