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Hormones and the Brain

Updated: Jun 1, 2023

Xiao Lung. Acrylic on canvas. artjamming studio Central, 2014.

I’ve found that the topic of hormones is one of the more confusing concepts in medicine. And that has a lot to do with the terminology that we use. It also doesn’t help that everything in medicine seems to have at least four names.

Hormones are basically signaling chemicals that help to coordinate functions across different parts of the body. Hormones mediate just about every aspect of bodily function, from helping us to digest and metabolize food, facilitating our response to stress. Most, but not all of our hormones are produced by our endocrine glands. So experts in hormones are called endocrinologists.

It doesn’t help that everything in medicine seems to have at least four names

Our brain cells, or neurons, are constantly in communication with each other through neurotransmitters or chemical signaling. Some neurotransmitters are classified as neuroendocrine chemicals because there is considerable overlap between brain and endocrine functions. For example melatonin is produced by the pineal gland in the brain, and regulates sleep and circadian rhythms.

It’s fair to say that scientists are continually discovering new areas of complexity in our brain and body functions. And much of what we are learning has to do with how the brain communicates with itself and with the rest of the body all day, every day, and actually even all night long as we sleep. So while we do know a lot about hormones, we are constantly learning more about the power of these tiny and miraculous molecules, and how they relate to brain health.

What do they do?

One major function of hormones is to help us to maintain a steady state, also known as homeostasis. For example, rising blood sugar (or glucose) levels will cause our body to respond by producing insulin, which brings the sugar level back down to a normal range. Think of it like a thermostat that is set to trigger the air-conditioning to cool things down when the temperature gets too hot (e.g. 24o celsius). Our “glucose-stat” has a set range that it considers to be normal, and when it gets too high, insulin release is triggered.

Photo by Dan LeFebvre on Unsplash

This concept of homeostasis is important to bear in mind, because it means that hormones typically come in pairs with opposing functions, so that there is a countermeasure if needed. And there are often neutralization mechanisms that ensure that active hormones are properly processed after they have done their job.

Hormones help us to maintain a steady state, also known as homeostasis

Our understanding of the endocrine system was classically based on anatomy. Some endocrine glands basically only produce hormones, like the thyroid or adrenal glands. Others are housed in structures that have other functions, for example the ovaries produce ova (or eggs), and also the female reproductive hormones estrogen and progesterone.

As we learn more about hormones, the brain and gut, we are actually realizing that they are sometimes produced by bacteria in the gut, a.k.a. the gut microbiome. Liver, muscle, and even fat cells can produce hormones and other signaling chemicals.

Sex and babies

Hormones in the common vernacular usually refer to sex hormones. We might say that a teenager is “being hormonal” when they are having mood swings. The male hormone testosterone is active in both men and women, and regulates everything from bone and muscle mass, to sex drive, to acne and hair distribution.

Female reproductive hormones play extremely important roles in women’s lives, from the time of puberty, through childbearing years and even through menopause. Our main hormones, estrogen and progesterone, cycle in response to signals from the pituitary gland in the brain causing ovulation and menstruation each month. Preparing the womb and body for pregnancy, just in case.

I have always found it fascinating to learn how our reproductive systems are hardwired to respond. After conception, a whole new cascade of hormones are triggered to maintain the pregnancy and to grow the placenta, until the placenta itself becomes an endocrine organ. After birth, hormones like prolactin and oxytocin kick in to stimulate and facilitate breastfeeding after birth, promoting maternal-infant bonding.

Photo by Simone van der Koelen on Unsplash

The miracle of modern medicine has allowed women to manipulate our hormones to stop having periods, prevent pregnancy, or to promote fertility, according to our convenience. But there are limits to what we can accomplish through science, and nothing that we have invented can compare with the elegant simplicity of Nature’s design.

We don’t fully understand the effect of gender on dementia risk. We do know that women are at a higher risk for getting dementia, even after taking into account the fact that women tend to live longer than men. It would be natural to infer that there may be some hormonal explanation for this gender gap in brain health. But so far we can only confirm that the perimenopause may be a time of vulnerability for women. What’s unclear is whether that can be attributable to sleep disruption, or what other factors may be at play.

Nothing that we have invented can compare with the elegant simplicity of Nature’s design

We have also known that women tend to be at lower risk for heart disease and strokes compared to men, up until menpause. So there is a protective benefit to having the natural cycling of hormones through menopause. But somehow that protective benefit does not translate when estrogen and progesterone are dosed in the form of pills or patches, in fact the risk for stroke or blood clots increases with age.

Eat and digest

Beyond reproduction, our bodies are designed to digest food that we consume, and to metabolize that food into energy. While many hormones participate in the digestive and metabolic process, insulin is the key player.

As noted above, insulin is released from the pancreas in the process of digestion. It signals the liver, fat and muscle cells to absorb excess glucose or sugar. When someone has Type 1 diabetes (T1DM), their body is unable to produce insulin, and so they have to take insulin shots. This is a relatively uncommon condition; Type 2 diabetes is way more common, and in fact we are facing a global epidemic of “diabesity” or diabetes and obesity.

Photo by Mykenzie Johnson on Unsplash

In Type 2 diabetes (T2DM), our bodies can make insulin, but it’s often not enough insulin to keep the blood sugar levels down, a condition that’s known as insulin resistance. In our thermostat example, the temperature gauge is malfunctioning and stuck at 28o C and so the room has to get really hot before the air-conditioning kicks in.

You may have heard that there is some scientific evidence to support the notion that there is such a strong link between diabetes and dementia, and that it may be considered Type 3 diabetes (T3DM) in the future. There is still considerable controversy over this theory at present.

What we have seen is that diabetic patients with better controlled blood sugars do appear to have improved brain health and cognitive function. We also know that well-controlled diabetes is strongly correlated with heart health and reduced risk for stroke. Diabetes is also believed to potentially play a role in causing inflammation in brain tissue, and high insulin levels may promote development of pathological changes like amyloid plaque and neurofibrillary tau tangles.

Taking action

We want science to be accurate and certain, but unfortunately it usually is not. New discoveries typically challenge existing dogma, and make things more confusing for a while, until enough time has passed to allow scientists to accumulate a lot more evidence, to either prove or disprove existing theories.

And while it’s important to keep up with new developments, we don’t have to allow our brains to stay in confusion or overwhelm. When it comes to lifestyle habits, science can serve as a guide for what to try, but we have to be our own guinea pigs. Whatever worked for someone else, or even 1,000 0r 100,000 other people, may or may not work for me. So it’s up to me to be willing to try new things, and to figure out how to track the outcomes that I care most about. And to take protective action to prevent worse outcomes.

For example, I am worried about my brain health even if I haven’t been diagnosed with diabetes yet, because I’ve seen how diabetes and dementia are so closely linked. I know for sure that I am at risk for diabetes since I have family history, am overweight, or have signs of insulin resistance. These might include blood tests showing prediabetes, or ultrasound scans confirming fatty liver or polycystic ovarian syndrome.

It’s up to me to be willing to try new things

Insulin resistance and Type 2 diabetes (T2DM) is actually completely reversible through lifestyle measures. It’s a matter of deciding where to start. Author of The Obesity Code, Dr Jason Fung, advocates a five pillar approach through The Fasting Method (TFM) program.

  • Time restricted eating (TRE) - two meals that are at least 5-7 hrs apart. Water and plain tea or coffee only between meals.

  • Both meals should be scheduled during daylight hours.

  • Whole, unprocessed foods with an emphasis on natural fats are favoured over processed foods.

  • Good sleep hygiene to promote high quality sleep.

  • Stress management.

Learn more about insulin resistance and what to do about it through the free podcast and resources at


1. Book - The Obesity Code Excellent summary of the science behind intermittent fasting as an evidence based approach to weight loss and blood sugar management.

2. Website

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