Hormones and Your Brain

When people talk about hormones and the brain, it’s usually about teenagers — everything from teen angst to the rollercoasters of high school relationships gets attributed to the hormonal changes of puberty. In reality though, hormones play a role in brain chemistry throughout our lives. With the aging of the U.S. population, there’s been an expanded focus in medical research on cognitive decline and neurological illnesses — and there’s increasing evidence that hormones may be key to understanding these problems. Keep reading to learn more about how hormone levels can impact your cognition, why hormones may help us understand diseases like dementia, and what you can do to stay healthy.

 
An Epidemic of Memory Loss
We’ve long known that memory and other indicators of cognitive acuity decline with age, but as the Baby Boomer generation heads into retirement new concerns have been raised about cognitive issues. People are living longer than they did in the past, but cognitive impairment can create a rapid decline in the quality of the retirement years. It’s especially frightening because rates of cognitive illness have increased even as better preventative care, nutrition, and exercise have been helping to lessen the impact of physical illnesses. For example, while the percentage of the population dying from heart disease decreased from 2000 to 2010, in that same decade deaths attributed to Alzheimer’s disease went up 68%.
 
Alzheimer’s disease is currently the sixth leading cause of death in the U.S. It is estimated that as many as 16 million Americans are living with cognitive impairment, and that one in three of those over 65 has a form of dementia at the time of death. From mild cognitive impairment (which is the difference between “normal” age-related cognitive decline and early dementia) to Alzheimer’s disease, mental deterioration places a major strain not only on the sufferers but also on those who must transition into the role of caregiver. We can’t stop aging — the greatest risk factor for Alzheimer’s — and there is currently no cure. However, understanding the impact of hormone levels on the brain may provide insight into ways to slow, stall, or even reverse cognitive impairment.
 
How Hormones Affect the Brain
The body has many hormones, but colloquially “hormones” tends to refer to the sex hormones. It’s widely accepted that these hormones — namely estrogen and testosterone — impact us physically, from libido to muscle mass to metabolism. However, these hormones also influence and even control different parts of the brain. This is one reason why the idea that there is a fundamental difference between the “male brain” and the “female brain” is so persistent.
 
Estrogens control the hippocampus, which is important to long-term memory, navigation, and orientation (insert your own joke about men’s inability to remember important dates or ask for directions here). Research has shown that when estrogen levels are lowered, the activity of the hippocampus drops. This creates problems with memory. Interestingly, it’s also been found that reducing testosterone in men — which allows estrogen to flourish — can improve memory.
 
Our sex hormones also seem to play a substantial role in how we experience pain. Research has found that women’s pain thresholds actually differ depending on where they are in their menstrual cycles. Lowered levels of testosterone increase the pain response, whereas higher levels bolster pain tolerance. Linked to this are androgens: These male sex hormones appear to stimulate areas of the brain that release opioids and endorphins, both of which mitigate the pain response.
 
We often talk about testosterone in terms of personality traits, for example, being more competitive and aggressive. However, like estrogen it also impacts specific areas of the brain. One area where male sex hormones are especially helpful is visual processing and coordination. You might not think that that has much to do with memory, but the ability to process visual images is a huge part of recall. It’s important to everything from recognizing the face of an acquaintance to being able to find your way home.
 
Estrogens, Progesterone, and Aging
We all know that decreased levels of female sex hormones are a major part of menopause. But did you know that memory problems — from simple forgetfulness or “brain fog” to measurable cognitive impairments — are among the most commonly reported symptoms of menopause? The changing levels of female sex hormones can have a major impact on memory due to the role both play in the brain.
 
When there’s not enough estrogen in the hippocampus, fewer synapses are formed. It’s believed that this is the part of the brain that’s not just responsible for long-term memory, but for turning short-term memories into long-term memories. With less estrogen, it’s more difficult for short-term memories — like where you left you parked — to be recalled later. Estrogen also works to help your memory by increasing levels of the neurotransmitter acetylcholine. Estrogen encourages the activity of the enzyme that stimulates the synthesis of acetylcholine; when this isn’t happening, it’s harder to form new memories. Lack of production of acetylcholine is one symptom of Alzheimer’s disease.
 
Progesterone, another sex hormone that drops after menopause, also helps with memory. Progesterone is extremely important to protecting your central nervous system. It guards your CNS against inflammation; helping to build the blood-brain barrier, reduce edema, and controlling cascading inflammation in the event of a major trauma like a heart attack. Along with estrogen, progesterone also helps protect the brain from toxins.
 
Testosterone and Aging
While the link between declining estrogen levels and memory loss in women has been established for a long time, it’s only in recent decades that we’ve begun to realize how much of an impact declining levels of testosterone may have on men’s minds. Researchers from the University of Washington found that weekly injections of testosterone — giving older men the testosterone levels of healthy young men — improved spatial and verbal memory. It has also been noted that men with Alzheimer’s disease or even mild cognitive impairment tend to have low testosterone levels.
 
That said, even increasing testosterone levels does not fully mitigate memory issues. Though some aspects of cognitive ability have been shown to improve, others — like language and attention — don’t appear to be impacted by bringing up levels of testosterone. Still, if key aspects of cognitive decline can be minimized, many will likely consider trying testosterone replacement therapy. Laboratory studies have also demonstrated that testosterone appears to protect the brain against two of the key changes that mark Alzheimer’s brains: Testosterone reduces the secretion of β-amyloid (a component of plaques) by changing how its precursor is processed, and it inhibits the growth of hyperphosphorylated tau, a protein found in advancing Alzheimer’s.
 
While women always have lower levels of testosterone than men, research has also shown that postmenopausal women may experience similar benefits from testosterone therapy. Women treated with testosterone showed significant improvement in verbal learning and memory compared with a control group who received a placebo. Though these are promising results, while there are testosterone replacement drugs on the market for men, none have received FDA approval for use by women.
 
Other Hormones that Influence Cognitive Function
Two other hormones worth mentioning are pregnenolone and cortisol, both of which can have a major impact on your memory as you age. Cortisol is familiarly known as the “stress hormone.” Pregnenolone has less name recognition, but it’s been called “the mother of all steroid hormones,” since 150 different steroid hormones (including DHEA and progesterone) are derived from it.
 
Pregnenolone
Pregnenolone is produced by the adrenal glands, liver, skin, retina, ovaries, and within the brain. It’s converted into different steroid hormones by the body on an as-needed basis, so pregnenolone has been linked to many different aspects of health including mood and immune function. Pregnenolone is especially key to cognitive function, and though it’s less well known outside of medical circles researchers have identified it as one of the most important factors in keeping your brain “young.”
 
Pregnenolone blocks GABA, a neurotransmitter that inhibits the firing of neurons in the brain. Stopping neurons might seem undesirable, but think of GABA as acting like a surge protector for your brain—when there’s too much brain activity at once, GABA stops your brain from “shorting out.” An excess of GABA, however, can impair cognition by shutting off neurons when it’s not really needed. When we age, our levels of pregnenolone drop and so less GABA gets blocked. Short-term memory problems — like forgetting why you walked into the other room or being unable to recall where you left your cell phone — can be related to these changes.
 
In addition, pregnenolone stimulates the formation of new brain cells. Studies with both animals and humans have shown that pregnenolone improves memory and concentration. For example, studies on people who do different kinds of repetitive jobs that nonetheless require precision and concentration (like optical workers and lathe operators) found that prenenolone also improved the workers’ ability to cope with job-related stress and to feel less tired while they worked. Other research with animals has implied that pregnenolone can potentially make up for memory deficits. It’s also notable that none of this research found negative side effects, and that the effects of the pregnenolone supplementation continued even after it was stopped (likely due to the hormone’s impact on brain cell growth).
 
Cortisol
We think of cortisol as the “fight or flight” hormone, helping your body by regulating blood pressure, glucose metabolism, immune function, and insulin levels. While this is helpful for quick, intense moments of stress, we now know that having a high level of stress over time — and thus high levels of cortisol — has many negative effects on the body. These can include increased blood pressure, problems with blood sugar, reduced thyroid function, and decreased bone density.
 
Elevated cortisol levels are also linked to cognitive impairment. Cortisol affects cells in your brain’s hippocampus and amygdala, which are vital to learning and long-term memory. Interestingly, increased levels of cortisol have been found to help new memories form (maybe that’s why last-minute cramming for a test can seem like a good idea!). At the same time though, increased levels of cortisol when you’re trying to retrieve those memories — like if you’re feeling stressed during the test because you aren’t convinced the cramming worked — can impair memory. Research from the University of Zurich published in the Journal of Cognitive Neuroscience found that people who had higher levels of cortisol had more difficulty with recall in a variety of experimental conditions. In this study, the positive effect of cortisol on encoding memories wasn’t found; the key difference maker was the individual’s cortisol level when he or she was trying to retrieve the memories.
 
How Can You Support Your Brain Health?
Here’s where you can breathe a sigh of relief: Though there are no cures for Alzheimer’s disease or dementia, there are a number of ways you can support your cognitive health. Some factors, like age and family history, are out of your control, but there are many others that you can manage. Research from Finland has shown that the kind of lifestyle changes that will improve your overall health — like getting regular exercise, eating a healthy diet, and keeping blood pressure and cholesterol levels in check — can also help to slow cognitive decline.
 
Limiting your sugar intake — a step that will also help your health in myriad other ways — can support your brain health. High sugar diets are correlated to an increased risk of developing Alzheimer’s disease. Even worse, processed sugars are often found in foods where you wouldn’t necessarily expect to find them, like packaged soups and crackers. It’s another reason that a whole food diet — focusing on veggies, fruit, lean protein, and healthy fats — can help you achieve better health.
 
Given the impact that elevated cortisol levels can have on your memory (not to mention what we already know about what it can do to your circulatory system and muscles!), taking steps to reduce your stress level may also help to support your brain health. Making sure that cortisol doesn’t get out of control will have cumulative positive effects on your mental, emotional, and physical health. Making sure to pencil some “me time” into your daily schedule to unwind and keep stress in check is an especially pleasant way to support your cognitive functioning.
 
Given how vital hormone levels are to brain function, maintaining optimal hormone levels can potentially help you maintain your memory and other cognitive functions. It’s important to get your hormone levels tested, which can be done easily using either blood or saliva. Establishing a baseline and then regularly retesting can help you understand your body’s needs. If you are facing the changes of menopause or andropause (male menopause), balancing hormone levels with bio-identical hormones can mitigate the impact of these physical changes, including memory loss. Want to learn more about hormone testing and achieving hormonal balance? Come to Rejuvé for a one-on-one consultation and personalized advice from Dr. Tang. Call us at 408-740-5320 to set up your appointment.