Hormonal Update Volume 2 Number 10

Am I Losing My Mind or My Estrogen?

Hormones and the Brain, Part 1

Almost all of us have forgotten - where we put our keys, a casual acquaintance’s name, or a word right in the middle of a sentence. Often called “senior moments” these little memory failures are quite common. They come with that tip of the tongue sensation while the brain searches for the missing information. Then there is the “Aha moment” when the name or word pops into our mind. This is normal age-related loss of memory and it has to do with the speed with which our brain is able to retrieve information. 

These momentary memory lapses hardly faze us when we are in our twenties or thirties. When it happens in our forties, it gives us pause. We realize the clock is ticking and we are getting older. By the time we are in our fifties or beyond, a memory lapse mid-sentence can hurl us into a whirlwind of worry about whether or not Alzheimer’s is setting in. For most of us this is not the case. Many factors contribute to memory loss as we get older - stress, depression, fatigue, unrecognized changes in hearing or vision, medications, a poor diet, excessive drinking, even a hectic life can all play a role. 

The old school of brain science believed that we were born with a certain number of brain cells and that over our lifetime we lost approximately 10,000 of them per day. In the last decade, however, that theory has been upended and replaced by a much more complicated view of the physiology of the brain. We now know that new brain cells are formed in the adult brain, perhaps as often as every day. Exciting new animal studies have shown that in response to the stimulation of exercise, socialization and new learning opportunities nerve cells are also continually being produced. 

Age-related memory loss does not appear to involve the loss of neurons. Neurons are the impulse conducting brain cells. They are composed of dendrites. Dendrites are thread-like appendages that transmit impulses or messages across synapses (junction between cells) with the assistance of neurotransmitters. Neurotransmitters are chemical substances like acetylcholine, serotonin, or dopamine. 

So, if we aren’t losing brain cells, and nerve cells do continue to grow, what causes age related memory loss and the more serious, dementia or Alzheimer’s? Age related memory loss appears now to be more an issue of chemistry than anatomy. The brain is still intact, it just may lack some of the fuel it needs to function properly. 

Brain research is one of the most exciting frontiers in the scientific community. New technologies allow us to view the brain in ways not previously available, yielding exciting new information on how the brain works. Researchers are investigating the interplay between hormone balance and brain function. In our next two bulletins we take a look at the role hormones have in brain function and memory.

Hormonal Transitions and Fluctuations

Some researchers believe that while hormone levels can dramatically affect brain function, hormonal fluctuation and change may have an even greater influence on memory and mood. Most PMS research focused on the emotional aspects of the hormonal disorder, but there are cognitive consequences as well. Women with PMS have more difficulty with memory access, or retrieval, than women who have not experienced PMS. More studies are needed to determine why some women are more susceptible to these changes than others. 

Women in the third trimester of pregnancy have a harder time remembering what they have just read than non-pregnant women. Interestingly, estrogen levels are more than 1000 times higher during the third trimester than in normally ovulating women. Pregnant women also often report more anxiety and depression during the third trimester. 

Experimental studies have shown that rising levels of estrogen immediately following birth can impact directly on the mother’s brain and increase maternal behavior. Interestingly, new studies have shown that estrogen may help new dads feel more maternal as well.

Preliminary studies at the Mayo Clinic have demonstrated that men may experience hormonal changes that make them more apt to care for new babies. Salivary cortisol, testosterone and estradiol levels were measured in men who attended prenatal classes beginning in the first trimester of their wives’ pregnancies and ending three months after the baby’s arrival. Statistical analysis of the saliva hormone level results revealed that the new dads had significantly lower levels of cortisol and testosterone and higher levels of estradiol. While more studies are needed to determine whether this increase in estradiol is impacting new fathers in the same way it impacts new mothers, speculation is high that it does. 

Estrogen and the Brain

A substantial volume of scientific research clearly demonstrates that estrogen is essential to optimal brain function. There are estrogen receptors on brain cells throughout the brain. Estrogen seems to protect neurons from the kinds of stress, injury, and damage implicated in the development of Alzheimer’s disease. It also promotes the growth and viability of brain cells and the dendrites. In addition, the brain depends on blood flow to function. Estrogen increases blood flow through the brain, and acts as an anti-inflammatory agent protecting blood vessel walls from plaque formation. 

As estrogen levels fall during the years surrounding menopause, brain volume begins to decline, particularly in the hippocampus - the area associated with memory and cognition. This loss does not begin in men until nearly a decade later, around the age of 60. During this perimenopausal phase women often complain of decreased mental clarity and short-term, or verbal memory problems. As early as two months after surgical removal of the ovaries (oophorectomy) and the ensuing decrease in estrogen levels, women frequently experience a decline in cognition. Studies show that women who use estrogen replacement score higher on verbal memory and abstract reasoning tests.

Hot Flashes and the Mind

Nearly 85% of perimenopausal women experience hot flashes. The prevailing wisdom that hot flashes are a symptom of low estrogen levels may be an overly simplified explanation. Interestingly, science has now found a correlation between hot flashes and decreased cerebral blood flow. And, in women who no longer have their ovaries, a correlation between decreased blood flow and impaired cognition has been shown. In fact, it now seems that hot flashes themselves may lead to degenerative changes in the brain. The patterns of diminished blood flow occurring during hot flashes are similar to those that occur in people with Alzheimer’s disease. Estrogen replacement restores normal blood flow and decreases hot flashes.

Blue Mood

In addition to the malaise that can come with hot flashes, night sweats, and insomnia, nearly 80% of perimenopausal women complain of symptoms of mild depression. Sometimes these feelings stem from the awareness that we are growing older, or from empty nest syndrome - now that the kids are gone, what am I going to do - or from the added responsibility of having to care for elderly parents.

The areas of the brain responsible for emotions are fertile ground for estrogen receptors. Estrogen significantly influences the production and concentration of key mood neurotransmitters like serotonin, and increases opioid and endorphin production by the hypothalamus. Women on estrogen replacement report a much greater sense of well being, and significantly improved mood. And, estrogen seems to have its most powerful effect on depression among women with postnatal or perimenopausal depression.