Your Momma Should Have Known
“Our brains develop according to a recipe encoded in our genes…The sequence of DNA in those genes is pretty much fixed. For experiences to produce long-term changes in how we behave, they must be somehow able to reach into our brains and alter how those genes work.”
– Carl Zimmer
Nothing against your mother. The point is that your mother and everyone’s mother should have been taught what you are about to learn, before you were born. The news is recent, but the information itself has been around since the beginning of our existence.
Caution: What you are about to learn may change what you think about life and how you understand the sometimes mysterious behaviour of others. You won’t be asked to convert to any way of thinking. It will simply help you to understand.
Human behaviour, or human nature if you will, may present the greatest mystery and challenge anyone has ever faced. For examples, men ask “What do women want?” while women wonder “What makes men tick?” Neither is a huge mystery, it’s just that we haven’t taught each other what a few of us already know.
The study you will read about could not have been conducted on humans. At least not on living ones. You will soon understand why. It was conducted on rats. And on the brains of people who had recently died, some from suicide. Just to make it more enticing, love has a great deal to do with it.
In humans, love is a mystery. The word has more definitions than just about any other in the Oxford English Dictionary. The problem is that we can’t get a handle on exactly what love is. Yet, in our own lives, we tend to quantify love. We don’t measure love as such. We measure loving touch.
In general, we touch those we love more than those we don’t love. When the romance of the early months of a new relationship filled with lots of loving touch fades and the touching reduces to little or nothing, we say that love was lost. People leave legal relationships seeking more and better love, but what they really seek is more loving touch. We tend to equate touch with love. We measure how much others love us by the amount they want to share loving touch with us.
Not so easy to test in a science lab. Especially when ethics intervenes when we want to prove that people change for the negative when they lack sufficient touch of others. Many labs have turned to rats as substitutes. The similarities between us and rats in these tests may make you uncomfortable, but they are real.
In one family of rats the mother was allowed to lick the fur of her babies, often and extensively. In another, the mother hardly licked her babies at all. As adults, the two groups of rats turn out very different. In the neglected group, the rats were easily startled by unexpected noises, they were reluctant to explore new places and their bodies produced lots of hormone when they experienced stress.
The licked and loved rats were not easily startled, showed great curiosity in exploring new places in their environment. And they “did not suffer surges of stress hormones,” according to Carl Zimmer.
They did not suffer surges of stress hormones. I do. Like many others, I lack the gene that should cause my adrenal gland to produce a hormone that neutralizes the effects of epinephrin (commonly known as adrenalin), the chemical produced by the adrenal gland to prepare us for action in times of sudden stress, known as the fight or flight response. In other words, when my body senses stress, I not only get the surge of adrenalin but it hangs around in my bloodstream for hours, even for days.
Why do some people suffer severely from stress–even to the point of thinking about or actually committing suicide–while others seem able to handle stress with relative ease? The rats in the experiment above and in hundreds of other labs may show us the answer. The rats–and at least some of us–may not be able to handle stress as well as others because our brains and bodies are not prepared for what amounts to prolonged chemical warfare on us. Self-induced chemical warfare.
Two families of molecules control when our genes turn on and off, which ones and for how long. One, the methyl group, essentially plugs the path for genes to express themselves by producing proteins. The other, coiling proteins, wraps our DNA into spools so tight the genes can’t become active. If either is too successful or lacking, something can happen with gene expression (or may be prevented from happening) that will affect our health and even our lives.
Our experiences can rewrite these two, collectively called the epigenetic code. Most of the writing or behaviour patterning is done before we are born. However, strong experiences after we are born–even extraordinarily strong experiences as adults–can rewrite the code.
Differences between the brain of the licked rats and the neglected ones were found in the hippocampus. The glucocorticoid receptor gene–the one that controls how long adrenalin stays in the bloodstream–for example, was capped off by methyl groups in the neglected rats and they had fewer receptors than the licked rats. Thus the neglected rats had fewer ways to stop adrenalin from doing its thing when it was no longer needed. They were permanently stressed out.
Neurobiologist Michael Meaney, of McGill University, and colleagues followed his rat studies by studying the brains of people who had recently died. Twelve had committed suicide and had suffered abuse as children, 12 had committed suicide but had not suffered abuse and the final 12 had died of natural causes. The suicide people who had suffered abuse had cortisol receptors capped by methyl groups and had fewer receptors, as they had found with the rats. Abuse in childhood had caused them to be permanently stressed as adults.
Another group studied suicide victims and people who died natural deaths and found methyl groups blocking the gene that produces the protein BDNF in the Wernicke area of the brains of the suicides. Environmental influences–everything after birth, including human interaction–can also affect adults.
Neuroscientist Eric Nestler, of Mount Sinai School of Medicine in New York City, examined the brains of mice that had been put through so much stress in conflicts with other mice that they were depressed. He found differences in an area of the brain called the nucleus accumbens, which is involved with the brain’s reward system and helps to set values on things based on the pleasure derived from them. He found the DNA in that part wound tightly with coiling proteins. Nestler’s group found the same kinds of epigenetic changes in the brains of depressed humans who had recently died.
Brain changes caused by coiling proteins and methyl groups should be able to be reversed, once we learn how. Nestler injected HDAC inhibitors into the nucleus accumbens parts of the brains of depressed mice to loosen the coils of DNA. Ten days later the mice were less hesitant about approaching other mice and other signs of depression were absent.
These studies suggest that previously intractable human troubles such as depression, suicide and a wide range of problems associated with constant stress (including those that impact the immune system) may be correctable. More study is needed and testing on humans will be tricky, maybe even risky at first.
Any change to the brain is risky. But it may be do-able. Medical science is still in the very early stages of learning about our most complex and sophisticated organ.
Soon taking a DNA sample of a newborn baby will be routine. The sample will be examined for variations from expected norms so the child can have a genetic adjustment made and avoid genetic problems and weaknesses that are an unfortunate part of life today.
Bill Allin is the author of Turning it Around: Causes and Cures for Today’s Epidemic Social Problems, a guidebook for teachers and parents who want to grow healthy children right from birth. This book shows us how.
Learn more at http://billallin.com
[Primary source: The Brain, by Carl Zimmer, Discover, June 2010]