Learning about histones has made me really excited about being a psychotherapist. What are histones, you ask? No, they're not long-lost Freudian artifacts or a new kind of music therapy. They are proteins that exist in all of our cells, around which DNA is wrapped. You probably know that DNA -- deoxyribonucleic acid -- is the chemical that makes up our genetic code. It exists in the nucleus, or command center, of all of our cells. If stretched out, the DNA of each cell would be about six feet long, which is not a practical form for fitting into a microscopic package. So the DNA folds around the histones, like thread wraps around spools, to create the super compact shapes that are our chromosomes. With me so far? OK -- let's keep going.
Sections of the DNA that determine the make-up of particular proteins are called genes. These proteins are the building blocks of everything in our body -- bones, brain, blood cells, etc. When the DNA folds, some genes are open or available to make proteins, and other are not. So the way that DNA wraps around histones effectively dictates which genes make proteins -- basically, which genes are turned "on." Now, it turns out that, at least in animals, small chemical changes can happen to the histones even after birth that change the way that DNA is wrapped and, consequently, which genes are turned on or off. These are called epigenetic changes. Literally, "epi" means "above, or in addition to," so these are changes that are above or in addition to changes in the genes themselves. Another way to say this is that they do not involve actual alteration of the DNA molecules -- just the way the molecules are folded.
It's already pretty interesting that scientists have discovered a way that the genetic code can be modified after birth. But it gets even more interesting because neuroscientists have found that parenting can cause profound epigenetic changes. For example, Michael Meaney of McGill University and his colleagues have found that when rat pups have attentive mothers, their histones are chemically modified differently than when they have neglectful mothers. So being well cared for turns on some genes that being neglected doesn't. These changes can affect the rats' behavior as pups as well as their later behavior as mothers. Two more things: 1) these changes persist when the pups grow into adult rats; and 2) if you put the neglected rats with attentive foster mothers, the histone changes reverse.
"OK," you say, "that's great. But what does it have to do with being a psychotherapist?" Right -- back to that. As a therapist, I've always believed that early experiences affect us for life. My patients come to me as adults seeking help for a variety of problems -- problems with relationships, their careers, their children -- that have become maladaptive patterns. Together we explore their early childhoods to understand how those maladaptive patterns got established. The man who can't commit to a relationship may have had inconsistent parenting that has made him wary of depending on other people, while the woman who keeps sabotaging her career may have had an overly critical parent. Understanding these connections and the way they dictate how we think about ourselves, relate to others, and adapt to stress, can help people to free themselves from the tyranny of early patterns to live more satisfying lives. I know that this happens because I see it in my office every day. But until now I haven't had any idea about how it happens.
Although the studies that Meaney and his colleagues conducted involved rats, we have every reason to suspect that the epigenetic mechanisms they discovered also happen in people. That means that what happens to us as children becomes part of our biology, affecting the way our genes are expressed and how our bodies are built. It means that our psychology is not apart from our biology -- it is our biology. This humbling thought helps me to understand why it is so difficult for people to change the patterns that they have spent a lifetime developing. And, when I explain it to my patients, it helps them understand that, too.
But even more than that, it allows me to imagine that some day this could help illuminate how psychotherapy works. Since neglected rat pups fostered by attentive mothers change their histones and their gene expression, might this happen to people? Of course, the reversal of epigenetic changes happened in the rats' infancy, but who's to say that this might not happen later in development as well -- for example, during therapy? That would make psychotherapy a way of reactivating development in the context of the therapeutic relationship, leading to lasting changes in gene expression, protein production, and patterns of thought and behavior. Thinking about psychotherapy in this way is a little different from the older idea that insight leads to change, but it's an idea that makes more and more sense to me as I treat patients. My experience, as well as newer theories about psychotherapy, all tell me that it's not what we say, but rather the power of the therapeutic relationship that often makes the biggest difference. Maybe someday we'll discover that it leads to epigenetic changes later in life. It will never replace good parenting, but it might just be the next best thing.