Let’s Not Overstretch Neuroplasticity

Illustration by Nick Vokey; source image by _DJ_ (CC)

Sure, your brain is more dynamic than once thought. But harnessing those powers is tricky.

Ever since researchers discovered that, contrary to prior belief, the adult brain can grow new nerve cells, neuroplasticity has been a hot topic. Conventional wisdom had previously held that the adult brain couldn’t physically change much, let alone grow new cells. In essence, neuroscientists had posited that after young adulthood, the brain’s structure was set in virtual concrete, until disease, aging, or death destroyed it.

That position never really made much sense. While learning is certainly harder as you get older, it clearly happens all the time and, thankfully, adults often do completely change their ideas and behavior. And how could it be that interaction with the environment could change your brain structurally while you are young, but never again after you reach the legal drinking age? But this is basically how the science was conveyed to the public.

Now the pendulum has swung the other way. In the last few decades there has been an explosion of books and articles to popularize the idea that the adult brain can indeed change—not just functionally, but structurally. Between 1992 and 2008, according to Google Ngram, use of the term “neuroplasticity” in books rose by a factor of eight. Many of those authors argue that the possibilities of plasticity are nearly infinite—that it can restore sight, hearing, and movement to people with disabilities or reverse brain injury, mental illness, and disease.

In The Brain’s Way of Healing, for example, psychiatrist Norman Doidge includes a series of astonishing anecdotes: a woman who healed her completely disabling chronic pain by visualizing it; a man who tamed his Parkinson’s disease with exercise; and others who overcame blindness, severe brain injury, and other profoundly impairing conditions by using non-invasive laser or electrical brain stimulation.

The stories are compelling, and the author cites studies on the individual techniques used. However, many of the patients are uncommonly driven, which matters because many of the techniques described require intense, time-consuming, long-term, and repetitive practices. The ones that don’t involve such exhausting exertions tend to use dubious technology. For example, the laser technique seemed promising at first but does not live up to its anecdotal presentation as a way to restore function in severe brain injury.

What we have here is old-time new-age nonsense in a new bottle: neuroplasticity is basically a repackaging of “mind over matter”: You, too, through sheer will or via a few lights pointed at your head, can go from being devastatingly ill to completely cured.

If we can truly understand what neuroplasticity can and can’t do — and why it’s not always good—we could gain insight into treating chronic pain and mental illness.

This is not to say that the anecdotes don’t offer hope that in some cases, the brain can repair itself. Often it can be done by intensely repeating a new behavior. Such stories are real, and such cases need to be studied. But these types of recoveries have always been seen on occasion, even when the brain was thought to be relatively rigid.

If we can truly understand what neuroplasticity can and can’t do—and why it’s not always good—we could gain insight into treating many medical problems from chronic pain to mental illness.

This sounds dicey

A slippery definition of neuroplasticity plagues Your Brain Knows More than You Think, by the psychologist Niels Birbaumer. Parts of the book are devoted, admirably, to debunking the idea that people with severe disabilities like “locked in” syndrome, who cannot communicate or move, should be assumed to have no quality of life. Birbaumer works with such patients and says many of them, once they have been taught to communicate by focusing on certain thoughts to signal intent, describe normal moods, even happiness, and do not desire to end their lives. Nonetheless, these patients are still paralyzed and have to communicate slowly and inefficiently. While neuroplasticity can allow them to learn to communicate, it certainly isn’t a cure or even restoration to health. Their brains are not demonstrating a great ability to change and recover.

Later in the book, Birbaumer tries to present evidence that a brain can unlearn psychiatric disorders like phobias and post-traumatic stress disorder. But he over-promises while promoting some ethically questionable (to say the least!) tactics.

For instance, Birbaumer relays an anecdote in which he drives “like a maniac” in an attempt to help a traumatized man who had been in several serious auto accidents and was, quite unsurprisingly, afraid of driving. During the first of these wild rides, the patient “vomited and evacuated the contents of his bowel and bladder onto my upholstery.” According to the author, this extreme “exposure therapy” eventually allowed the man to resume driving himself.

There are forms of exposure therapy that involve facing one’s fears to retrain the brain, and they can be effective for some phobias and some cases of PTSD. But to avoid actually worsening these conditions, exposure is done slowly, and the intensity is very gradually increased, with the patient always being given the maximum sense of control over the situation.

Given that patients are being asked to repeatedly confront their worst nightmares, even when it’s done gradually this therapy has enormously high dropout rates. Indeed, some patients are actually re-traumatized and they get worse. Yet no cases of failure are presented in the book.

All this is a reminder that plasticity is complicated and often elusive. And it has to be: fundamentally, being plastic—but only up to a point—is what the extraordinarily complex brain does.

How to rewire

Caroline Williams’s My Plastic Brain and Mo Costandi’s Neuroplasticity make this clear. (Costandi is a proto.life contributor.) Neither is a book of miracle cures or tales of superhuman persistence or endurance. Instead, both provide insight into the way plasticity constantly affects our lives.

In some instances, it’s helpful that the brain rapidly tries to automate sequences of behavior. This is how you learn to play music or ride a bike or understand a new language, all tasks that can be done at nearly any age, though it’s easier when you’re younger.

The plasticity that allows this, however, comes at the expense of later plasticity, once a skill has been learned. Bad habits are harder to undo than to establish in the first place. This is why addictions, depression, and other mental illnesses flourish. Once the brain repeats a series of actions often enough— whether it’s taking a drug to cope, ruminating on a distressing thought or becoming anxious in social situations— these, too, can become automatic reactions, easy grooves for the brain to slip into.

Some chronic pain seems to be a rogue form of plasticity, too. In these syndromes, a false signal may get amplified to the point that it continues to repeat and reinforce itself, long after the original source of the pain is gone.

Think of plasticity from a developmental perspective. Early in life, when the brain is most plastic, templates that shape our reactions to later experience are set. If your infancy and childhood are traumatic, your stress system will be wired very differently. If you then discover as a teenager that taking drugs helps you cope, not only will breaking out of that pattern be extremely difficult, but you also haven’t made templates for other ways of coping.

It’s not impossible to make new templates, however. It’s just that the amount of repetition needed to produce learning increases tremendously once a sensitive period when the brain is most open to specific kinds of learning, such as infancy or adolescence, has passed. It will take much, much more repetition of new skills in order to produce lasting changes in behavior. Recognizing this should shape how we treat these problems: expecting something like an addiction to change almost instantly, without time for serious repetition of new skills, is unrealistic and can be extremely demoralizing. Similarly, someone with brain injury or stroke needs as much physical therapy as possible as early and as often as possible. Recognizing how much repetition is required is important. Otherwise, the slowness of change will make the work seem futile.

Psychedelic drugs like LSD and psilocybin seem to affect plasticity, which is part of why interest in therapeutic uses of these substances is growing.

Understanding the chemistry that allows plasticity is also important. Exercise, for instance, seems to increase the release of nerve growth factors that allow the brain to rewire. It can be extremely helpful in diseases like Parkinson’s, though it can rarely stop its progression. Interestingly, antidepressants also affect plasticity: they may actually allow a brain that has been stuck in a problematic groove to jump out of it. Drugs like Prozac have been shown to help people recover function after stroke, an effect that is believed to result from these medications’ influence on plasticity. But they cannot work on their own. They can allow plasticity, but plasticity doesn’t occur if there isn’t an experience to elicit it.

Psychedelic drugs like LSD and psilocybin also seem to affect plasticity, which is part of why interest in therapeutic uses of these substances is growing. Here, too, the drug itself is primarily a catalyst: the way people interpret their experience matters in determining how they change as a result.

We’re only at the beginning of our understanding of neuroplasticity, but just a basic sense of how it functions has already brought new insight into medical and psychological treatments that involve learning, not just taking a pill. Neuroplasticity can be harnessed in other new ways, too—so long as we don’t keep our minds so open that our brains fall out.

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