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Neuroplasticity and Depression

The brain changes throughout adult life through a process of plasticity.

Key Concept #1: Neuroplasticity

Throughout life, our brains are continually remodeling themselves, based on experiences, behavior, genes, and so on. It's obvious that our brains keep changing, because otherwise how could you learn to play the drums or master your new iPhone?

In psychiatry, though, we doctors are only beginning to understand how neuroplasticity is involved in the development of psychiatric disorders—and recovery from them. I trained in the 1980s and 1990s, and frankly, back then we never gave much thought to the ways in which the brain was affected by depression or by our treatments. We focused on treating "symptoms" and "disorders" with medication or psychotherapy, but didn't have any sense of whether these things had an effect on our patients' brains.

Plus, hadn't we all learned in junior high school biology that we were born with a certain number of brain cells and that as we got older, they started to die? A knock on the head, a few too many beers, and you'd lose more brain cells. The best you could do was to try to slow the damage.

In the past decade, it has become clear, however, that the brain keeps remodeling itself throughout life. One amazing discovery is that parts of the brain (such as the memory center, called the hippocampus) keep growing new brain cells even in adult life. Another finding is that disorders like depression and anxiety cause damage to the brain, or a kind of "negative plasticity." Other research suggests that treatments of depression and anxiety can actually slow this damage, and possibly even stop and reverse it.

But the take-home message of the New Neuropsychiatry's understanding of neuroplasticity is that your day-to-day behaviors can have measurable effects on brain structure and function. One of my favorite examples is a study that University of London researcher Eleanor Maguire did of British taxi drivers. To get a London hack license, you have to memorize the map of the city of London—a massive project that takes many months. Prospective cabbies ride bicycles through the old city's tangled streets, trying to memorize an incredibly complex map. What Maguire found in a fascinating study published in 2000 was that there were physical changes in the hippocampi of London taxi drivers—with the greatest enlargement in those who had been driving the longest!

Similar studies have been done with people learning to juggle, and with medical students in the preclinical years of training, when they memorize huge quantities of facts about biology, chemistry, anatomy, etc. Such changes to specific brain areas happen quickly, in a matter of weeks to months.

So what? How is that relevant to depression or anxiety?

Obviously only a small percentage of us cram biochemistry texts into our brains or attempt to memorize the routes of hundreds of city streets. But studies of neuroplasticity have spread through psychiatry like wildfire, and have begun to have a huge impact on treatment of depression, anxiety, schizophrenia, substance abuse, and all the other major conditions treated by psychiatrists.

Researchers are enthusiastically conducting studies, trying to find ways to interrupt "negative neuroplasticity" that occurs in many psychiatric disorders, and to find ways to "induce positive neuroplasticity" in treatment of these disorders. In some studies the goal is to increase activity of particular areas of the brain, such as the anterior cingulate (a key decision-making area) or the prefrontal cortex (a location of planning), or to decrease the activity of other areas, like the brain's fear center, the amygdala. In other studies, the goal is to actually get parts of the brain (like the hippocampus) to regrow.

In brief, we have realized that neuroplasticity, the ongoing remodeling of brain structure and function, occurs throughout life. It can be affected by life experiences, genes, biological agents, and behavior, as well as by thought patterns. Interestingly, exercise and physical activity in general have a major effect on neurotrophic factors—chemicals that stimulate the growth and recovery of brain cells.

In thinking about neuroplasticity, a patient I call "Hannah W." comes to mind. She is described more fully in Heal Your Brain, but in brief, she presented for treatment as a 27-year-old single woman who had a difficult early life with many losses and traumas, and who had experienced over 15 years of severe depression and panic disorder. She also had a number of stress-induced medical illnesses including colitis and severe asthma.

Her depression and anxiety responded to medicine and psychotherapy, but to me, the more interesting thing was that at a certain point she became passionate about yoga. She practiced yoga on average 2 to 3 hours a day, and after a few months, she described how she was able to feel a sustained sense of calm and well-being for the first time in her life. For what it's worth, her asthma and GI symptoms became much less severe, perhaps a result of her physical changes.

I don't have MRI scans for Hannah W., but I'm willing to bet that treatment—and her regimen of intense yoga—caused measurable changes in her brain. Specifically, I think yoga allowed her to decrease the activity of her brain's fear center, the amygdala. I'd love to have anatomical and functional MRI scans of Hannah's brain to study what in the New Neuropsychiatry era has become what my colleagues at Columbia call a "researchable question." The fact is, we now have the tools to study the effects of treatment and behaviors like yoga on the brain—on the brain's anatomy and the function of specific centers.

For people with depression and anxiety disorders, I think the New Neuropsychiatry question has started to become, is it possible to interrupt processes of "negative neuroplasticity" associated with these disorders? And through treatment and changes in behavior, is it possible to 'induce' a process of "positive neuroplasticity"? In brief, is it possible to heal your brain?

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