ABC Radio National’s Health Report recently did a fascinating program on neuroplasticity: Brain plasticity / Measuring brain plasticity (for those who don’t want to listen to the audio there is also a link there to the transcript of the program). I highly recommend this program which outlines some exciting new implications of research into the workings of the human brain.
Our brains are not like computers, which have a fixed hardware onto which you load software and that stores information by re-arranging some ones and zeros electrically. For one thing, the transfer of information in our brains uses a highly complicated combination of electrical and chemical signalling. More significantly, though, as we form new memories and learn new skills our brains actually change structurally. Neuroplasticity is the ability your brain has to change structure – to “rewire itself” in response to experience. This is a slow process in adults – taking place over weeks, months and years in many cases – but essential to how we learn. In babies it is a far more rapid process – as the Radio National program explains.
In depression the story is often told that the disorder arises from a “chemical imbalance in the brain”. The most commonly-told story is that depression is a result of insufficient serotonin.
However, the scientific evidence shows this is not true. The “chemical imbalance” idea arose from the serendipitous discovery that substances that increase serotonin seem to help improve symptoms of depression. But research that has tried to confirm the simple “less serotonin = more depression” hypothesis has repeatedly discredited the theory. New discoveries are pointing instead to a role played by brain structure. Authors of a 2003 paper in Biological Psychiatry, Enhancing neuronal plasticity and cellular resilience to develop novel, improved therapeutics for Difficult-to-Treat depression, write:
…although most antidepressants exert their initial effects by increasing the intrasynaptic levels of serotonin and/or norepinephrine, their clinical antidepressant effects are only observed after chronic (days to weeks) administration, suggesting that a cascade of downstream effects are ultimately responsible for their therapeutic effects.
Later in their paper they also note:
…recent evidence demonstrating that impairments of neuroplasticity and cellular resilience may underlie the pathophysiology of mood disorders, and that antidepressants and mood stabilizers exert major effects on signaling pathways that regulate neuroplasticity and cell survival, have generated considerable excitement among the clinical neuroscience community and are reshaping views about the neurobiological underpinnings of these disorders.
These new directions in the theory of depression (which extend to other psychological conditions, as well) make more sense clinically than the old “chemical imbalance” ideas. If disorders are caused by chemical imbalance, what caused the chemical imbalance? Why do those with depression so consistently describe combinations of life circumstances that triggered their initial symptoms of depression if the cause of their depression is purely chemical? Neuroplasticity, on the other hand, both helps us to understand how psychological problems develop and how they can be treated.
If you have known someone with moderate to severe clinical depression you will likely be familiar with the seemingly “stuck thinking” that occurs in a person with depression. It does feel like a depressed person’s brain is functioning differently: it is like the depressed brain is unable to process positive experiences and can only take in information that is negative – further feeding into the person’s low mood and feelings of dejection and guilt.
Among the many implications of neuroplasticity for treatment is the role of repeated exposure over time. For example, one of the studies reported in the Radio National program describes 40 hours of exposure to video games over 20 days producing benefits to eyesight in adults. Structural changes in our brain take time. If undertaking any therapy that involves retraining patterns of thinking (an important component of Cognitive Behavioural Therapy, for example) it is important to allow enough time for conscious, deliberate adjustments to thinking to become part of our automatic cognitive processes.
Among many the interesting points covered in the Radio National Health Repport program, I was particularly interested in mention of the relationship between neuroplasticity and exercise:
So one of the most effective types of intervention that one can do to improve your brain power is actually to exercise your body. And there’s very good evidence that particularly as we get older and our brain powers decline, one of the best ways to guard against that is to keep the body active and in particular to engage in cardiovascular activity which works the body.
Once again, the importance of exercise in mental health is reinforced.
Image source: Wikimedia Commons