How Therapy Changes the Brain

Oct 09, 2023

brain , neuroscience

Advances in neuroscience allow us to see the profound and broad impact of therapy more clearly
Neuroscientist Dr Camilla Nord explores some of the ways therapy changes the brain
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Therapy can profoundly alter someone’s emotions, thoughts, and behaviours— and for many people, substantially improve their mental health. What sometimes gets overlooked is where the effect of therapy originates from: changes inside the brain.

Our brain is shaped by our experiences, which gradually and physically alter the brain to construct a representation of the world around us. By changing what we experience, psychological therapy also changes our brains. Through this process, therapy has the capacity to change complex cognitive processes, like our beliefs about the world.

It’s much more common to cite the brain effects of antidepressant medication, and other treatments traditionally considered “biological”. But I argue in my recent book that in fact all mental health treatments are biological. For well over a decade, many neuroscience studies show that psychological therapies have clear, measurable effects on the brain. The brain effects of therapy occur at many different levels: from changing neurochemicals such as serotonin to increasing the volume of the hippocampus (a region involved in memory and learning) and strengthening connectivity between different parts of the brain.

How does a therapy session alter the brain?

I’ll use one type of therapy as an example: exposure therapy. Exposure therapy works by gradually introducing a patient to something they find fearful or a source of anxiety. Exposure might occur over several sessions in a structured therapeutic environment—it even works in virtual reality. Exposure therapy can successfully treat conditions ranging from spider phobia to post-traumatic stress disorder and social anxiety.

Over time, exposure causes changes in the brain’s learning circuitry, eventually extinguishing previously-held fears. At the molecular level, these changes depend crucially on synaptic plasticity mechanisms of the brain, such as the brain’s N-methyl-D-aspartate (NMDA) receptors.

In one recent study, I compared changes in the brain that occurred after a course of various types of psychological therapy with changes in the brain after several weeks of antidepressant medication. We discovered that antidepressants changed brain activity in the amygdala, a region involved in perceiving and experiencing emotions. In contrast, psychological therapy changed brain activity in a region called the medial prefrontal cortex, which has a different, higher-level role in emotion, mediating your attention and awareness of your own emotional state.

The fact that psychological therapy and antidepressants target different areas of the brain implies they may be working via slightly different routes. But although anatomically-separate, these two regions have something in common: they both fall in what is sometimes called the brain’s “affect network”, a pattern of areas involved in your sense of feelings and emotions. So although antidepressants and psychological therapy might have distinct effects on the brain, they also cause common, overlapping changes. These changes could contribute to their mutual ability to improve mental health.

Maybe this is interesting, but is it useful? Our current gold-standard therapies still fail to treat almost half of patients with anxiety and depression. A better understanding of how psychological therapy works could help us understand why it works for some, but not others.

One futuristic-sounding idea is to match patients to the right treatment using brain scans. For example, some research suggests that a patient’s brain activity can predict which treatment they are most likely to respond to. So, an MRI scan could tell us whether an individual patient would be a better candidate for mindfulness-based therapy, or selective serotonin reuptake inhibitors. (Note brain scans are costly, but they are certainly less expensive than a long course of therapy for someone who would not benefit.)

There’s another potential benefit to knowing how therapy affects the brain. Scientists are using this information to develop augmentations— add-on interventions to enhance the brain effects of therapy. This could be another route toward improving therapy’s effectiveness. For example, brain stimulation has been used before or during therapy sessions to boost the function of regions of the brain known to be involved in therapy (some of these combinations have worked, some haven’t). And rather than simply combining long-term medication with psychological therapy, new drug approaches are using single doses of medication given just before a therapy session to enhance the effects of that particular session. For example, a number of studies report that combining exposure therapy with drugs that target the NMDA receptor to facilitate fear extinction is more effective than exposure therapy alone.

Capitalising on what we know about therapy’s biological mechanisms could give new combination treatments a leg-up. In a recent paper, we found that short-term augmentations delivered before, during, or after various different types of therapy sessions improved response compared to non-augmented therapy. Some augmentations were particularly powerful – psychedelics and related drugs had a large effect on psychological therapy outcomes (a topic also explored in a recent Welldoing article). This could be a targeted way of improving therapeutic responses by finding the right combinations of therapies and augmentations.

Could timing therapeutic sessions with your circadian rhythm harness what we know about the interactions between circadian rhythm and the brain’s learning system? Or what about scheduling therapy sessions immediately after exercise, which is also known to have effects on neuroplasticity?

These and other augmentations are still in development, and neuroscience has a long way to go to make this possible—but it starts with understanding the crucial role of the brain in therapy.

Dr Camilla Nord is the author of The Balanced Brain: The Science of Mental Health