Drugs and Talk Therapy Affect the Brain in Different Ways

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Man and his psychotherapist
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Psychiatric drugs and psychotherapy mostly have the same purpose: to make us feel better mentally and emotionally. However, it seems like common sense to assume that they do so by very different means, the former acting chemically on your brain and the latter altering your mind and thoughts. Yet if you ponder this some more and consider that our brains are our minds — after all, every lived thought and feeling has its basis in the brain — it follows that if you spend time on the therapist’s proverbial couch, any benefit will ultimately register not only in changes to how you think, but also in changes at a neural level. The fact is, any kind of psychological technique is associated with brain changes — consider how mindfulness meditation has been linked with shrinkage to the amygdala, a neural region involved in processing emotions. 

This raises an interesting question: Are the brain changes induced by psychotherapy the same or different from those induced by antidepressant medication? A new meta-analysis (the kind of research that looks at results across many previous studies) published recently in Brain Imaging and Behavior looks at this very question in relation to major depression. The researchers, based at several institutions in Italy, say their results suggest psychotherapy and drugs affect the brain in different but complementary ways.

Maddalena Boccia and her colleagues looked at brain-scan results from 38 experiments that involved hundreds of patients treated with drugs (mostly Prozac-like drugs known as selective-serotonin re-uptake inhibitors that work to increase the amount of serotonin available to neurons), and 18 experiments that involved hundreds of patients who undertook psychotherapy (mostly cognitive behavioral therapy, usually abbreviated to CBT, but also including interpersonal therapy and psychodynamic therapy).

The studies that the researchers analyzed generally took the form of comparing patterns of activity in patients’ brains after treatment compared with before treatment. Averaging across these results showed that some of the brain changes associated with drug and psychotherapy treatment were overlapping, but there were also some striking and important differences.

Drug treatments tended to be associated with increases in brain activity in the limbic system and other sub-cortical structures, including in the insula. These areas are broadly associated with emotional processing, and the insula in particular is involved in representing our internal bodily states. Boccia and her colleagues characterized these therapeutic effects as “bottom up” and said they could be related to the alleviation of the psychosomatic symptoms, such as chest pain and fatigue, that are often associated with major depression.

In contrast, psychotherapy appeared to lead to changes to activation patterns in parts of the frontal cortex and temporal cortex — brain areas known to be associated with thinking about ourselves and to storing and processing  memories. The researchers characterized these effects as “top down,” related to how we interpret the world and our place in it, which makes sense given that a major goal of CBT is to alter unhelpful thinking habits.

The researchers said these distinct neural effects of antidepressants and psychotherapy suggest that the two kinds of treatment are not simply doubling up, prompting the same changes by different means. Instead, the brain-scan results suggest the two forms of treatment are having contrasting, complementary effects, one of them altering activity in higher brain areas in the frontal cortex, and the other targeting deeper emotional structures. In the best cases, these effects could reinforce one another: Perhaps someone who has fewer physical symptoms is less likely to slink into a deep depression, and someone with fewer intrusive negative thoughts is less likely to develop physical symptoms.

This idea that drug treatments and psychotherapy have different but complementary effects on the brain is consistent with research showing that depressed patients often recover most successfully when they undertake a combination of psychotherapy and psychiatric medication. For example, there’s research suggesting that complementing drug treatment with psychotherapy can lead to longer-lasting remediation of patients’ symptoms. The new findings also make sense given that the brain areas revealed here as altered by drugs and psychotherapy are the same areas where, according to past research, depressed patients often show abnormal functioning compared with healthy controls. In this sense, medications and talking treatments can be seen as returning different parts of the brain to a mode of functioning that resembles that seen in people who aren’t depressed.

Although these new findings seem to paint a neat picture, it’s important to realize that things get a lot more complicated when you broaden the question to other forms of mental illness. For example, a review published last year of 42 articles found that in the case of obsessive-compulsive disorder (OCD) and panic disorder, psychotherapy and drug treatments appeared to have largely similar effects on the brain. Also, whereas drug and talk therapy for OCD acted to return brain activation patterns to those seen in healthy people (as was also the case for the depressed patients in the new research), treatments for panic disorder did not. You could say that in the case of panic disorder, the brain changes brought about by treatment appeared to be compensatory rather than “normalizing” — the brain didn’t return to its healthy state as such, but other neural changes were brought about that helped offset the difficulties associated with the illness.

Clearly, this is a complicated area of study. And it’s very early days for the field, too. This new research looked at how drugs and psychotherapy altered activation patterns in the brains of depressed patients, but what about changes to brain structure or to the way different brain regions are connected and communicate with each other? It’s also worth noting that many of the studies conducted to date fail to include comparison brain scans of patients on a waiting list for treatment. This means that at least some of the brain changes attributed to psychotherapy could really just be part of the natural course of the illness and recovery from it, rather than a direct result of the process of psychotherapy (a similar methodological problem afflicts research into the effectiveness of treatments for mental illness, since people’s moods and symptoms vary naturally; suitable control groups are always needed to check that patients wouldn’t have gotten better with a placebo or just recovered naturally — possibly even more quickly — without any treatment).

These shortcomings aside, this is an exciting field to watch — with time, although some psychologists and patients may not find the idea appealing, it’s possible we may be able to use brain scans to monitor whether a course of psychotherapy is having hoped-for effects on the brain. Also, finding out more about how talk therapy changes the brain could signpost new directions for drug-treatment research. It’s sometimes tempting to see psychotherapy as a mysterious process, impenetrable to scientific inquiry. But the emerging neuroscience of psychotherapy could generate new clues toward more effective forms of talk therapy, better drugs, and more efficient ways to combine the two — all improving the odds that those who are suffering will get and stay better. 

Dr. Christian Jarrett (@Psych_Writer), a Science of Us contributing writer, is editor of the British Psychological Society’s Research Digest blog. His latest book is Great Myths of the Brain

Drugs, Talk Therapy Affect the Brain Differently