There’s a reason depression can be so difficult to treat: Scientists are still figuring out exactly how and why it strikes.
Different treatment methods impact the brain in drastically different ways, and in a new article in Nature, Emily Anthes explores why therapy and drugs sometimes work — and sometimes don’t.
Depression doesn’t just give you a temporary case of the blues. It’s linked with physical changes in the way the brain works.
Two major areas of the brain bear the brunt of those alterations: the prefrontal cortex, which sits behind the forehead and extends about a quarter of the way back on the head, and, below that, the amygdala, a nugget-shaped chunk of brain.
Antidepressants, often considered the go-to treatment for people with depression, target only one of those problem areas — the amygdala. That could help explain why just 22% to 40% of people with depression get full relief from antidepressants.
Cognitive Behavioural Therapy — a very specific type of talk therapy — appears to affect the other area, the prefontal cortex.
Both regions seem to be key players in depression. While the prefrontal cortex helps us exercise self-control, which we need to avoid dangerous bouts of negative thinking, the amygdala helps us process emotions, allowing us to feel joy, anger, and sadness.
In healthy people, the prefrontal cortex checks the amygdala, keeping us from constantly getting so upset we punch a wall or so sad we can’t stop crying. People with depression likely have an under-active prefrontal cortex, which takes away the natural check-and-balance system, and an overactive amygdala, which makes them more prone to sweeping emotions.
Since it appears to stimulate the prefrontal cortex, the thinking goes, cognitive behavioural therapy could help depressed people who don’t respond well to antidepressants.
Research backs up this idea. Two recent randomised, controlled trials (the highest study standard used to evaluate a method of treatment) that included close to 600 people in all found cognitive behavioural therapy to be a useful, cost-effective alternative to antidepressants. Another, much smaller study found that, when compared to people who stopped taking antidepressants, people who stopped cognitive therapy were less likely to plunge back into full-fledged depression, meaning the treatment could have longer-lasting effects than traditional medications.
Scientists still don’t know exactly what goes wrong in the brains of people with depression. While many depressed people experience similar symptoms — from constant feelings of worthlessness to distorted, unrealistically negative views about the world — the underlying mechanisms that cause those symptoms can vary from person to person.
As a result, people with depression respond differently to different treatments. While antidepressants can be a miracle cure for some, cognitive behavioural therapy — or a combination of both therapy and antidepressants — might work better for others.
Training The Brain
People undergoing cognitive behavioural therapy sit down with a therapist who guides them through their own thoughts. When a bout of negative thinking crops up, the therapist has the patient talk it out.
Say, for example, that I tell my therapist I feel I did a bad job at work. I didn’t write enough stories, I say, compared to my co-worker, Joe, who seemed like he wrote a ton.
The therapist would have me tell her how many stories I write each week, how much time I spend on each story, and how I feel about the quality of each story when I look back on them. Then I’d see that in reality, regardless of how many stories I write, I’m proud of them and put my best effort into each one. In other words, I don’t need to feel bad. I’m doing just fine.
Arriving at this conclusion myself is important because I’ll be able to practice the technique later on without needing the therapist’s help.
Putting these mental coping skills into practice does far more than merely change the way we think. It also appears to change the way the brain works, at least enough for the difference to be measured on an MRI. A 2007 study, for example, found that a small group of depressed adults with overactive amygdalae and under-active prefrontal cortices could reverse the imbalance in their brains with 14 weeks of cognitive behavioural therapy.
Still Not A Perfect Solution
Scientists still have a long way to go to successfully treat and cure depression. The gaps in our knowledge about how the brain works make it nearly impossible to develop perfect treatments. And while cognitive behavioural therapy shows promise, we still have too few studies, many of which are too small to draw definitive conclusions.
Another major challenge is that we can’t yet predict who will respond to antidepressants and who will respond to therapy. For now, treatment remains a trial-and-error process that can be long and painful.
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