We know a lot about how depression works, and we know a little–though not as much as we’d like–about how to treat it. However, we still don’t know what causes depression, and there are many strong disagreements in the medical and research communities as to where depression comes from, or even how to classify and think about therapy.
Psychology Today is a great resource for different perspectives on mental illness; many of their contributors write blogs about a specific perspective or aspect of an illness. This post is based on blog posts by Christopher Bergland, who writes a blog about the connection between mental health; Emily Deans MD, who writes from the perspective of an evolutionary psychologist; and Gregg Henriques, Ph.D., whose blog wants to create “a unified approach to psychology and philosophy.”
Mr. Bergland and Dr. Deans approach depression as a disease, located in the body; Professor Henriques looks at depression of a symptom of larger philosophical problems in the sufferers’ life. These approaches aren’t mutually exclusive, and neither of them is a definitive “solution” to the problem of the causes of depression, but they may provide complementary ways of thinking about the illness.
Depression in the Body
The popular idea that depression is caused by a “chemical imbalance in the brain” is very vague, and creates a false impression. Many people are led to think that antidepressant medications “re-balance” the brain in the same way that a vitamin supplement resolves a vitamin deficiency. The truth is much more complicated.
At the same time, the biology of the brain is definitely involved in the way depression affects people. You’ve probably seen images showing how a depressed brain looks different than a healthy brain–the healthy brain is “lit up” while the diseased brain is “dark.” Some parts of the brain actually shrink in size as depression progresses–and are restored when depression ends.
Research increasingly suggests that inflammation–the way our bodies respond when we get a cold, or are exposed to something we’re allergic to, or get a burn. This can happen at a low level throughout our entire bodies or even in the tissue of the brain.
The chemistry of our bodies can influence inflammation, and can also be influenced by our lifestyle choices. Both Mr. Bergland and Dr. Deans implicate a chemical called kynurenine in the inflammation that causes depression, and suggest different ways to fight it. Mr. Bergland points out that exercise converts kynurenine into kynurenic acid, and so regular exercise can reduce inflammation. This is one reason why exercise is a helpful treatment for depression.
Dr. Deans talks about reducing inflammation through diet, by changing your fat intake. Many people cut fat out of their diet for the wrong reasons–a high-fat diet generally doesn’t lead to weight gain–but eating healthier fats may make a difference. “Omega-3” fatty acids–mostly found in fish–reduce inflammation, while “Omega-6” fatty acids–found in vegetable oil and many other fat sources–can increase inflammation. Fish oil supplements are safe for most people and can be found in many supermarkets and pharmacies.
Depression as a Behavioral Response
Professor Gregg Henriques has a very different view of depression; he isn’t convinced by these neurochemical viewpoints. In what he calls the “Behavioral Shutdown” theory of depression, he says that people are generally depressed because their lives aren’t going the way they like.
In the Behavioral Shutdown model, depression is an immune response from the brain that spins out of control and proves unhelpful in our modern environment. Think of a bear that hibernates for the winter. The bear hibernates because its body knows that it wouldn’t be effective to forage for food during winter. If the bear was out and about, it would lose heat very quickly and fail to find food, so it might as well stay in and wait until spring.
Similarly, you can think of depression as being triggered by a sort of “emotional winter”–a time when the brain finds that it isn’t being rewarded enough for the effort it’s putting in. Sometimes, these triggers are obvious. Very poor people, and women in abusive relationships, are susceptible to depression because they suffer under immense emotional burdens and often aren’t receiving any emotional rewards in return. But it can also be more subtle, like a period of increased stress at work, or a time when you feel more distant with your established emotional connections (as when children leave their families and friends to go to college). In either case, the brain reacts by creating a state that discourages sufferers from seeking out emotional attachments or pleasure. Depression primes you to avoid situations where you could fail, embarrass yourself, or just expend a lot of energy for no reward.
This doesn’t mean that people shouldn’t ever be treated for depression using medication, according to Professor Henriques–but it suggests that you and your mental health professional shouldn’t be looking at your brain at the root cause of the problem. Instead, you should try and decrease your emotional work/reward ratio to convince your brain to wake up again. This isn’t too different from Behavioral Activation Therapy, in that it depends on your ability to make a change in your life, even if your brain is telling you not to. Seek out positive relationships and gratifying hobbies, and seek to remove sources of stress that you don’t need. If you want to get past the winter, look for an emotional spring.
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