Is Depression Just a Chemical Imbalance?


What is depression?

Major depression is a serious problem for individuals and for society. According to a recent report published by the World Health Organization, major depression is the number one cause of death and disability in industrialized nations. This means that depression causes more problems for society than heart disease or diabetes or HIV or any other single health problem you can think of.

Selling the idea of a “chemical imbalance”

Over the last decade or so, television and print commercials stating that depression is caused by a “chemical imbalance” have become commonplace. It seems that you cannot watch TV anymore without seeing a commercial advertising that some psychological problem is due to a “chemical imbalance.” Unfortunately, this depiction of depression is greatly oversimplified and leaves out many important factors in understanding this problem. While describing depression as due to a chemical imbalance may be useful in helping a drug company sell more of its products (prescriptions for antidepressant drugs increased 148% between 1990 and 1998), this notion can also lead to negative effects among those struggling with depression. Many others have written about this misconception and advertising technique (for a few examples see here and here). The main problem with this idea is that it is disempowering to the individual dealing with the problem, as it can lead to a person believing that there is nothing they can do to deal with their depression beyond taking a pill.

At this point, some readers may be thinking that I am blaming people with depression for being in the predicament they are in, but I am not. The answer is far more interesting than that. Read on to find out more.

Two problems with the idea of a chemical imbalance as the cause of depression

A number of studies have shown that people with depression often have unusual levels of a variety of neurotransmitters in certain parts of the brain. Based on these findings, some people (e.g., drug companies) have concluded that lower levels of particular chemicals in the brain “cause” depression. This conclusion is based on an error in logic. Correlation does not mean causation. It also ignores the heaps of research showing that depression is associated with people’s behavior, with their thinking patterns, and with their history. Depression is at least as correlated with these things as it is with brain chemicals. In terms of brain chemicals, the only conclusive thing we can say is that depression is associated with lower levels of certain chemicals in the brain, not that depression is “caused by” by the levels of those chemicals.

The idea that depression is solely a “chemical imbalance” also does not account for the fact that several forms of psychotherapy have been shown in multiple studies to be just as effective as (and better at preventing relapse than) antidepressant medication. These findings are evaluated in more detail below.

How could psychotherapy be just as effective as medications?

We behave the way we do because our brain reacts in certain ways to our environment. Any new information or changes in our behavior or habits are stored in our brains. In fact, whenever we learn a new way of thinking or behaving, our brain changes to reflect this new behavior. For example, when someone learns to do mathematics problems better, a region of their brain has changed its structure to reflect this new learning. Both the cellular structure of individual neurons has changed as have the levels of neurotransmitters (for some research that shows that exercise, for example, changes the brain’s structure, look at this link).

Events in our lives can teach us to be depressed, and in turn our brain changes in a way that is consistent with acting depressed. As a result of experiences in life, we end up with a brain which reacts in certain depressed ways. Just like our brain changes when we learn to live in a depressed manner, we can also learn live a non-depressed life and our brain will change to reflect that. Consistent with this idea is research which has shown that similar changes are found in peoples’ brains when they recover from depression, regardless of whether this occurred as a result of psychotherapy or medication. In simpler terms, if you change your behavior, regardless of how this occurs, your brain will change. Similarly if your brain changes, your behavior changes.

Thus there may be multiple ways of recovering from depression, including both medication and psychotherapy. In fact, several studies have shown that some forms of psychotherapy (e.g., CBT, mindfulness based cognitive therapy, and interpersonal therapy) can decrease the rates of relapse to depression even after therapy is stopped. This doesn’t happen with medication. With medication, relapse prevention only lasts as long as the medication is taken. Thus, in order to prevent future episodes of depression, a person may need to stay on medication indefinitely.

How does psychotherapy help depression?

Science has not been completely clear on this point yet. But neither do we know why antidepressants help with depression. We just know that they do. Anyone who tells you they absolutely know how psychotherapy helps alleviate depression is trying to sell you something.

Nevertheless, in this author’s eyes, one theory appears particularly promising. This is what is called the behavioral theory of depression, first proposed by Ferster in 1973. This theory holds that depression is the result of a lack of rewarding activities in a person’s life, whether this is due to lack of opportunity (e.g., being trapped alone in a cave) or due to other reasons (e.g., a person withdraws from friends as a result of “not wanting to bring them down”). According to this theory it is the lack of engagement in activities that are truly meaningful and valued that results in depressed feelings. In depression, a person then typically reacts to these depressed feelings by further withdrawal or disengagement with life, which results in exacerbating the depressed feelings.

According to this theory, the problem here is not actually the depressed feelings or thoughts, but rather a person’s reaction to these depressed feelings or thoughts which perpetuates the lack of rewarding activities and keeps the person depressed. Thus techniques which help the depressed person become reengaged in the world are the route to recovery. This is the basic theory behind the type of therapy that we use at the Portland Mood Disorders Clinic. We help people to overcome the obstacles to engagement in valued activities in their life and to not just feel better but also to live better, with more vitality and meaning.

If you need help with depression…

If you think you may be suffering from depression, don’t hesitate to find someone who can help. Studies show that while depression can sometimes go away on its own, often it does not and requires treatment. Other studies show that even if depression were to improve without professional help, it usually improves more quickly with treatment, either psychotherapy or medication or even a placebo. Some people choose to see their primary care doctor for medication. If medication helps, that’s great. Some people find that medication doesn’t help or doesn’t help enough. They may find that side effects are too high of a price to pay. For many people, psychotherapy is a good alternative to medication. Psychotherapy can often be helpful even if medications aren’t.

Some people try psychotherapy first. Some forms of psychotherapy have more evidence for depression than others. Particularly well proven are cognitive-behavioral therapies, interpersonal psychotherapy, and emotion-focused therapies. I’d recommend starting with someone who practices one of these approaches. If they are not helpful, look for other approaches. At the Depression Treatment Program at Portland Psychotherapy, we use evidence based practices in treating depression, which includes cognitive behavioral approaches and emotion-focused therapy.