Wouldn’t it be great if you could explain to your severely depressed patient exactly what causes major depression—in five seconds? For example, you might try one of these approaches:
1. Major depression is caused by a chemical imbalance in the brain.
2. Major depression is caused by anger at others, turned inward against oneself.
There—easy, right? The first “explanation”, of course, is a spinoff of the mythological “chemical imbalance theory of mental illness”–which was never a full-fledged theory propounded in the highest echelons of American psychiatry .
The second statement was a psychoanalytic hypothesis that had some currency when I was in residency, and for which there is some (mixed) empirical support. .
In my view, both “explanations” vastly oversimplify the complex causes of depression; indeed, they are both reductionistic. (Dr. Glen Gabbard has pointed out that psychoanalytic interpretations may sometimes be as reductionistic as biological ones; i.e., “Both [psychoanalysts] and their patients secretly are drawn to simple formulations that eschew complexity.”).
But what if we abandon these five-second oversimplifications, and spend, roughly, five minutes with our depressed patients, explaining what we know (and don’t know) about the etiology of major depression?
In my experience, such a five-minute discussion can be fit quite feasibly into a half-hour session. (Contrary to popular lore, the average psychiatric session is not a “15 minute med check”—it is probably closer to a 35 minute meeting ).
As a psychopharmacology consultant for more than 25 years, I saw mostly patients with refractory mood disorders, usually referred by other psychiatrists.
The Funnel and the Bridge
What follows is an idealized dialogue–with annotations for the clinician– similar to the kind I would have when first evaluating a seriously depressed patient. It makes use of two metaphors or visual images that I found very useful, and which my patients seemed to appreciate; namely, the “funnel” and the “bridge.”
I would often hand-draw these images and give the drawings to the patient, as a kind of transitional object-cum-educational device. Here’s roughly how the discussion would go with “Joe” (a composite patient), somewhat modified for teaching purposes:
Patient [“Joe”, a 40-year-old construction supervisor recovering from his second severe major depressive episode]: So, this lousy depression, Doc—what causes it? Is it some kind of chemical thing? Or is it just that I’m weak, or messed up or what?
RP: Well, first, Joe, depression doesn’t mean you are “weak” or “messed up!” People often tell depressed patients, “Just pick yourself up by your bootstraps!” But that’s not fair. Serious depression isn’t a matter of having a weak will or being lazy. We don’t know the exact causes of depression, but there are probably many causes that interact.
Joe: Okay, like what? Bad parents? Bad diet?
RP: Well, most psychiatrists believe that depression has biological, psychological and social causes. If we visualize these three factors coming together at the top of this funnel I’m drawing, then, at the bottom, we have depression as the outcome.
Joe: Okay, but—what do those terms really mean? Is it that chemical imbalance idea or some Freudian thing? And what do you mean by “social?”
RP: It’s way too simple to speak of a “chemical imbalance,” Joe, and there are so many chemicals in the brain, it’s nearly impossible to know what the right “balance” is for any particular patient. That said, we have good evidence that in severe depression, the brain’s internal environment is often abnormal, compared to the brains of folks who aren’t depressed .
Joe: You lost me, Doc! What do you mean, “internal environment?”
RP: Well, Joe, you know that the brain is made up of billions of cells called neurons, right? We think that for many people with severe depression, the neurons in some parts of the brain may not be communicating properly with neurons in other brain regions—some brain “circuits” may be too active while others may not be active enough .
That could be because of a problem with brain chemicals—neurotransmitters–released by the neurons, but it could also mean there’s a problem with the receptors for these chemicals–those little slots where the neurotransmitters land. The receptors might be too sensitive or not sensitive enough.
We also have evidence that growth of new brain cells and the little branches that connect them may be reduced in major depression . In children who suffer bouts of major depression, there may actually be a gradual loss of “grey matter”—basically, brain cells and their branching extensions .
We don’t know exactly how antidepressants work, but they may boost brain cell growth and enhance the branching process . This takes some time, which may be why antidepressants take a few weeks to work. By the way, Joe, there are also lots of medical factors and conditions that can cause, or worsen, depression—like low thyroid function, some vitamin deficiencies, various drugs, and so on. That’s why we checked your labs earlier.
Joe: OK, Doc, so far, this is all biology. So if depression is biological, can people get it from their parents?
RP: Well, it’s not like inheriting blue eyes or blond hair, Joe. But people probably do inherit the tendency toward depression. Your genes—the units of heredity– make proteins that are involved in thousands of biological processes. If your genes are not making the right proteins in your brain, that may increase your risk of depression.
With bipolar disorder—or manic-depressive illness–it’s pretty clear that there is a hereditary factor. For example, if one identical twin has bipolar disorder, the other has a 60% to 80% chance of developing it, too . The hereditary piece isn’t as strong in other types of depression, but…
Joe: Wait a minute, Doc! What about the other 20-40% in the bipolar twins? The ones who don’t inherit the depression? How do you explain that, if they’re identical twins?
RP: So here is where we get into the “psychological” and “social” pieces of the puzzle, Joe. Even identical twins may have different psychological habits. We don’t know for sure if self-defeating, “negative” thoughts cause episodes of major depression or whether they are the effect of a depressive bout. But for sure, the way a person views the world can have a profound effect on mood.
For example, if someone turns you down for a date and you tell yourself that you don’t deserve to be loved or that you will never be loved, you will be setting yourself up for depressive feelings .
If you constantly tell yourself that you must be perfect at everything you do, you are also setting yourself up for feeling depressed. Whether you will actually develop clinical depression probably depends on your genetic makeup and how resilient you are in the face of setbacks and stress—how well you “roll with the punches.” .
To complicate things, depression itself can generate a “negative filter,” so that everything looks grey and gloomy—which leads to more negative thoughts, in a kind of vicious circle. And then, of course, there are all the social experiences, good and bad, that happen to you from childhood on…