The True Cause Of Depression

About two years ago a patient of mine committed suicide. When his wife, who was also my patient, told me the news at one of her visits, I was shocked. Fully aware that 40% of older patients who are suicidal visit their primary care doctors within one week of killing themselves, I found myself ruminating over and over how I’d missed recognizing the severity of his distress. I’d known he’d been suffering from depression but had thought it mild.


The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) classifies depression into the following types (there are even more, but these cover the basics):

  1. Dysthymia. In essence, having a depressed mood on most days for at least two years.
  2. Major Depressive Disorder. In addition to feeling “down” as in dysthymia, other characteristics may include excessive feelings of guilt and suicidal ideation, as well as various physical symptoms like loss of hunger and fatigue. It can be mild, moderate, or severe.
  3. Adjustment Disorder with Depressed Mood. This is grief due to a loss of some kind (which itself can be classified as normal or complicated).
  4. Depression NOS (not otherwise specified). Includes things like premenstrual depression and seasonal depression (SAD).
  5. Secondary depression. Depression due to an underlying medical disorder like Cushing’s disease or hypothyroidism.

Though not in DSM-IV, some practitioners further classify depression into two broad types:

  • Endogenous depression to denote depression that arises without an obvious identifiable cause, thought to reflect some kind of “chemical imbalance” in the brain.
  • Exogenous  depression which is thought to arise from a specific, identifiable external cause.

Given this confusing and non-parallel classification scheme, it’s astonishing doctors don’t become depressed themselves as they try to figure out into which bucket their patient’s depression fits. How can we make sense of all this and, more importantly, understand the real causes of depression in order to augment the effectiveness of currently available therapies?


First, we need to recognize the distinction between chemical and external depression is becoming outdated. Neuroscientists have good evidence that the mind arises from, and is actually caused by, the physical brain, meaning chemical and electrical reactions somehow give rise to thoughts and emotions. Evidence in support of this theory can be found in numerous studies that show altering brain chemistry with antidepressant drugs (chemicals) can make depressed people feel better emotionally. The same is true for anxiolytics (like Valium) and their effect on anxiety.

But recently, with the advent of functional MRI scans (fMRI), we now have proof the opposite is equally true, that changes in thinking cause significant, measurable changes in brain chemistry and functioning. In one study, patients suffering from spider phobia underwent fMRI scanning before and after receiving cognitive behavioral therapy aimed at eliminating their fear of spiders. Scans were then compared to normal subjects without spider phobia. Results showed that brain function in patients with spider phobia before receiving cognitive behavioral therapy were abnormal compared to subjects without spider phobia but then changed to match normal brain patterns after cognitive behavioral therapy. This may represent the best evidence to date that changes made at the mind level are able to functionally “rewire” the brain, and that the brain and the mind are in reality merely two sides of the same coin, or different ways of viewing the same single thing.


Where, then, does the true cause of depression lie? In the context of the critically important caveat that clinical depression is almost certainly more than one disease with more than one proximate cause, I would hypothesize that in most cases depression arises at its core from a belief that we’re powerless to solve our problems.

This is clearly true with people who know why they’re depressed: invariably, once they figure out how to solve their particular problem, their depression lifts. But I would also argue this often—though by no means always—holds true for people who are depressed for no reason they know as well. Why? Because thoughts can trigger feelings that remain stirred up long after the thoughts themselves have been forgotten. Some studies have suggested people think upwards of 12,000 thoughts per day. How could we ever remember them all? Yet a fleeting thought we might have had this morning about the possibility of losing our job can and often does leave an emotional residue that lasts hours, days, weeks, or even longer. I would argue, therefore, any depression that appears to be “chemical” may in fact be caused by a thought that simply isn’t remembered—a thought about a problem we don’t believe we can solve. (On the other hand, many psychiatrists describe have depressed patients who tell them their lives are “just fine” but that they’re depressed anyway. To tell if such people are depressed because of unrecognized cognitive distress or because of some non-cognitive abnormality is extremely difficult. If such patients never successfully identify a cognitive distortion as the true cause of their depression does that mean it never existed or they just never found it?)

Further, sometimes what appears to be a “chemical” depression is caused by a thought that isn’t directly or consciously recognized. These thoughts are often about problems that seem so unbearably awful and unsolvable we literally don’t want, and often refuse, to think about them (such as our becoming jobless or the prospect of our own death).


None of this is by any means to say we can simply decide to believe we can solve a particular problem when no solution is obvious or forthcoming. Changing any belief, whether consciously recognized or not, is one of the hardest things to do in life. But armed with a hypothesis of the true cause of depression we can consider the following steps to help ourselves:

  1. Find a way to raise your life-condition. Your inner life state has more to do with your ability to believe you can solve your problems than anything that may be actually going on in your life. If your thoughts are swirling in despair, take action to break free of them and attain a fresh perspective. Become immersed in a great book that moves you or watch a movie that transports you. Exercise. Go where it’s warm. Meditate. In short, do what you know from experience bounces your thinking to a more optimistic place.
  2. Identify the problem or problems you don’t think you can solve. It’s amazing how often you don’t know why you’re depressed and how helpful it can be to figure it out. Making a list of everything that’s bothering you—a sort of stream-of-consciousness rant on paper—can be a fantastically helpful exercise. Or if you do know why you’re depressed, recognizing the cause isn’t that you have a problem per se but rather that you have a problem you don’t believe you can solve can be remarkably empowering. Also, sometimes we become depressed not because we have one problem we believe we can’t solve but because we have multiple problems we believe we can’t solve. Handling challenges can be likened to balancing a “plate” of a certain size: if we pile too many problems onto it, not only do we risk having it topple over, we often find ourselves wanting to pitch the whole thing on purpose. When this is the case, allow yourself to only worry about and focus on solving one problem at a time.
  3. Identify the reason a problem seems unsolvable. As I pointed out in a previous post, Changing Poison Into Medicine, many things erroneously cause us to conclude we’re deadlocked, chief among them our inability to identify a solution to our problem right now.
  4. Recognize that your thoughts are profoundly influenced by your mood. Once depression has established itself, it takes on an insidious life of its own, further diminishing your belief in your ability to solve problems, your ability to plan, and your ability to have hope for the future.  In this way the cause of any depression always reinforces itself.
  5. Remember that your depressed self is not your true self. Whatever life-condition you find yourself in at any one moment always feels like the only life-condition you’ve ever had or will have. But your life-condition can and often does change literally from moment to moment.
  6. Understand that antidepressants only treat the symptoms of depression. None of the foregoing has been intended as a denial that antidepressant medication plays a significant role in the treatment of depression. In the right patient, antidepressants reduce the symptoms of suffering exceptionally well and can be literally life-saving. Research is especially clear that combining antidepressant medication with cognitive therapy is more effective than either alone. But antidepressants can’t make anyone actually happy because happiness isn’t merely the absence of suffering. The best approach might be to treat the symptoms of depression with antidepressants (or cognitive therapy or even electroconvulsive therapy) when symptoms are severe enough to warrant it while at the same time attempting to address the underlying cause of the depression itself.

I fully recognize that as a means to battle depression—especially a deep, all-consuming depression—these suggestions are inadequate. The point in making them, however, is to emphasize that the single most effective means to resolve a depression is to find a way to tap into our immense power to solve problems.

Sign up to get notified when a new blog post has been published.