Why The ‘Chemical Imbalance’ Theory of Depression Is Meaningless
We’re all familiar with Mr. Cruise’s remarks on the subject; and many of us have dismissed him as a lunatic. I won’t argue that he’s fallen off the deep end, but even the most delusional sometimes stumble onto a kernel of truth.
The chemical imbalance theory is a tautology; a prime example of circular reasoning:
In logic, begging the question is the term for a type of fallacy occurring in deductive reasoning in which the proposition to be proved is assumed implicitly or explicitly in one of the premises.–Wiki
So here’s the statement: Depression is caused by a chemical imbalance of serotonin (chronically low levels).
The problem: Low levels of serotonin and depression are the same thing. The above theory would be much like claiming that the sky is blue because light of shorter wavelength is scattered most by the atmosphere. Yes, it’s a true statement. But it says nothing substantive because it’s merely the same observation from two perspectives (eye and spectrometer). Scattered light in shorter wavelengths looks blue to our eyes. The answer to that question would have to go slightly deeper, saying that shorter wavelength light is scattered much more than longer wavelength light by atmospheric gases. Because shorter wavelength light appears blue to our eyes, the sky thus appears blue.
Low levels of serotonin and a depressed mood are the same thing; neurochemical and behavioral perspectives of the same brain event. I’ll refer back to the picture of serotonergic nerves masterfully executed in MSPaint that you first saw in this post on how SSRI’s work (and why I’m not a fan):
The presynaptic cells are what make and release the serotonin (called the Raphe nuclei). The postsynaptic cells are the ones that are affected by the released serotonin. It’s known that activation of the postsynaptic nerves by serotonin is what makes you feel good, and that when these postsynaptic nerves are not firing, you feel depressed. This is why SSRI’s, which don’t affect cells of the Raphe Nuclei themselves, have a positive effect on mood.
Postsynaptic activity is thus a correlate of mood. Because postsynaptic activity is a function of the available serotonin levels, of course low levels of free serotonin will be seen as depression. One implies the other. Ergo, nothing was said.
Low levels of serotonin thus don’t cause depression, they are depression. Thus Tom Cruise was more or less on the ball when he said that, “There is no such thing as a chemical imbalance in a body.”
No one has, in fact, proven that there is an organic cause of low serotonin levels (i.e. a chemical imbalance) in the brains of depressed people, except for one tiny family in eastern europe with a genetic defect that hampers the activity of their serotonergic (presynaptic, Raphe Nuclei) neurons.
There is thus no evidence that depression is neurological in its cause instead of psychological (although it does present with neurologic symptoms both in the short term and chronologically). Considering how much money is going into depression research, my money is that, in the majority of cases, chronic depression is rooted in maladaptive thought patterns.
Maladaptive thought patterns. We misthink our way to chronic depression. Sorry, that theory just does not explain clinical depression.
1. We know that reactive depression (such as normal grieving due to the death of a loved one) causes neurochemical changes within the brain of a person who (we will assume for this argument) had perfect neurochemical balances in every way before grief set in. We know that in these cases, the symptomatology and (as far as we can tell) patterns of neurochemical imbalances are essentially indistinguishable from those of a person with clinical depression (who has no recent tragedies to account for the depression).
2. We know that the person with a healthy brain usually will spontaneously recover from the reactive depression with no psychiatric or pharmacologic interventions. We know that people with clinical (or, as you phrased it, chronic) depression may stay depressed (or go through recurrent bouts of depression) for years.
3. Which is more likely: clinical depression is caused by maladaptive thoughts that somehow induce neurochemical changes that then mimic reactive depression OR clinical depression is caused by neurochemical changes that mimic reactive depression. The latter is a simpler explanation that also avoids blaming the victim.
In regards to your maladaptive thought patterns theory: It is possible that repeated patterns of thought could cause neurophysiological changes that make a person more susceptible to clinical depression. But, so what? Whether the root cause of clinical depression is genetic, congenital, or environmental, the result is abnormal neurochemistry that usually responds to pharmacologic interventions.
I also believe that you are getting too hung up on “organic” versus “non-organic” (psychological) mental illness. It is an artificial dichotomy that should be discarded. We do not make that distinction in other aspects of medicine: when we do not understand the etiology or pathophysiology of a medical condition we call it “idiopathic;” we do not call it “non-organic.”
Comment by Dr. T — March 7, 2006 @ 7:38 pm
The former honestly seems simpler to me given the incidence of clinical depression and the efficacy of behavioral therapy. Clinical depression and reactive depression share more features than distinguish each other. You say the latter avoids blaming the patient, I say it reduces their feelings of control.
I’m not certified or trained to be anything other than a monkey scientist, but I’ve been a free ear and a shoulder to lean on for years, and in just about every case I can think of, the person has felt a diminished sense of their own agency. Telling them a chemical imbalance is keeping them from feeling happy doesn’t help much. Of course you’re not going to walk around saying “You weakling, if you were more of a MAN, you wouldn’t be depressed.” But it does allow you to say “Well, this ain’t fun. But there’s some stuff we can do to make life go a little smoother.”
Actually, understanding the root cause of depression is exceedingly important to developing the proper treatment methods. If, as I believe, the abnormal neurochemistry is a symptom or a result of disease processes occuring at another level, we’re treating depression the wrong way.
I’m not a doctor yet, but I’m pretty sure that when possible we should treat the underlying cause of the disease, rather than cover up the symptoms. And I’m not saying that antidepressants have no role in medicine, because clearly a big part of what doctors do is make people feel better. Sometimes, as in the case of my nerve damage, alleviating symptoms is all they can do. Still, I’m just naive enough to believe that if we can help our patients to leave our offices not only happier and healtheir, but stronger, individuals, we have a duty to do so.
However, I think we need to be clear when we’re alleviating symptoms and when we’re actually fixing what broke. And the efficacy (and arguable superiority, such as here) of behavioral therapy methods in terms of both reduction of depressive feeling and reducing the likelihood of relapse make me wonder.
And again, I’m not sure it’s so artificial. One of the most amazing things about the human brain is its ability to change its own rules of synaptic firing as it goes along. The ability of thought to change neurochemistry, anatomy is well documented. As is the ability of cellular changes to affect thought. There should be a way to distinguish between the two; I’d want to treat someone with that Eastern European family’s genetic defect a lot differently than I’d treat someone with a more typical (and more responsive to cognitive therapy) patient.
Comment by Marmoset Man — March 7, 2006 @ 10:24 pm
There is little evidence that the primary cause of clinical depression is psychological. There is much more evidence that the primary cause of clinical depression is neurophysiological or neurochemical.
Behavioral therapy works in depression by helping the patient cope with the disease. Since most clinical depressions dissipate over time, learning how to cope with the “blues” is a useful technique. However, it also fails to fix the underlying cause.
Antidepressant drugs use brute force to readjust some of the neurochemical imbalances seen in clinical depression. It is unlikely that they are addressing the underlying cause, but they certainly work.
Cognitive therapy works in a small percentage of clinically depressed patients, usually those who have identifiable psychological disruptors in their pasts (such as abandonment by a parent or chronic physical or psychological abuse during childhood). It does nothing for clinically depressed patients who do not have a damaged psyche.
Comment by Dr. T — March 9, 2006 @ 7:19 pm
there must be some serious selection bias going on in the studies i’ve read then, since most seem to find little to no differences in efficacy of the various therapies, usually with lower recurrence rates for CBT. If you can find me one that isn’t, (and also isn’t funded by a major pharmaceutical company( I’m all ears). I literally just haven’t seen one.
Also, in my (albeit limited) experience, you don’t meet people who are depressed for no reason. I’m no Freudian, and my opinion on this is likely to change as I go through med school and residency. But what I see are people who are more prone to become depressed than others. Which is a horse of a different color. I have a strong history of adult-onset diabetes on both sides of my family. Would you argue that I, by extension, have it? Didn’t think so. But I AM more likely to develop it later on. However, there is something I can do to prevent it. And I do.
Most depressed people i’ve met have a reason for being depressed. This might not be an event or an interpersonal relationship, it might simply be their way of looking at themself, could be anything.
Lastly, if my master’s thesis had had as many holes in it as current theories of the origins of depression, I’d have been laughed out of the program. I’m simply applying the same criteria to this research that I had to apply to my own far more inconsequential work.
It’s ok to say ‘we don’t know’. And ‘this alleviates the symptoms’, and ‘but its not really a cure’. I heard all of those plenty when I developed Complex Regional Pain Syndrome. It didn’t bother me in the least. In fact, it made me trust my doctors more when I knew they were willing to admit what is only surmised or assumed, versus what is known.
Comment by Marmoset Man — March 9, 2006 @ 8:18 pm
[...] I’m sure I’m going to catch a lot of flak from status-quo doctors for my arguments (as usual). But just as in the whole depression mess, if you gave me a theory that wasn’t so full of holes it looked like swiss cheese, I might be a little more inclined to accept your contentions. Might. [...]
Pingback by OK so I’m not really a cowboy. » Blog Archive » ADHD: Is it Really a Disease? — March 17, 2006 @ 3:28 pm
[...] Maslow’s heirarchy, Piaget’s theory of child development, the psychiatric ‘chemical imbalance’ theory of depression(click on my psych or medicine categories to see more of my rants about the unscientific nature of psych), all of these are still at the pre-science stage. Their original paradigm has been assaulted by anomalies regarding the purpose of the brain (they evolved for a reason that probably had nothing to do with helping us to ‘achieve happiness and harmony’), the environment the brain operates best in (the traditional classroom is not an environment in which we’d expect what when all is said is done is basically a hairless monkey to thrive in), as well as the constancy and adaptability of the brain (unlike your computer’s circuit board, the brain regularly and constantly rewires itself). [...]
Pingback by OK so I’m not really a cowboy. » Blog Archive » The Problem with Psych (Part I) — April 10, 2006 @ 11:08 am
This is so true. As a therapist, I work with people struggling with depression. The ubiquity of pervasive negative thought patterns is absolutely blatant in a group I run for people with depression. Yet making them see it is almost impossible. They have been so indoctrinated to rely on medications, then spend most of the hour, unless redirected, complaining that the medications don’t work.
Thank you for a very relevent and insightful article.
Comment by Kellen — September 8, 2008 @ 11:46 am