Chemical imbalances

I am writing today to address an old rumor about brain chemistry and mental illness that still seems to be hanging around. For some reason that I can't fully comprehend, though I am pretty sure it has to do with some clever antidepressant marketing and the way that science is often communicated to the “general public”, some time in the late 90s people started to discuss the "fact" that mental illness is caused by chemical imbalances in the brain. And, it was suggested that giving a medication (namely, antidepressants) could balance your brain chemicals out, thus curing your mental illness. It is confusing where this "conclusion" arose, though I can assure you it was not from science, or psychiatry. In fact, the American Psychiatric Association (APA) never stated anything of the sort, and they are the ones who labor in committees of experts for days and days to come up with "consensus" ways of communicating scientific information about mental illness to the public as a whole. Now, don’t get me wrong, I don’t think everything the APA does is correct, but in this case I think they were.

There is some new research in this area that is very interesting, and we'll get to that in a bit. But, for the most part, the only clue that brain "chemicals" are involved with depression, anxiety, mania, psychosis, etc. comes from observations of what happens to various animals (including us) who are exposed to drugs that alter the levels of said chemicals. For those of you with a scientific background, you are probably already thinking, "Hmm... That sounds like a correlation that does not necessarily imply causation, and says nothing about what occurs in a natural system", and you would be exactly right. Knowing what happens when an unnatural level of a chemical is introduced to a living system, says little about what effects that chemical has in it's natural state. As for causation-- that can really only be understood if the mechanism is understood. And, even now, with all the sophisticated means we have developed to study functional neurophysiology, the mechanism is quite poorly understood.

The chemicals in questions are the monoamines, primarily serotonin and norepinephrine. It does seem to be the case that having low levels of these molecules in your central nervous system and in certain parts of the brain predisposes you to have difficulty with mood regulation and anxiety. However, there is no proof that the deficiency of these molecules is the cause of depressive episodes, manic episodes, anxiety, psychosis, etc. The reality is much more complex— an interplay between genetic differences in how our bodies produce and regulate those chemicals important in our mood system AND our psychological makeup that develops over the course of life experiences.

Another argument against the “chemical imbalance” stance is that antidepressants don’t tend to “restore” normal levels of monoamines. They actually cause very high, abnormal levels that sometimes (slightly more often than placebo) has a therapeutic benefit for depression, anxiety, mania, etc.

I mentioned some interesting new research. Functional imaging techniques (mostly f-MRI) allow researchers to look inside the brain at how different types of neurons and regions of the brain are functioning in response to various conditions. There is evidence that neurons in regions of the brain responsible for emotion (and those dependent on monoamines) function less well in people with mood disorders, and the functioning can be improved by some of the existing pharmaceuticals. Also, there is now evidence that epigenetic changes (changes in gene function and expression due to external factors) may occur in the setting of childhood adversity that alter the way our monoamine receptors function later in life. This is the missing link that will help us understand how “psychological” factors can impact the functioning of brain cells.

It is also important to note that in a system where serotonin is not well-produced, or is not functioning properly, neurons don’t grow/repair/connect as well, due to the neurotrophic, or nerve cell growing, importance of serotonin. So, we have every reason to believe that child abuse/neglect/bullying and all forms of hate, cruelty, emotional stress and trauma that we encounter has the ability to affect the growth and repair of brain cells.

To summarize, it is not a chemical imbalance that causes mental illness. Emotional illnesses do seem to be caused, at least in part, by a poorly functioning monoamine system due to both genetic and epigenetic factors and by an impaired ability of brain cells to grow, connect and repair. Are these changes in nerve function fully responsible for depression, insecurity, self-doubt, attachment issues and low self-esteem? Perhaps, or perhaps there are aspects of our psyche that cannot be reduced to changes in nerve function and chemical concentrations. Resolving this issue will no doubt continue to challenge the limits of human understanding for the rest of our existence.