Rethinking the “Chemical Imbalance” Theory of Depression

 Written by Helena Lorenz, M.S.W, LMSW

Licensed Master Social Worker

No two experiences of depression are the same. It comes in all kinds of shapes and forms depending on the specific person. For some people, depression can manifest as anger and lashing out, and for others, it can look like unexpected crying jags and difficulty being social. For some, it comes on after experiencing a distinct trauma, such as the death of a loved one, the loss of a job, or a divorce. And still for others, there is no distinct precipitating event at all. In these cases, it appears some of our brains are just wired to experience the continual sting of melancholy and lethargy for no apartment reason at all.

For these folks in the latter group, those whose depression does not appear to have a specified external origin, we have often thought that their symptoms were due to chemical imbalances in the brain – specifically, a lack of serotonin, the multi-purpose neurotransmitter thought to be responsible for mood regulation. In fact, our most common medicinal treatment for depression, SSRIs, work expressly to artificially increase the levels of serotonin in our brains (think of your most common anti-depressant medications like Lexopro, Zoloft, Prozac, etc).

However, late last year, a groundbreaking new paper rocked the collective worlds of psychology, psychiatry, and neuroscience. It stated, in no uncertain terms, that current research could find no significant causal connection between serotonin deficiency and depression. AKA – we have no evidence that low serotonin levels in the nervous system result in symptoms of clinical depression. I will pause now for the collective *gasp*.

This startling conclusion was determined by what’s called a systematic review, which is essentially the gold standard of scientific investigation. Researchers gathered data from thousands of individual studies, all of which pursued a single hypothesis from a variety of different perspectives. The data are then aggregated and run through various statistical analyses, and we are left with, ideally, the most accurate and well-substantiated conclusions from all the current research on a given subject. In other words, this study is highly trusted and regarded as the new standard of our understanding.

Now I think it’s important to clarify something that can often get confused here. Some people have read the conclusion of this study – that low serotonin does not cause depression - and made the leap that it means that SSRIs do not actually work to help depressed individuals feel better. This is not the case. Study after study has shown that SSRI’s do result in a significant decrease in depressive symptoms as compared to a placebo. As one helpful scientist put it, just because your body isn’t chemically lacking aspirin, doesn’t mean that adding aspirin to your system isn’t helpful when you have a headache. Increasing the amount of serotonin in our system does appear to be helpful, but the lack of serotonin in our system doesn’t appear to hurt. And we simply haven’t figured out why yet! Which sounds potentially nerve-wracking to those of us who are trying in earnest to treat our own depression or the depressions of others. However, I’m choosing to see it as an exciting new place of exploration.

The brain is a fascinating, scary, mysterious, magical place and we are just barely scratching the surface of our understanding of how it operates. And after this paper, we know a smidgen more than we knew before, and tomorrow, we will know a smidgen more than that. Science, like all progress, is a day-by-day adventure.

If you’re struggling with depression, contact us to see how depression therapy can help.