Is depression caused by a chemical imbalance?
First, we must establish what we mean when using the word, “depression”. Depression has many faces. It feels different to different people, as there are many causes and many subtypes of depression. Some people experience a depressed mood as the result of a situation or event in their lives that produce profound sadness. This is sometimes referred to as “situational depression”, and with a properly functioning brain, one can process the loss and feel good again. The same can be said of bereavement and the grief experienced as the result of losing a loved one. For the purpose of this article, we will talk about Major Depressive Disorder (MDD). MDD is defined as having a depressive episode that lasts for at least two weeks. Unfortunately, most people experience a depression that lasts for months or years. Symptoms usually include:
Major Depressive Disorder is now considered to be an illness of the brain. But can it be explained as a simple imbalance of brain chemicals? No.
Major Depression involves many more aspects of brain function than just the levels of chemicals. Neuroscience has uncovered innumerable physiological abnormalities in the structure and function of the brain. They are too numerous to list here. The major type of cell used by the brain for information processing and communication is the neuron (nerve cell). The chemicals used by one neuron to communicate with another neuron are called neurotransmitters. These include serotonin, dopamine, and norepinephrine. There are more, though. The exchange of neurotransmitters is only one of the ways in which neurons communicate with one another. There are even ways in which a neuron communicates with itself within the cell. However, these aspects of Major Depressive Disorder are rarely conveyed to the public. Instead, MDD has historically been explained as a simple chemical imbalance in order to make it more understandable, and to emphasize that the illness is biological in origin. It seems that the public may have outgrown this teaching tool. MDD can also be made understandable by thinking of the brain as a bunch of computer processors connected by a network of circuits. The routing of circuits between brain structures is more important than which neurotransmitters are being used.
More recently, a problem has resulted from the continued use of the term, “chemical imbalance” to explain to the public the biological origins of Major Depressive Disorder. Because scientists have determined that MDD is not a disorder caused exclusively by chemical imbalances, some people have jumped on this statement in order to pursue their agendas to claim that MDD does not have any biological components at all. While it is true that an episode of Major Depression can be triggered by a situational depression or other psychosocial stresses, this is only possible if there are any pre-existing genetic or other biological vulnerabilities. In other words, just because MDD is no longer thought of by scientists to be the result of a simple chemical imbalance does not mean that there are no other biological processes responsible for it. There are. MDD can also be made understandable by thinking of the brain as a universe of neurons acting like computer processors connected by a network of circuits. The routing of circuits between brain structures is more important than which neurotransmitters are being used. So the next time someone tells you that depression is not biological in origin because the chemical imbalance theory has been proven wrong, you will understand that there is faulty logic involved in coming to this conclusion.
Blog posts are written by Shore House members and staff.