What causes depression?
Can't they just "snap out of it?"
The brain is divided into regions or "control centres" that direct every activity of the body. I have attempted to illustrate these regions in Figure 1. These control centres work independently of conscious thought to automatically regulate your body. For example, your pupil size is adjusted continuously by one of these control centres, yet you have no control over it whatsoever.
In the movement control centre, nerve cells communicate with each other and with muscle cells to create movement. This process is initiated by a thought of intention to move a limb. The nerve cells in the movement intention region of the brain send a command to the nerves cells which connect to the muscles to carry out the movement. If there is any kind of nerve damage or chemical imbalance in the movement control nerves, there will be no transmitted signal nor will there be movement. Nothing will move even though there may be a very strong intentional thought to move the limb. This is the situation after a stroke. The intention to move is there but nothing moves due a nerve injury.
You only have voluntary control of your limbs if all your nerve cells are working correctly to give you that control in response to a thought of intention. If any nerves in the chain of command are not functioning correctly, nothing moves regardless of the intensity of the intention.
This situation can be illustrated if you consider a high performance sports car fueled and ready to go. The highly skilled driver takes his seat, pulls out his maps and waves to the crowd who is encouraging him on. The conditions for driving are perfect. When the driver attempts to pull out of the driveway he discovers that the steering wheel is not connected to the wheels. How far is he going now?
How far can you go without a steering wheel?
In this scenario, there are very strong intentions but nothing happens since there is an internal invisible problem that takes control of the vehicle away from the driver.
It is important to realize that forming a thought is as physical an event as blinking an eye or moving your arm. Nerve cells in the brain allow you to form thoughts in the same way that they permit movement. We only have full control of our thoughts when all the nerve cells are working properly to give us that control. This process is subject to malfunction like any other part of the body. We can lose voluntary control of our thoughts if we have an internal neurological malfunction or an imbalance of nerve transmitter chemicals even though we may have the best of intentions to control our thoughts.
The mood control centre which is illustrated in figure two and three, is a place in the brain where thought content and thought speed is regulated. This centre controls what you think about and how fast you think about it. It therefore controls mood and concentration. We don't know where it is located in the brain since it is more of a function than a location.
If your nerve cells are working correctly in this location, your mood and concentration will always be kept within the normal range. It is impossible to measure mood but we define normal mood as being relaxed, content, feeling in control, concentrating normally, clear headed and coping with stress. I'm not sure that I know anyone this normal, they would likely stick out from the population and be very dull. When the control centre is functioning well, your mood will always eventually return to the normal range regardless of the degree of negative stress which would be depressing or positive stress which would be exhilarating. It works much like a top or gyroscope which will always return to the vertical position as long as it is spinning.
Mood Control Centre
Figure 2
The Mood Control Centre should maintain mood in the normal range
regardless of circumstances.
There are very specific chemical substances called neurotransmitters which are produced by brain cells to regulate these control functions. If anything happens to disrupt the production of these chemicals, then the control centre will malfunction and mood will fluctuate outside of the normal range and you will lose the ability to control your thoughts. If for example, there is a chemical imbalance, you would find your thoughts going much faster and it would be harder to control what you were thinking about. If something positive happened, your thoughts could race uncontrollably in excitement or if something bad happened you could race with depressive thoughts. You would lose the ability to put brakes on the thoughts.
It is now well established that mental illnesses are usually the result of an imbalance in the chemicals associated with mood control. This tendency to malfunction is usually inherited. Symptoms may just appear without reason or depression may come as a result of stressful circumstances that bring out the inherited tendency to have a mood disorder. As a result of the discovery of the above facts, depression is now seen as a physical illness needing and responding to medical treatment.
Due to the genetic nature of the condition, a triggering stress is not always needed. Sometimes depression just develops over years with no obvious cause. There is no doubt however, that stress can trigger a depressive illness in someone who already has the genetic potential for depression. If there is very strong genetic potential, then it will take very little stress to trigger an illness and symptoms may appear at an early age. If the genetic link is weaker, then more stress is needed to cause disability and the condition may not appear until late in life if at all.
The treatment of depression is the same whether or not it was triggered by stress. If the chemical imbalance is present, it can be treated regardless of the cause. Think of it this way. If someone breaks their leg, they will need a cast. It doesn't matter if it was caused by a fall or a car accident, the treatment of the resulting disability is the same.
When the chemical imbalance is corrected, the person is then better able to deal with their stresses since their thought control has been restored.
The text of this section contains excerpts from "Healthy Moods".
Illustrations by Rev. Jim Keddy
For more information visit Answers to common mental health questions.
Copyright Dr. Grant Mullen. No part of this website can be reproduced without the written permission of the author and publisher.
