Stress-Depression Connection Coming To Light

Stress-Depression Connection Coming To Light

Vijai P. Sharma, Ph.D

Current research is casting new light on the biological connection between stress and depression. Continued ongoing stress can cause depression even in a young child. Once a link between stress and depression is formed, that child may be prone to depression for the rest of his or her life.

Such a link may lie dormant for decades only to surface as a result of chronic stress or as an acute reaction to a traumatic life event.

This may explain why children, whom we ordinarily expect to be carefree and happy, can suffer from depression and develop a life-long tendency to become depressed. Children reared in a toxic environment experience an extraordinary level of stress and may, therefore, exhibit symptoms of major depression during early childhood.

Although we don't know everything about what causes depression, we know enough to dismiss the catchall, non-specific and non-descriptive cause referred to as "chemical imbalance." We have to look further and ask ourselves, "What causes chemical imbalance after all?"

Medical research has so far provided a partial explanation, "The mood chemicals cause imbalance; too little Serotonin and too little Norepinephrine,." But, researchers are developing new insights into the biological connection, which traces it back to chronic and intolerable levels of emotional stress. Let's first look at the biological explanation of chemical imbalance.

We have known for sometime that stress produces stress hormones. Adrenal steroids secreted during stress reach the brain and over time can affect brain structures.

When stress hormones, intended for an emergency, remain switched for a long time they can slow the growth of nerve fibers in the areas of the brain responsible for emotions and memory.

More specifically, stress hormones can destroy and slow the growth of nerve fibers in hippocampus, the part of brain which links experiences to emotions, and then store the memories of these experiences and emotions. Imagine the far-reaching effects of overexposure to stress hormones on the brain of a child which is still growing.

Brain imaging studies show that the hippocampus is typically small in the depressed patients with a number of cells destroyed or shrunken. Experts believe that shrinkage and partial destruction of nerve cells in the hippocampus is central to depression.

There is further evidence that intensive negative emotional experiences can alter the structure of other parts of the emotional brain as well. Individuals with post-traumatic stress disorder show enlargement of the amygdala, which is the brain's "alarm system." The job of the amygdala is to screen the environment for potential threat. Neurons in the amygdala start firing as it senses a threat, and this process begins even before we become conscious of the threat.

Considering that the amygdal's job is to watch for danger, it's not surprising that the amygdala of a traumatized person becomes enlarged. It is enlarged because it is continuously overexcited and overworked. Having experienced trauma once, it senses danger even when there is no danger.

Stress affects different people in different ways. Not all children develop depression from continued emotional distress. Some develop anxiety or other emotional and behavioral disorders while others grow to be resilient and emotionally healthy adults.

Of course, genetic factors play an important role in the incidence of depression. But, genes simply render a person more vulnerable to depression or other emotional disorders. Genes alone don't produce depression; they do it with the help of negative and stressful experiences.

There is a theory in psychology called the "diathesis-stress" model. What it says is that genes predispose a person to certain psychiatric disorders. When the person predisposed in this way experiences a particular type of stress, the disorder may come to the surface.

Theoretically, genetically predisposed individuals who are fortunate enough to never experience a critical level of stress may live their entire lives without ever suffering from the disorder.

If we simply assume that chemical imbalance somehow causes depression, we would fail to recognize the damaging effect of stress on emotional health. Trauma, abuse, or chronically severe stress in a genetically predisposed child can create unacceptable levels of stress chemicals in the brain.

Continued overexposure to stress hormones can alter the physical structure of the emotional brain. The altered physical structure of brain organs may reduce or increase the secretion of the "mood hormones" or neurotransmitters, if you will.

Such a pattern of chemical reactions may be established, resulting in childhood depression. Once the pattern is well entrenched, it lays the groundwork for depression during teenage and adult years. The depression puzzle is far from being solved, but science is a step closer.

Chemical imbalance as an explanation of depression is merely "skin-deep." The cause of depression is deep down in the heart, mind and spirit of the person.

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Copyright 2003, Mind Publications 
Posted December 2003


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