The Stress-Depression Link

In the last few articles in my series on antidepressants and depression, I have presented evidence demonstrating that – despite popular belief – depression is not caused by a deficiency of serotonin in the brain.

However, this of course does not suggest that depression is completely divorced from biochemical processes in the body.

The brain is a “living orchestra” of complex, interconnected systems that are in continuous relationship with one another. Everything from the food that we eat to the chemicals we’re exposed to in our environment to the hormones we produce effects the functioning of the brain. This will likely come as no surprise to you. It’s simply common sense. But as you may have noticed, in the world of scientific research common sense must first be proven according to the established standards of scientific proof before it is accepted.

Such has been the case with the link between stress and depression. I’ll wager that if I asked ten people on the street whether chronic stress caused depression, probably all ten of them would say “yes”. However, scientific proof of the causal link between chronic stress and depression has only begun to emerge over the past few years. It has been known for much longer that depressed people have elevated levels of cortisol (an indicator of chronic stress), but it was not known whether those elevated levels were the result or cause of depression.

In 2006 Ardyfio & Kim published a study indicating that chronic hypercortisolemia (elevated cortisol levels in the blood) causes anxiety-related behavior in mice. These results suggest that elevated cortisol levels may contribute to the symptom profile of depression rather than simply being a consequence of it.

Ardyfio & Kim’s study also confirmed the results of other studies which suggest that while acute stress is adaptive (helps us adjust to our changing circumstances), chronic stress has detrimental effects on the brain and behavior. Indeed, chronic stress has been linked to a wide variety of modern diseases, including (but not limited to) heart disease, cancer, diabetes, autoimmune disease, irritable bowel syndrome and fibromyalgia.

In a more recent study published in 2007, work stress was demonstrated to precipitate diagnosable depression and anxiety-related disorders in previously healthy, young individuals. The authors point out that stressful work conditions predict poor mental health, and that currently as many as 40% of people are exposed to work stress. (That’s funny, I would have thought the number to be closer to 100%).

The relationship between psychological job demands and the risk of depression and anxiety was graded; in study members exposed to high psychological job demands the risk was two times higher than in those with low demands. The combination of multiple work stressors conferred an even higher risk, especially in men.

Once again, this probably does not come as a surprise to you. It makes sense that high stress at work may cause depression and anxiety. But, believe it or not, this is relatively recent news to the mainstream scientific establishment.

Finally, in a study published today, researchers have shown how cortisol (one of the stress hormones) regulates brain neurotransmission in both the short and long term and enables neuronal connections to adapt.

This behavior is adaptive, as it helps the organism (us) prepare and mobilize for action when faced with stress (a threat).

However, in the case of prolonged stress (which is the type of stress most prevalent in modern life) cortisol actually reduces synaptic plasticity. Lack of receptor mobility contributes to a lack of adaptation, which of course, is bad news for us.

The relevance to all of these studies to our recent discussion about depression and its treatment is this: stress is likely a significant contributing factor to depression for most people, and stress-management should play an important role in the treatment of depression.

In short, there is absolutely no reason not to include stress management in your treatment regimen for depression, or in your daily life even if you are currently healthy and free of disease.

There are many ways to reduce stress, including meditation, prayer, gentle movement (yoga, tai chi, Feldenkrais), exercise, deep relaxation techniques, spending time in nature, listening to music. What’s most important is that you find something that works for you and stick with it.

Mindfullness-Based Stress Reduction (MBSR), created by Dr. Jon Kabat-Zinn, is a very successful approach that has been clinically proven in well-designed studies to reduce pain and stress and improve health. I recommend his book Full Catastrophe Living, as well as the CD recordings of the techniques.

I also recommend a system of gentle movement and breathing exercises called “mini-moves”. Although they are marketed as a treatment for insomnia, the creator (Michael Krugman) of the system believes (quite correctly) that the best way to cure insomnia is to manage daytime stress successfully. You can download the “Secrets of Sounder Sleep” audio here. They are very simple and can be performed in as little as 5-15 minutes at a time.

I’ve used both of these systems myself with great success.

Next week will be the final article in the depression series (for now): drug-free alternatives to treating depression. Until then…

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