How does Chronic Stress Lead to Depression?


A threat to your life or safety triggers a primal physical response from the body, leaving you breathless, heart pounding, and mind racing. From deep within your brain, a chemical signal speeds stress hormones through the bloodstream, priming your body to be alert and ready to escape danger. Concentration becomes more focused, reaction time faster, and strength and agility increase. When the stressful situation ends, hormonal signals switch off the stress response and the body returns to normal.

So, the stress is good for humans.  It keeps us alert, motivated and primed to respond to danger.  As anyone who has faced a work deadline or competed in a sport knows, you can understand that stress mobilizes the body to respond, improving performance. 

However, at the stressful conditions of the modern society, too much stress, or chronic stress may lead to major depression in susceptible people. Many of us now harbor anxiety and worry about daily events and relationships. Stress hormones continue to wash through the system in high levels, never leaving the blood and tissues. And so, the stress response that once gave ancient people the speed and endurance to escape life-threatening dangers runs constantly in many modern people and never shuts down.

Research now shows that such long-term activation of the stress system can have a hazardous, even lethal effect on the body, increasing risk of obesity, heart disease, depression, and a variety of other illnesses.

How it works?

The HPA axis is a feedback loop by which signals from the brain trigger the release of hormones needed to respond to stress. Because of its function, the HPA axis is also sometimes called the “stress circuit.”

Briefly, in response to a stress, the brain region known as the hypothalamus releases corticotropin-releasing hormone (CRH). In turn, CRH acts on the pituitary gland, just beneath the brain, triggering the release of another hormone, adrenocorticotropin (ACTH) into the bloodstream. Next, ACTH signals the adrenal glands, which sit atop the kidneys, to release a number of hormonal compounds.

These compounds include epinephrine (formerly known as adrenaline), Norepinephrine (formerly known as noradrenaline) and cortisol. All three hormones enable the body to respond to a threat. Epinephrine increases blood pressure and heart rate, diverts blood to the muscles, and speeds reaction time. Cortisol, also known as glucocorticoid, releases sugar (in the form of glucose) from the body reserves so that this essential fuel can be used to power the muscles and the brain.

Normally, cortisol also exerts a feedback effect to shut down the stress response after the threat has passed, acting upon the hypothalamus and causing it to stop producing CRH.

This stress circuit affects systems throughout the body. The hormones of the HPA axis exert their effect on the autonomic nervous system, which controls such vital functions as heart rate, blood pressure, and digestion.

The HPA axis also communicates with several regions of the brain, including the limbic system, which controls motivation and mood, with the amygdala, which generates fear in response to danger, and with the hippocampus, which plays an important part in memory formation as well as in mood and motivation. In addition, the HPA axis is also connected with brain regions that control body temperature, suppress appetite, and control pain.

Similarly, the HPA axis also interacts with various other glandular systems, among them those producing reproductive hormones, growth hormones, and thyroid hormones. Once activated, the stress response switches off the hormonal systems regulating growth, reproduction, metabolism, and immunity. Short term, the response is helpful, allowing us to divert biochemical resources to dealing with the threat.

The Stress-Depression Connection

Chronic s tress, such as taking care of a terminally ill family member at home, or sharp and severe, such as losing a job or the death of a loved one -- can lead to major depression in susceptible people.  Both types of stress lead to over-activity of the body's stress-response mechanism.  

Sustained or chronic stress, in particular, leads to elevated hormones such as cortisol, the "stress hormone," and reduced serotonin and other neurotransmitters in the brain, including dopamine, which has been linked to depression.  When these chemical systems are working normally, they regulate biological processes like sleep, appetite, energy, and sex drive, and permit expression of normal moods and emotions. When the stress response fails to shut off and reset after a difficult situation has passed, it can lead to depression.

This theoretical assumption has been confirmed by the several clinical studies. One of the recent researches, conducted on mice, corroborated the theoretical assumption that a long-term exposure to cortisol may actually contribute to depression development. The mice were exposed to acute (24 hours) and chronic (17 to 18 days) doses of the rodent stress hormone corticosterone, putting it into their drinking water.

The mice with chronic exposure, in comparison to those with acute one, took longer to go out of small dark compartments into a brightly lit open field, a common test for anxiety in animals. Those with chronic exposure were more fearful and less willing to explore their new environment, also not showing normal reactions when being startled, another indication that their nervous system was overwhelmed.

Researchers noted that people with Cushing's disease, when too much cortisol is released, suffer depression and anxiety and those receiving corticosteroid therapy for inflammatory conditions also have mood problems.

Learned Helplessness and Clinical Depression

In studying how stressful events may lead to depression, researchers have developed a theory called, "learned helplessness." This theory states that when people experience chronic or repeated stressful events, they learn to feel helpless. This feeling of helplessness is strengthened when a person believes he or she has no control over the stressful situation. Although the research to support this theory was initially done with animals, the effects of learned helplessness may be seen in depressed humans.

People who are depressed very often have negative beliefs about their ability to manage aspects of their lives based on perceived failures in the past. For example, imagine an adolescent girl living in a home with verbally abusive parents who tell her that she is stupid and cannot do anything right. Over time the young girl may believe her parents and come to doubt her abilities and self-worth. She may begin to feel helpless and believe that most things are beyond her control. This feeling of helplessness may make her vulnerable to developing clinical depression at some point in her life.

How to deal with chronic stress?

There are multiple suggestions for relieving from stress negative consequence you can find online. There is no point to remove stress from your life completely, since you cannot regulate the external conditions and life events. But you can adapt your body to handle these stressful life conditions without losing the grounds, being able to manage successfully inside the reasonable response to the external life. One size does not fit all, and you need to find your own mental relaxers and guards.

There are few popular suggestions:

1.       Adopt a pet. Interaction with pets is relaxing and may therefore aid in stress management. Pet therapy is acknowledged approach to reduce stress. But be careful to chose this method, as adoption a pet requires taking responsibility for this creature life and well-being. Are you ready for that?
2.       Apply Positive Self-Talk. Self-talk is one way to deal with stress. We all talk to ourselves; sometimes we talk out loud but usually we keep self-talk in our heads. Self-talk can be positive ("I can do this" or "Things will work out") or negative ("I'll never get well" or "I'm so stupid"). Negative self-talk increases stress. Positive self-talk helps you calm down and control stress. With practice, you can learn to turn negative thoughts into positive ones.
3.       Use Emergency Stress Stoppers. There are many stressful situations — at work, at home, on the road and in public places. We may feel stress because of poor communication, too much work and everyday hassles like standing in line. Emergency stress stoppers help you deal with stress on the spot. Try these emergency stress stoppers. You may need different stress stoppers for different situations and sometimes it helps to combine them.
·         Count to 10 before you speak.
·         Take three to five deep breaths.
·         Walk away from the stressful situation, and say you'll handle it later.
·         Go for a walk.
·         Don't be afraid to say "I'm sorry" if you make a mistake.
·         Set your watch five to 10 minutes ahead to avoid the stress of being late.
·         Break down big problems into smaller parts. For example, answer one letter or phone call per day, instead of dealing with everything at once.
·         Drive in the slow lane or avoid busy roads to help you stay calm while driving.
·         Smell a rose, hug a loved one or smile at your neighbor.
4.       Find Pleasure. When stress makes you feel bad, do something that makes you feel good. Doing things you enjoy is a natural way to fight off stress. You don't have to do a lot to find pleasure. Even if you're ill or down, you can find pleasure in simple things such as going for a drive, chatting with a friend or reading a good book.
5.       Relax. Relaxation is more than sitting in your favorite chair watching TV. To relieve stress, relaxation should calm the tension in your mind and body. Deep breathing is a form of relaxation you can learn and practice at home using the following steps. It's a good skill to practice as you start or end your day. With daily practice, you will soon be able to use this skill whenever you feel stress.
·         Sit in a comfortable position with your feet on the floor and your hands in your lap or lie down. Close your eyes.
·         Picture yourself in a peaceful place. Perhaps you're lying on the beach, walking in the mountains or floating in the clouds. Hold this scene in your mind.
·         Inhale and exhale. Focus on breathing slowly and deeply.
·         Continue to breathe slowly for 10 minutes or more.
·         Try to take at least five to 10 minutes every day for deep breathing or another form of relaxation.
6.       Watch TV. It was proven that the simple watching of television can reduce the level of stress a person can carry at a moment, and it can lower the anxiety level. This is very helpful in the matter: how does stress lead to depression. Also, a very important thing to know is that watching television for a very long period of time, or watching low-quality programs, that our personality rejects sub-consciously, can lead to stress build up, and this is bad for our body and mind, even if it looks like we are enjoying the viewing.
7.       Get to Fitness. In general, physical exercises proved to be an efficient and easy-to-perform, approach for stress reduction. Some of such activities might be especially effective, such as meditation, yoga, dancing, or water related procedures.
8.       Get Massage. Another way to get rid of stress is to go get a massage, when one goes to massage therapy, one can effectively relax muscles, ease muscle spasms and pain, increase blood flow in the skin and muscles, relieve mental and emotional stress, and induce relaxation.
9.       Write about it. Many people claim that self-assessment in written form helps to put the stress factors in proportion and assists in dealing with them. Write self-evaluation, email to a close friend, or start a blog. While writing is not able to substitute the professional consultation, it does help to ventilate the feelings and develop an action plan on how to deal with stressors.
10.   Get enough sleep. Lack of rest just aggravates stress. Adequate sleep fuels your mind, as well as your body. Feeling tired will increase your stress because it may cause you to think irrationally.
11.   See a Doctor. If your stress management efforts aren't helpful enough, see your therapist. Do not wait the moment when depression will penetrate full speed in your mind and body.

How NOT to Deal with Chronic Stress

Some of the coping strategies may temporarily reduce stress, but they may also cause more damage in the long run:
  • Smoking tobacco.
  • Drinking too much alcohol.
  • Overeating or undereating.
  • Zoning out for hours in front of the TV or computer.
  • Withdrawing from friends, family, and activities.              
  • Using pills or drugs to relax.      
  • Sleeping too much.
  • Procrastinating.
  • Filling up every minute of the day to avoid facing problems.
  • Taking out your stress on others (lashing out, angry outbursts, physical violence).

Sources and Additional Information:


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