The Link Between Stress and Depression

Researchers are working on determining a link between stress and depression, making it important for people to find stress relief mechanisms.

Stressful situations are common in our society; from traffic to tough economic times. Luckily the body has a built in stress handling mechanism.

Unfortunately in our society people are faced with stress chronically which has led to higher depression rates. It is hoped that once the relationship between stress and depression is established, more effective stress relief resources can be determined.

The Endocrine and Nervous Systems Response to Stress

When faced with a stressful situation the human body has a built in response called the flight or fight response. The key hormone elicited is adrenaline also known as epinephrine and neurotransmitters like noradrenalin and norepinephrine.

The hormones trigger several systems to prepare the body to face whatever the perceived threats are. The result is increased heart and breathing rate. This serves to ready the body for increased oxygen consumption on the case of flight.

Blood is also diverted from the non essential systems, such as the lymphatic system, stomach and intestines. Blood vessels direct flow to the muscles required for the fight or flight response.

The body also releases nutrients required to sustain muscular activity. The result is a human body that is set for intense muscular effort. The response continues until the threat is resolved. If a person is placed in a chronically stressful environment than the fight or flight mechanism stays activated.

This constant activation can cause a weakened immune system, an over worked heart, a variety of stomach problems and depression. This evidence loosely links stress and depression. Once the stressful situation passes the brain triggers an adrenaline crash which triggers the relaxation response.

Cortisol – The Possible Hormonal Link Between Stress and Depression

An increase in adrenaline levels leads to a gradual increase in cortisol.

Cortisol is another flight or fight response hormone. Unlike adrenaline levels which decrease rapidly after the stressful situation has passed, cortisol levels increase slowly and also decrease slowly. Cortisol stays in the system longer than adrenaline, continually exerting its effect.

Cortisol increases blood pressure and blood sugar levels to aid in the flight or fight response. For a body in a chronic stressful state adrenaline and cortisol are secreted constantly. This leads to among other things the increased levels of fatty acids in the blood vessels (cortisol signals the metabolism of fatty acids to produce and emergency supply of energy).

There are many theories on how the high levels of cortisol can cause depression. The data is still inconclusive. However, data shows that people who have high levels of cortisol are sometimes but not always exhibit symptoms of depression.

The same goes for people with low levels of cortisol sometimes exhibiting depression. There are probably other factors at play namely genetics.

Some experts say that the high levels of cortisol affect neurotransmitters like serotonin, lowering its level. It is commonly known that serotonin is one of the underlying neurotransmitters said to be responsible for depression. Other experts point to the hippocampus in the brain as the source of depression.

The Role of the Hippocampus in Depression

Another theory is based on the destructive nature of cortisol on the hippocampus.

The hippocampus is responsible for learning and memory. Various studies show the relationship between a diminished hippocampus size and depression.

In the treatment of depression the medications taken that help restore the hippocampus function takes 3 to 6 weeks to work. This time frame coincides with the time period it takes to heal an atrophied hippocampus.

The importance of the hippocampus rests in the fact that it is the one of the few places were new nerves are generated (neurogenesis).

In individual exposed to lower stress levels the hippocampus is constantly undergoing neurogenesis, unlike individuals exposed to high stress levels. The exact cause of depression as related to the hippocampus is not understood. The only thing that is understood is that the decrease in the hippocampus size leads to an increase in depression symptoms.

When anti-depressants are taken, they aid in the regeneration of nerves in the hippocampus. This leads to the symptoms of the depression being relieved.


Once the link between stress and depression is established then avoiding depression can be as simple as looking for stress relief resources.

Choosing a healthy lifestyle coupled with exercise and a healthy diet can help build the body’s response to the adrenaline crash which follows the adrenaline rush.

Learning stress relief management techniques can also help individuals avoid stress related side effects.

From Stress and Depression to the main page about Emotional Stress

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