Saturday - Jun 19, 2021

Stress or Depression: What is the Missing Link?

stressed woman

We all experience stress at times which can be put down to a part of living a modern life, but the onslaught of depression is a much more serious condition.  It is known that a traumatic incident can cause stress which eventually could trigger a depressive disorder if not medically addressed.  This is what compelled researchers to conduct studies in mice in order to understand the brain processes and mechanism that can compel stress to depression.

The results of the study were published in Nature International Journal of Science. The researchers from the University of Washington identified the missing link as a peptide which they called corticotrophin-releasing factor or CRF.  They believe that CRF plays a role in the nucleus accumbens, an area of the brain known to stimulate motivation, social behavior, and pleasure.

How does the Missing Link Work?

The brain is composed of billions of nerve cells that work together through nerve signaling.  In a normally functioning brain CRF is released when something motivating or exciting happens, for example, you receive a gift or an award.  This CRF binds to the receptor in your brain, causing an increase in a chemical called dopamine which is responsible for making you feel happy or rewarded. 

The Scientific Experiment

The researchers conducted a standardized experiment known as conditioned place preference : they put a mouse in one of  two cages  connected to each other.  CRF was then infused to the nucleus accumbens of the mouse.  Then they moved the mouse to the second cage and a placebo liquid was infused.

The scientist wanted to find out which of the two cages the mouse would prefer?  As  they had suspected, the mouse chose the cage where it received CRF, even though the cages were identical.  The scientist then confirmed their theory that when the mouse was exposed to the cage where it received CRF, dopamine was released which is the 'feel good chemical’  

In the second stage they created a central experiment wherein they stressed out the mouse until  it eventually showed signs of depression.  The researchers went on to test if CRF  still had an effect of causing dopamine release after the mice was stressed,  but they were surprised to note that the CRF no longer had any effect. When the cage test was repeated after the mouse was stressed, it was found that CRF had a complete opposite effect, the mouse didn’t chose to spend time in the cage where it received the CRF, proving that the molecule had become ineffective.

The research team observed that the effect lasted for almost 90 days which is actually the same for humans suffering a major depressive disorder.  This means that the pathway that helped to motivate the mice became the culprit in making them deteriorate.

Understanding the Implications of the Missing Link

The scientific studies paved the way for more experiments to be conducted to help to understand the implications of the missing link.  Major Depressive Disorder also known as  Clinical Depression is considered  one of the most common and debilitating type of mental disorders.  It has a significant impact on a person’s quality of life, causing constant anxiety, sadness, loss, anger and in extreme cases may cause hallucinations and delusions. 

Stressful and traumatic life events like death of a loved one, accidents and many other unfortunate events can trigger the onset of Major Depressive Disorder (MDD).  This hideous disorder impedes a person’s normal functioning; it is a debilitating condition same as any other that stops us from leading a full life.  Studies revealed that the lifetime prevalence of MDD is around 20% that equates to over a billion people worldwide.  

The World Health Organization reported that MDD is quickly becoming one of the leading cause of disability among modern man.  The United States alone spends an estimated $65 billion a year for the direct treatment costs, lost of work productivity and suicide morbidity all contributed to Major Depressive Disorder. 


Through the understanding of the missing link between stress and depression, scientists are able to have a clearer picture of the cause and effect of MDD.  This has lead to more effective treatment plans and interventions which doesn’t only benefit the individual   but society as a whole.


If you notice that you or someone close to you continuously feels sad, unmotivated and has lost interest in usual activities it maybe the sign of depression and should be taken very seriously.  It is important to consult your physician or doctor immediately.  Learn more about depression here:  DEPRESSION 101