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Understanding Depression: When Feeling Sad Is A Sign Of Mental Illness

by — 2014-10-03 in Mental Health
Sometimes we feel sad and it is normal. But if this interferes with our daily life, we may be suffering from depression. Being it a major health concern in the world, it´s important that we treat depression as a mental problem and understand its causes.

Understanding how the brain works has never been easy for scientists. This organ is one of the most complex ones in our body and its normal function can be easily altered by a wide number of diseases. One of these illnesses is depression. Yes, depression is a disease that is very common worldwide but is still poorly understood.

Depression is more serious than you think 

For years, research has focused in elucidating the causes of depression in order to develop more effective treatments for this mental disease.

According to the World Health Organization (WHO), more than 350 million people of all ages suffer from depression.

But is this just a transient state of mind related to mood changes or is it something more serious? Many people will argue that depression is not an illness and as such, people suffering from it should be able to cope and come out from their state easily. Well, they could not be more wrong. 

Depression is a mental disorder, which is more common in women, that shows a wide spectrum of symptoms and severity.  In some cases, it could be easily treated; in others, it could even lead to suicide.

Symptoms of depression are basically feelings of sadness and hopelessness that can last for days, weeks or even months.

People with depression loose interest in activities that they used to enjoy and isolate themselves from friends and family.

Apart from the psychological and social symptoms, depressed people also feel tired, they may show a reduction in weight due to lack of appetite, but it can also be all the way around. Constipation, aches, pains and sleep disorders are also signs of depression.

What happens inside the brain of a depressed person?

In a normal brain, the signals travel from neuron to neuron in the form of chemical substances. These substances are released by the neuron that sends the message. When released, they activate a very well designed machinery in the recipient neuron; in turn, this neuron processes the message and converts it into an electrical signal, which travels along the neuron until it reaches its end, known as axon terminal, activating again the release of chemical substances. In this way, a message travels from one neuron to another.

The chemical substances we refer to here are called neurotransmitters and each one of them activates and inhibits the response of specific neurons in specific regions of the brain in order for this organ to be able to handle information related to all sorts of physiological functions, from muscle movement to memory.

Serotonin is one of the neurotransmitters that participate in the processing of information in our brain.

Serotonin is a very well known neurotransmitter because it is related to feelings of happiness, but it also regulates other physiological activities such as sleep, appetite and the inhibition of pain.

See Also: What depression does to a person?

With this in mind, researchers thought that depression was a consequence of a dysregulation in neurotransmitter levels in the brain, specifically of serotonin. They came up with this theory based on the evidence that they had that indicated that levels of depression in patients were reduced with medicines that promoted the release of serotonin. 

This was the common believe for ages, however, in recent studies, it has been shown that this is just the tip of the iceberg and that depression is not only explained by a lack of serotonin in the brain.

Depression Is All About Neuronal Connections  

What is happening then? Even though low serotonin levels do play a role in the development of depression, researchers have shown that it is also caused by alteration in the neuronal connections in certain brain structures that control our emotions.

The limbic system 

The limbic system is composed by the amygdala and the hippocampus, among other structures that play a role in the control of a variety of cognitive functions.

The amygdala for example, is in charge of managing emotions such as sexual arousal and pleasure, anger, sorrow and fear. The hippocampus, on the other hand, is the brain region that specializes on the learning and memory processes.

Together with the amygdala, the hippocampus keeps memories associated to emotions. Remember the first time you touched something hot? The pain you felt because of this action was from then on stored in your brain and linked to that specific situation. Now you know that you should not touch hot surfaces with your bare hands, because it can harm you. This is how team hippocampus/amygdala work.

Research has shown that depressed persons suffer alterations in their amygdala and hippocampus.

Depressed patients show a more active amygdala and several studies have identified that the size of their hippocampus also changes.

In a recent study published in the Journal of Psychiatry Research, a reduction in the volume of the hippocampus of patients that suffered from major depressive disorder was detected. Scientists believe that stress could be playing a major role in the alteration of hippocampal morphology and size.

Neurogenesis and genes 

So basically, not only the imbalance in the level of neurotransmitters alters the mood of a person.

A reduction in the number of neurons and therefore in the size of the brain regions involved in mood control affect the neuronal connections that deal with emotions and feelings, basically altering the wiring in our brain and driving people into a deep state of sadness.

This theory is supported by the fact that antidepressants not only affect the level of neurotransmitters, they also promote the growth of new neurons, known as neurogenesis, and the development of new neuronal connections. This property of antidepressants was only recently discovered and it might explain their effectiveness in the treatment of depression.

Genes are also involved in the development of depression.

Researchers have focused in identifying mutations in certain genes related to the production of serotonin, for example, to see if this mutations increase the risk of depression.

See Also: Treating Depression - What Are Your Options?

It is not easy however to blame just one gene for this disorder, since it is a very variable disease. Nevertheless, it is known that a person with a relative facing depression has an increase in the risk of suffering it as well of almost 3%, compared to the normal.

Depression is a major health concern all around the world. If you think you suffer from this mental illness or you know someone that might, do not hesitate to look for help. This is a completely treatable disease but it has to be correctly diagnosed and followed by a specialist. 

Sources & Links

  • COBB, J. A., SIMPSON, J., MAHAJAN, G. J., OVERHOLSER, J. C., JURJUS, G. J., DIETER, L., HERBST, N., MAY, W., RAJKOWSKA, G. & STOCKMEIER, C. A. 2013. Hippocampal volume and total cell numbers in major depressive disorder. J Psychiatr Res, 47, 299-306.
  • Mindmap by steadyhealth.com
  • Photo courtesy of geralt by Pixabay : pixabay.com/en/man-face-confused-head-depression-416473/

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