How does depression physically affect the brain?

When we think about depression, what comes to mind are emotions, or, in some cases, the lack of emotions. But, to truly understand and therefore better treat depression, it is important to recognize the physical impact it can also have on the brain. 

Research up until today has acknowledged the role of chemical imbalances of neurotransmitters in the development of depression, but scientists in recent years have realized that it is much more physical and complex. 

>> Read more about the link between depression and brain dysfunction in our article here << 

Read on to learn more about how depression can affect the physical brain! 

Oxygen restriction 

A number of links have been found between depression and reduced levels of oxygen in the body. Scientists have hypothesized that this may be caused by changes in breathing during a depressive episode, but the order of occurrence and causes are still unclear. 

In individuals with major depressive disorder (MDD) and bipolar disorder, researchers have been able to observe elevated levels of a particular cellular factor produced in response to hypoxia (lack of oxygen) in the brain in their immune cells. 

The brain is very sensitive to hypoxia, which has been proven to lead to inflammation, as well as brain cell injury and brain cell death, which can further cause symptoms linked to development, mood, memory, and learning. 

The good news is that hyperbaric oxygen chamber treatment (often used to treat decompression sickness in scuba divers, certain infections, wounds that won’t heal due to diabetes, etc.), has been found to have a beneficial effect on depression symptoms in humans and may be a viable treatment option for some patients. 

Brain inflammation 

Researchers have begun to make links between inflammation and depression, though it is not yet clear whether the inflammation causes depression or vice versa. 

However, scientists have been able to determine that brain inflammation observed during depression is related to the length of time the person has been depressed. A study from researchers at the University of Toronto found that people who have been depressed for more than 10 years show 30% more brain inflammation than those who have been depressed for a shorter period. 

Due to the fact that inflammation in the brain can cause brain cell death, prolonged brain inflammation in people with major depressive disorder may experience a number of potential complications, including brain shrinkage, neurotransmitter dysfunction, and reduced neuroplasticity (ability of the brain to change as we age). These complications can further lead to issues with brain development, memory, mood and learning. 

Brain shrinkage 

Research conducted in 2018 observed shrinkage in specific areas of the brain in people who suffer from depression. More work is needed to identify the reasons behind and the magnitude of this shrinkage, but a number of studies in recent years have identified that the following brain areas can be affected: 

• The hippocampus, which plays a major role in learning and memory; 
• The thalamus, which relays sensory impulses from around the body to the cerebral cortex (responsible for interpretating touch, temperature, or pain); 
• The amygdala, the integrative center for emotions, emotional behavior, and motivation; 
• The frontal lobes, the brain region responsible for important cognitive skills such as emotional expression, problem solving, memory, decision-making, etc.; 
• The prefrontal cortices, part of the frontal lobe specifically implicated in complex behaviors (planning, personality development, etc.). 

Scientist have been able to link the duration and severity of this shrinkage to that of the depressive episode. 

When a part of the brain shrinks, so to the functions associated with that particular area. For example, the amygdala and the prefrontal cortex work in parallel to control recognition of emotional cues in others and our emotional response. When these areas experience shrink, it can contribute to a reduction in empathy, which can be seen in individuals experiencing postpartum depression (PPD). 

Structural and connective changes 

As mentioned earlier, depression can cause shrinkage to specific areas of the brain and therefore cause their dysfunction.  

For example, reduced functionality of the prefrontal cortex can affect their executive function and attention, dysfunction of the amygdala can affect emotional regulation and mood, and reduced hippocampal functionality can cause memory issues. 

These changes usually take a minimum of 8 months to develop and may persist for longer periods after longer-lasting depressive episodes, particularly affecting memory emotional regulation, mood, and attention. 

What can we do to prevent these physical brain changes? 

While this may sound scary or inevitable, here are a few helpful ways that can help prevent long-lasting changes to the brain. 

Ask for help: Therapy and stress management 

Though it is often not easy, one of the best ways to protect your brain is to ask for help.  

The more that we understand that depression is not just an “emotional problem,” but has significant neurochemical and physical impact on the brain, the more we can remove the stigma that keeps people from getting the mental help and support they need. It is important to remember that depression is not your fault and that you are not alone.

Both cognitive behavioral therapy (CBT) and group therapy incorporating stress management or mindfulness techniques can be useful tools to overcome stigma and find support. Plus, many studies have found that such techniques help to improve depression symptoms. 

Antidepressants 

Antidepressants can be an important tool in managing depressive episodes and the symptoms they may cause. These drugs balance the neurotransmitters in our brain, therefore helping to prevents the physical changes that can take place. 

It is important to speak with your doctor or mental health professional, as he or she can help you find the combination of therapy and/or antidepressant drugs that can help you better cope with your depression. 

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