Feeling depressed or sad are normal reactions to life's challenges. But when sadness or feelings of hopelessness and defeat last for days or weeks, they can have a significant impact on your life.
A persistent feeling of sadness may be a sign that you have clinical depression, a treatable medical condition.
Depression, sometimes referred to as major depressive disorder, is one of the most prevalent mental health disorders in the United States. The condition affects more than 19 million adults¹, or about 8% of the population annually.
For some people, major depression causes overwhelming feelings of sadness and despair that severely interfere with their ability to lead a normal, active life.
In addition to affecting a person psychologically, clinical depression can cause various physical symptoms. For example, major depression can lead to pain, headaches, digestive issues and has the potential to alter your brain's physical structure.
While depression can be triggered or caused by several factors, researchers have long suspected the disorder was related to chemistry in the brain.
Recent studies have found that not only does the brain's structure and chemicals play a role in depression, but that the disorder can also cause physical changes to the brain². These changes may include inflammation, oxygen restriction, structural and connectivity changes, and brain shrinkage.
Inflammation³ is the immune system's normal response to infection and disease. The human body typically uses inflammation to protect and heal itself after injury or trauma. However, too much inflammation is potentially damaging.
Researchers have discovered that there is a link between depression and inflammation of the brain⁴. While the connection between depression and brain inflammation is still unclear, a 2015 study found inflammation deep in the brains of patients who have this mental disorder.
In addition, the study found that the severity of the inflammation is related to the time a person has been depressed. For instance, research showed that brain inflammation increased by an average of 30% in individuals who suffered from clinical depression for over ten years².
Unlike an inflamed ankle or wrist, brain inflammation isn't painful. Instead, one of the most common symptoms is brain fog, where thoughts are slow, fuzzy, or unclear. Other symptoms of brain inflammation⁵ include anxiety, irritability, anger, memory loss, and fatigue.
But brain inflammation doesn't only affect your performance and ability to think clearly. Studies have also discovered that the immune cells that trigger inflammation can misguidedly attack and damage healthy cells. In the case of brain inflammation, this can cause the brain cells to die⁶, leading to a number of complications.
Clinical depression has also been linked to hypoxia, or oxygen restriction, in the brain. The normal functioning of the brain is highly dependent on an adequate supply of oxygen from the blood.
Brain hypoxia⁷ can also be worsened by the inflammation associated with depression and causes symptoms such as:
Temporary memory loss
Reduced ability to move your body
Difficulty paying attention
Difficulty making sound decisions.
Major depression can also cause structural and connective changes² in the brain. Multiple structural and functional connections in the brain enable the interaction of different regions which control various physical and mental functions.
Clinical depression has been shown to reduce the functionality of three critical regions of the brain, including:
The hippocampus. Reduced functionality of the hippocampus can lead to memory impairment.
The prefrontal cortex. The prefrontal cortex is critical to self-regulation skills and the mental processes used to plan, focus, remember instructions, and multi-task. Reduced functionality in this region can severely decrease an individual's ability to get things done.
The amygdala. The amygdala is integral to controlling emotions, emotional behavior, and motivation. A reduction in functionality of the amygdala can directly impact the regulation of moods and emotional responses.
A study performed by Yale University⁸ researchers found that major depression can cause a loss of brain volume, contributing to cognitive and emotional impairment.
While there is still debate about which brain areas are affected and the extent of damage, evidence shows that depression causes shrinkage of the hippocampus, thalamus, amygdala, frontal, and prefrontal cortices.
Major depression that lasts for an extended period not only causes feelings of overwhelming sadness and despair but also results in structural and neurochemical changes in the brain.
This damage to the brain can cause patients to have difficulties with memory and concentration.
While these symptoms persist in a small percentage of people after their depression improves, these changes to the brain are not permanent⁹ for most people.
Evidence shows that the structural damage to the brain caused by major depression can be blocked and even reversed with antidepressant treatments.
Major depression is a common mental disorder that significantly affects a person's ability to live a healthy, productive life. While living with depression can be overwhelming, there is help available.
If you have been dealing with intense feelings of sadness that persist, it's vital to seek medical attention. The first step to getting help for your depression is to talk to a professional about your situation.
If you think you may be suffering from depression, schedule a visit with your primary care physician or a community mental health center and ask them to refer you to a mental health specialist.
You can also contact the Substance Abuse and Mental Health Services Administration's free National Helpline¹⁰, available 24 hours a day, 365 days a year, for information and treatment referrals.
There are many effective treatments available that can improve your depression symptoms and enable you to take back control of your life.
Major depression is a serious mental health disorder that can have life-altering effects. The condition can cause a wide range of psychological and physical symptoms and lead to other severe medical conditions.
In addition to the mental and physical symptoms, chronic depression alters the physical structure and chemistry of the brain.
Fortunately, with proper treatment, depression symptoms can be controlled, and the damage to the brain reversed.
Major Depression | National Insitute of Mental Health
National Helpline | Substance Abuse and Mental Health Services Administration
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