Why Does a Major Depressive Disorder Change Your Brain?
Major depressive disorder (MDD) is characterized by persistent low mood, often accompanied by cognitive dysfunction, physical symptoms, and impaired social function. No one knows for sure what causes depression, but researchers have determined that it is definitely a disorder that has biological underpinnings, and that the chemistry of the brain plays a big role. According to National Institute of Mental Health data. In 2020, an estimated 14.8 million U.S. adults aged 18 or older had at least one major depressive episode with severe impairment in the past year. This number represented 6.0% of all U.S. adults.
The main subcortical limbic brain regions implicated in depression are the amygdala, hippocampus, and the dorsomedial thalamus. Both structural and functional abnormalities in these areas have been found in depression. Since this creates a feedback loop, issues with your amygdala can be one of the most dangerous things about major depressive disorder. The influx of cortisol triggered by depression also causes the amygdala to enlarge. This is a part of the brain associated with emotional responses. When it becomes larger and more active, it causes sleep disturbances, changes in activity levels, and changes in other hormones.
When you suffer from depression, your brain is physically changed. Research by the National Institutes of Health shows that you lose gray matter volume (GMV) when you suffer from depression. This loss is caused by parts of your brain shrinking due to the hormone cortisol impeding the growth of your brain cells. A depressed person’s brain goes through many changes due to the influx of brain chemicals and loss of matter. Brain is shrinkage, especially in the hippocampus, thalamus, frontal cortex, and prefrontal cortex. Major depression is linked to cerebral inflammation.
Depression alters both your mind and body, and almost always for the worse. The hormones released during episodes of depression can cause cerebral damage, emotional instability, sleep disorders, and impaired cognitive abilities. The most effective treatment for depression is a combination of therapy and medications, both of which take time to work.
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Larson, D. (2022, November). Nervous System [PowerPoint slides 55-80]