"Major depression is profound depression. The person with major depression usually experiences a complete loss of pleasure in nearly everything that once brought them happiness. These episodes usually are not triggered by any specific event. During a depressive episode, even a positive event does not lift the person’s mood much. Major depression often interferes with a person’s ability to work or go to school, sleep, study, or eat. At least half of the people who suffer from one depressive episode will experience a second within 10 years. But other types of depression have been also identified, including dysthymia, postpartum depression, bipolar disorder (formerly called “manic depression”) and seasonal affective disorder (SAD)."
The show outlines research that suggests, through brain imaging, that people with depression show changes in the region of the brain known as the hippocampus. In other words, depression is associated with a physical change in the brain. This seems to have to do with the fact that nerve cells in the hippocampus are responsive to stress hormones, such as cortisol. Stress motivates us to both physical or mental activity;, but if we are not able to burn off the extra fuel our bodies produce in response to stress hormones, it can overload our systems and affect bone density, blood pressure, and other systems. Too much stress over too long a period of time (in the form of the stress hormones cortisol and adrenaline) may disregulate this part of the neurological system.
The hippocampus is a structure in the brain shared by all mammals. Because of its shape, it was given a name derived from "seahorse." It is thought to play an important role in certain types of memory and of spatial recognition. Damage or lesions to parts of the hippocampus can be seen in people suffering from Alzheimers, forms of amnesia, and other conditiions. Shrinkage, or atrophy of the hippocampus ("reduced hippocampal volume" the studies call it) has been observed in people suffering from schizophrenia, bipolar disorder, major depressive disorder (MDD), and post-traumatic stress disorder. Although there are many unanswered questions about the implications of these recent findings, one striking implication that is being studied is that early diagnosis and treatment can not only help people manage their symptoms, but also actually help heal the part of the brain that seems to suffer the effects or cause (it's not clear which) these disabling conditions.
What is more, brain scans have also shown that anti-depressants, the medications used to treat depression, can not only alleviate symptoms, but also affect (halt or reverse) damage to the hippocamus. Studies also show increased hippocampal volume in London Taxi Drivers, who must remember every single street in London and pass a test called "The Knowledge". Part of the hippocampus was larger than average in these drivers, especially those who had been driving longer! The hippocampus helps lay down a spatial map, and has a role in the "recollection function" of memory.
Neuroplasticity! gotta love it.
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