Research has long indicated that individuals with depression often exhibit abnormal levels of cortisol, a key stress hormone released by the neuroendocrine system during the body's fight-or-flight response. Elevated cortisol is particularly prevalent in depressed individuals who have experienced early life trauma, such as childhood abuse or the loss of a parent.

HPA Axis Dysfunction and Cortisol Levels in Depression

- Levels of adrenal glucocorticoids are abnormally high
- Makes you more prone to depression
- Causes include hormone-secreting tumors, or treatment with synthetic glucocorticoids
- Depression occurs early in those with this syndrome
- Other typical signs include obesity and unusual growth and distribution of body hair
- These sign suggest that dysfunction of the hypothalamic-pituitary-adrenal axis may be involved in depression

Michigan State University

- Increased blood flow in the pre-frontal cortex and amygdala
- Decreased blood flow in the parietal and posterior temporal cortex
- Descendants of people with severe depression are shown to have a thinner cortex across the right hemisphere, possibly making them more vulnerable to depression
- Reduced volume in the hippocampus of depressed people
- However, it is unclear whether these changes in the brain were present before the depression

Changes in the brain associated with Depression

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Cushing's Syndrome

Depression is associated with dysfunctional activity in key brain areas responsible for processing and regulating emotions. Specifically, these include the amygdala, which is central to evaluating the emotional importance of events, and the prefrontal cortex (PFC), which plays a crucial role in controlling emotional responses.

Brain Abnormalities in Depression: Amygdala and Prefrontal Cortex

A neuroimaging study compares the brains of 50 individuals diagnosed with a major mood disorder characterized by persistent sadness to 50 non-diagnosed individuals. The study finds that, on average, the diagnosed group has a significantly smaller hippocampus. The lead researcher concludes in a press release, 'Our research proves that a shrinking hippocampus is a direct cause of this disorder.' Based on the current understanding of the relationship between brain structure and this condition, critically evaluate the researcher's conclusion. Is the conclusion fully supported by the evidence presented? Explain your reasoning.

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