Hi Matt,

To answer your first question --again there is evidence shows shrinkage --but once proper medication and treatments are done the damge stops some cases possiby reversed .

To your 2nd question yes as well --but only if left untreated why because the affect on genes and the hormones levels like cortisol.

In depression, the body’s stress-response systems are going nonstop. Hormones (like cortisol) stream through the body The effects of this long-term stress response are devastating for the brain and the body. The body responds by increasing adrenaline, by elevations in blood pressure, by increased blood levels of sugars and fats.

The brain responds by having its alarm systems in an always-on. The amygdala, the brain’s panic system, actually grows in size! The hippocampus, the brain’s center of working memory, and the prefrontal cortex, the area of planning and memory do shrink. Chronic depression is very toxic for your brain.

DD is also toxic for your body. People who are chronically depressed are at greater risk of heart disease, diabetes, osteoporosis, and many other medical problems. Nobody knows exactly why this atrophy occurs. Neurons may die or shrink, or ones that should have been born to replenish the region may not be. Whichever, it does seem linked to a stress hormone called cortisol, because about half of seriously depressed patients secrete too much cortisol.

After meication and reduction in cortisol levels saw their brain chemical return to normal, cell growth and restart and the hippocampus return to its pre-depression size.

This in hippocampal volume loss in depressed humans could possibly be prevented by anti- depressants.