Originally Posted by sneakstooth

We all have a little stress in our lives. But after studying nerve cells in a banana-shaped area of the brain called the hippocampus, a hub for learning and memory, neuroscientists say chronic stress can have devastating effects on our brains.

“[Nerve cells] have these wonderful trees [with branches] that are called dendrites, places where other nerve cells make connections and transmit chemical signals,” says McEwen. These cells connect to each other at junctions called synapses.

“When we look at these individual nerve cells from an animal that’s stressed or not stressed, we could see some very characteristic changes. For example, the branches become shorter and less branched, as a result of repeated stress. That means there are fewer synaptic connections, and it means these cells are not receiving as much information as they normally do. When you look at many of these cells you realize that many of the cells in this brain area called the hippocampus show this shrinkage after repeated stress.”

McEwen’s team found the opposite was happening in the part of the brain that regulates fear and emotion, the amygdala . “With a chronic stress, neurons in the amygdala grow, they become larger,” says McEwen. “And there’s evidence that in depressive illness the amygdala may even become larger, and it certainly becomes more active.”

So, after exposure to chronic stress, if the cells in your hippocampus are shrinking, and the cells in your amygdala are growing, “you may have all sorts of anxieties and anger and fear, and yet you don’t have the hippocampus to help you connect it to where you were and what you were doing to make it specific. So you may have generalized anxieties as a result of this.”