Depression is a neurological disorder. It can affect memory, concentration etc. There is altered activity of the brain in depression. Chronic depression in fact may lead to shrinking of the hippocampus which stores memories and helps in learning. Chronic Stress can lead to loss of growth of neurons and in fact their atrophy. That is why early and adequate treatment is as important mistreatment for a heart attack. The good thing is it is treatable and medication has few side effects, in fact no long term side effects are there