Damage to the hippocampus results in overactivity of the HPA axis, progressively higher levels of cortisol given off by the adrenal cortex, which leads to increasing destruction to the hippocampus. Chronic stress leads to overproduction of cortisol which has a damaging effect on the hippocampus. As more nerve cells in the hippocampus are lost, there is over-secretion of cortisol. There is speculation that this type of disregulation plays a role in the onset of Alzheimer's disease. There appears to be elevated basal cortisol levels in Alzheimer patients.
Alzheimer patients seem to show excess cortisol responses to stress.
Cortisol reduces hippocampal glucose metabolism in normal elderly, but not in Alzheimer's Disease. The excess exposure to cortisol is detrimental to memory performance, presumably due to its effect on the hippocampus. Perhaps some people who are susceptible to the brain disorder for other reasons may fall victim to it faster if their lives have been marred by excessive stress.