Hypotheses and controversies related to effects of stress on the hippocampus: An argument for stress-induced damage to the hippocampus in patients with posttraumatic stress disorder

✍ Scribed by J. Douglas Bremner

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 251 KB
• Volume: 11
• Category: Article
• ISSN: 1050-9631
• DOI: 10.1002/hipo.1023

✦ Synopsis

In 1990 my colleagues and I saw Robert Sapolsky from Stanford University present data at the Society for Neuroscience Annual Meeting, showing that extreme stress was associated with structural changes in the hippocampus, a brain area that plays an important role in learning and memory. At that time we had started an inpatient program for the research and treatment of posttraumatic stress disorder (PTSD), a psychiatric disorder which sometimes follows exposure to extreme stress. This program was comprised of patients with PTSD related to exposure to the severe stress of combat in Vietnam. At that time there was very little research in the area of the neurobiology of PTSD. We were interested in changes in memory that we saw in our patients with PTSD. For instance many patients with PTSD had trouble remembering their appointments with their doctors. At that time as a young psychiatry doctor in training, I was under the supervision of psychiatrists trained in the tradition of psychoanalysis, who told me that if patients forgot their appointments that should be interpreted as resistance to treatment. However, I was curious about whether there might be other explanations to account for their behavior. For example, I noticed that although patients had trouble remembering what they had for breakfast that morning, when showing me pictures from their scrapbooks of Vietnam they could remember their comrades from combat and things that happened to them during that time 30 years ago as if it had happened yesterday.

During that period of my training, a combat veteran called me in the middle the night in the middle of a flashback. He kept saying over and over, "Got to get them out, got to get them out," for 20 minutes before he was able to slow down and have a regular conversation with me. While he was in the flashback he was not aware of what I was saying and was lost in his own world. It turned out that he had been a fireman in Vietnam and had to go into burning helicopters and pull soldiers out. Sometimes he was able to save people but at other times he was unable to get people out in time, and all that he pulled out were charred bodies. That night he had rushed into a burning house and pulled out two small children. He had in fact been a hero; however, this event triggered a flashback that took him back to Vietnam. Flashbacks are a symptom of PTSD that represent a playing out of a traumatic event in a dissociated state. Patients often describe them as if a movie is playing in front of their eyes, complete with visual image, sounds, and smells. When patients are having flashbacks, as my veteran had been, they are unaware of what is going on in the here and now. When I experienced my first patient having a flashback I was impressed at the automatic and uncontrollable nature of the symptoms, which were similar to those of patients I had seen who were having seizures. I wondered if, like seizures, they represented a neurological rather than a psychological condition, as they were considered to be at that time. If so, flashbacks should involve the same brain areas that are most affected by seizures, specifically the hippocampus (which is affected in 80% of patients with epilepsy). It was at this time that we became aware of research by Robert Sapolsky, Bruce McEwen, and others showing that stress has a detrimental effect on the hippocampus in animals. These data, together with studies of electrical stimulation of the hippocampus which resulted in dissociative states, fear reactions, and other symptoms seen in PTSD, made the hippocampus an area of high interest for research in PTSD.