trauma effects (part 1 – the brain)

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Childhood abuse and other sources of extreme stress can have lasting effects on the parts of the brain that are involved in memory and emotion. The hippocampus, in particular, seems to be very sensitive to stress. Damage to the hippocampus from stress can not only cause problems in dealing with memories and other effects of past stressful experiences, it can also impair new learning. Recent research has shown that the hippocampus has the capacity to regenerate nerve cells (“neurons”) as part of its normal functioning, and that stress impairs that functioning by stopping or slowing down neuron regeneration.

In a study to try to see if PTSD symptoms matched up with a measurable loss of neurons in the hippocampus, Vietnam combat veterans with declaratory memory problems caused by PTSD, were tested, using brain imaging, these combat veterans were found to have an 8% reduction in right hippocampal volume (i.e., the size of the hippocampus), measured with magnetic resonance imaging (MRI), while no differences were found in other areas of the brain. This diminished right hippocampal volume in the PTSD patients is associated with short-term memory loss. Similar results were found when PTSD sufferers who were victims of childhood physical or sexual abuse were tested.

Further study on the question of memory and the hippocampus may some day shed light on the controversy surrounding delayed recall (or “recovered memories”) of childhood abuse. The hippocampus plays an important role in connecting and organizing different aspects of a memory and is thought to be responsible for locating the memory of an event in its proper time, place and context.

It’s suspected that damage to the hippocampus following exposure to the stress brought on by childhood abuse leads to distortion and fragmentation of memories. For instance, in the case of the PTSD sufferer who was locked in a closet as a child, she had a memory of the smell of old clothes but other parts of her memory of the experience, such as a visual memory of being in the closet or a memory of the feeling of fear, are difficult to retrieve or completely lost. In cases like this, psychotherapy or an event that triggers similar emotions may help the patient restore associations and bring all aspects of the memory together.

Besides the hippocampus, abnormalities of other brain areas, including medial prefrontal cortex, are also associated with PTSD.

The medial prefrontal cortex regulates emotional and fear responses. The medial prefrontal cortex is closely linked to the hippocampus. In several studies have shown dysfunction of both the medial prefrontal cortex and the hippocampus at times when patients were suffering from PTSD symptoms.
This dysfunction in these medial prefrontal regions may underlie pathological emotional responses in patients with PTSD. For example, sometimes a failure of extinction of fear responsescan be seen — a rape victim who was raped in a dark alley will have fear reactions to dark places for years after the original event, even though there is no threat associated with a particular dark place. In a study using combat-related slides and sounds to provoke PTSD symptoms, combat veterans with PTSD had decreased blood flow in the area of the medial prefrontal cortex. Significantly, this did not occur in combat veterans without PTSD.

PTSD – the invisible epidemic (part 1, the brain)

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Post-traumatic Stress Disorder (PTSD) is something of an invisible epidemic. The events underlying it are often mysterious and always unpleasant. It is certainly far more widespread than most people realize. For example, a prime cause of PTSD is childhood sexual abuse. About 16% of American women (about 40 million) are sexually abused (including rape, attempted rape, or other form of molestation) before they reach their 18th birthday

Childhood abuse may be the most common cause of PTSD in women, 10% of whom suffer from PTSD (compared to 5% for men) at some time in their lives, but many other types of psychological trauma can cause the disorder — car accidents, military combat, rape and assault.

Recent studies have shown that victims of childhood abuse and combat veterans actually experience physical changes to the hippocampus, a part of the brain involved in learning and memory, as well as in the handling of stress. The hippocampus also works closely with the medial prefrontal cortex, an area of the brain that regulates our emotional response to fear and stress. PTSD sufferers often have impairments in one or both of these brain regions. Studies of children have found that these impairments can lead to problems with learning and academic achievement.

Other typical symptoms of PTSD in children, including fragmentation of memory, intrusive memories, flashbacks, dissociation (or the unconscious separation of some mental processes from the others, e.g., a mismatch between facial expression and thought or mood), and pathological (“sick”) emotions, may also be related to impairment of the hippocampus. Damage to the hippocampus, which processes memory, may explain why victims of childhood abuse often seem to have incomplete or delayed recall of their abusive experiences.