New Research Identifies Post Traumatic Stress Gene

Why is it that when a group of soldiers share a horrific battle
experience, some are able to work through it and get on with their
lives while others suffer the persistent anxiety, emotional numbness
and bomb-blasted nightmares of post-traumatic stress disorder (PTSD)?
The answer, researchers have long believed, is that an individual's
response to trauma — whether in battle, or as result of a natural
disaster, a violent crime or some other horror — depends not only on
the intensity of that trauma but also on a complex interplay of past
experiences and genetic factors. A new paper, published in the current
issue of the Journal of the American Medical Association, provides remarkable support for this explanation and identifies a specific gene that influences susceptibility to PTSD.

The study, led by a team at Emory University, looked at 900 adults —
most of them low-income and African-American — seeking medical care at
two clinics in Atlanta. A history of trauma is common in poor, urban
populations, and the researchers found that 80% of the subjects had
been exposed to trauma, with the great majority exposed to multiple
traumatic stressors in their lives. "Over a third said they had a
friend or family member murdered," says Dr. Rebekah Bradley, assistant
professor of psychiatry and behavioral science at Emory. About 30% had
been abused as children — a well-established risk factor for developing
PTSD.

March 18, 2008 -- Cutting-edge new research helps answer the puzzling question of why post-traumatic stress doesn't happen to everyone who endures horrible trauma.

In this case, the trauma was child abuse. The researchers found that survivors of child abuse were particularly likely to have symptoms of post-traumatic stress as adults if they also had specific variations in a stress-related gene.

Among adult survivors of severe child abuse, those with the specific gene variations scored more than twice as high (31) on a scale of post-traumatic stress, compared with those without the variations (13).

The worse the abuse, the stronger the risk in people with those gene variations.

The study of 900 adults is among the first to show that genes can be influenced by outside, nongenetic factors to trigger signs of post-traumatic stress disorder, or PTSD.

"The study is groundbreaking," the largest of just two reports to show molecular evidence of a gene-environment influence on PTSD, said Karestan Koenen, a Harvard psychologist doing similar research. She wasn't involved in the new study.

"We have known for over a decade, from twin studies, that genetic factors play a role in vulnerability to developing PTSD, but have had little success in identifying specific genetic variants that increase risk of the disorder," Koenen said.

The results suggest that there are critical periods in childhood when the brain is vulnerable "to outside influences that can shape the developing stress-response system," said Emory University researcher and study co-author Dr. Kerry Ressler.

The study appears in Wednesday's Journal of the American Medical Association.

 Genetic Variations May Influence Depression in Those Who Suffered Child Abuse (Interview with Dr. Kerry Ressler, MD, PhD)

(February 4, 2008 - Insidermedicine) Genetic makeup interacts with childhood trauma to help determine the risk for developing depression in adulthood, according to a study published in the Archives of General Psychiatry.



Here is some information about depression and genetics:



•    Several studies looking at the risk of depression among family members and twins have suggested that there is a genetic component to the risk of developing depression.



•    It is important to remember, however, that having a genetic susceptibility to depression does not mean you will develop it. Several elements, including environmental, social, behavioral, and cultural factors interact to influence whether a person will become depressed.



•    Identifying individuals who are at high risk for depression based on their genetic makeup can help determine who needs help to prevent the disease, or at least treat it early on.



Researchers from Emory University in Atlanta looked for the presence of any of 15 small variations in a gene known as CRHR1 among over 600 adults, about two-thirds of whom had grown up disadvantaged. The CRHR1 gene was chosen because it affects a hormone believed to be involved in depression. The researchers also determined whether the participants had experienced abuse during childhood and depression during adulthood.



Individuals carrying certain variations of the CRHR1 gene were less likely to become depressed during adulthood after suffering abuse during childhood. This was true in both the disadvantaged and non-disadvantaged groups.



Today's research highlights how analyzing an individual's specific genetic makeup may, at some point in the future, help determine how much this person is at risk for developing depression, particularly following a traumatic period.