Health
Recent combat veterans who are diagnosed with post traumatic stress disorder have significantly smaller volume in an area of the brain critical for regulating fear and anxiety responses, according to research led by scientists at Duke University and the Durham VA Medical Center.
The finding, published Nov. 5, in the journal Archives of General Psychiatry, for the first time provides clear evidence that smaller amygdala volume is associated with PTSD, regardless of the severity of trauma.
But it’s not clear whether the physiological difference was caused by a traumatic event, or whether PTSD develops more readily in people who naturally have smaller amygdalas.
“Researchers found 20 years ago that there were changes in volume of the hippocampus associated with PTSD, but the amygdala is more relevant to the disorder,” said Rajendra A. Morey, M.D., M.S., assistant professor at Duke and lead author of the study. Morey said studies in animals have established the amygdala’s role in regulating fear, anxiety and stress responses, but its effect on human behavior is less well known.
“It’s associated with how fear is processed, especially abnormal fear processing.” Morey said. “So it makes sense to look at the structure of the amygdala.”
The researchers enrolled 200 combat veterans who served in Iraq and Afghanistan after Sept. 11, 2001; half had PTSD and the other half had been exposed to trauma, but had not developed PTSD. Amygdala and hippocampus volumes were computed from MRI scans of all the participants.
The researchers found significant evidence that PTSD among study participants was associated with smaller volume in both the left and right amygdala, and confirmed previous studies linking the disorder to a smaller left hippocampus.
The differences in brain volumes between the two groups were not due to the extent of depression, substance abuse, trauma load or PTSD severity – factors the researchers took into account in their statistical model.
The finding provides new insight into a condition that strikes nearly 14 percent of combat veterans serving in Iraq and Afghanistan, according to the Department of Veterans Affairs.
PTSD also is estimated to afflict 6.8 percent of adults in the general population who have suffered abuse, crimes and other traumas over their lifetimes.
“The next step is to try to figure out whether a smaller amygdala is the consequence of a trauma, or a vulnerability that makes people get PTSD,” Morey said.
He said the study demonstrated that amygdala volume does not appear to be affected by the severity, frequency or duration of trauma, indicating that such exposures do not cause the amygdala to shrink.
As a result, it appears more likely that people with measurably smaller amygdala to begin with are susceptible to PTSD, but more studies are needed to make that determination.
Morey said he and colleagues are exploring that question, and are intrigued by evidence from their study that suggests people may have a propensity for developing PTSD based on inherently smaller amygdala volume.
“This is one piece in a bigger puzzle to understanding why some people develop PTSD and others do not,” Morey said. “We are getting closer to that answer.”
In addition to Morey, study authors include: Kevin S. LaBar; Shannon K. Beall; Vanessa M. Brown; Courtney C. Haswell; Jessica D. Nasser; H. Ryan Wagner.
All are associated with Duke and the VA’s Mental Illness Research Education and Clinical Center at the Durham VA Medical Center. Gregory McCarthy and Andrea L. Gold are from Yale University.
Funding for the study was from the U.S. Department of Veterans Affairs and the National Institutes of Health.
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Cardiac bypass surgery superior to non-surgical procedure for adults with diabetes and heart disease
Adults with diabetes and multi-vessel coronary heart disease who underwent cardiac bypass surgery had better overall heart-related outcomes than those who underwent an artery-opening procedure to improve blood flow to the heart muscle, according to the results from an international study.
The research was supported by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health.
The study compared the effectiveness of coronary artery bypass graft (CABG) surgery with a non-surgical procedure known as percutaneous coronary intervention (PCI) that included insertion of drug-eluting stents.
After five years, the CABG group had fewer adverse events and better survival rates than the PCI group.
Principal investigator Valentin Fuster, M.D., Ph.D., of Mount Sinai School of Medicine in New York City, will present the study findings on Sunday, Nov. 4, at 7:58 p.m. ET at the American Heart Association’s annual meeting in Los Angeles.
The findings will appear concurrently online in The New England Journal of Medicine. A companion paper on cost effectiveness will appear online in Circulation.
“These study results confirm that bypass surgery is a better overall treatment option for individuals with diabetes and multi-vessel coronary disease and may assist physicians’ efforts to prevent cardiovascular events such as heart attacks and deaths in this high-risk group,” explained Gary H. Gibbons, M.D., director of the NHLBI.
In coronary heart disease, plaque builds up inside coronary arteries. This often leads to blocked or reduced blood flow to the heart muscle and can result in chest pain, heart attack, heart failure, and/or erratic heartbeats (arrhythmia).
In 2010, nearly 380,000 Americans died from coronary heart disease. Approximately 25 percent to 30 percent of patients needing CABG or PCI have diabetes and multi-vessel coronary heart disease.
In the United States, more than one million procedures (CABG and PCI) are performed each year to restore circulation to patients with blocked arteries.
In CABG, surgeons try to improve blood flow to the heart muscle by using a healthy artery or vein from another part of the body to bypass a blocked coronary artery.
PCI is a less invasive procedure in which blocked arteries are opened from the inside with a balloon. A stent, or small mesh tube, is then usually inserted to prop the opened arteries so that blood continues to flow into the heart muscle.
The type of stent used in the study, called drug-eluting, is coated with medicine that is slowly and continuously released to prevent an opened artery from becoming blocked again.
The study, called Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multivessel Disease (FREEDOM), involved 140 international centers and a total of 1,900 adults enrolled from 2005 to 2010.
The participants had diabetes and coronary heart disease that involved narrowing of multiple blood vessels, but not the left main coronary artery, which usually requires immediate treatment with CABG.
At each clinical site, a team of specialists in neurology, heart disease, diabetes, and general medicine screened potential participants to ensure that they were eligible for both CABG and PCI.
Those who were selected for the trial were randomly assigned to receive one of the interventions. As recommended by international guidelines for patients who receive drug-eluting stents, the PCI group also received anti-clotting therapies.
A drug called abciximab was administered intravenously during the procedure, and clopidogrel was given orally for at least 12 months after the procedure, accompanied by aspirin for those who could tolerate it. Study participants were followed for at least two years.
During the trial, participants received standard medical care for all major cardiovascular risk factors such as high LDL cholesterol, high blood pressure, and high blood sugar. Participants also were counseled about lifestyle choices such as smoking cessation, diet, and regular exercise.
After five years, the CABG group had a lower combined rate of strokes, heart attacks, and deaths (18.7 percent) than the PCI group (26.6 percent).
Strokes, which are a well-known risk of bypass surgery, occurred slightly more often in the CABG group (5.2 percent) than in the PCI group (2.4 percent).
However, more people died from any cause in the PCI group (16.3 percent) than in the CABG group (10.9 percent). The survival advantage of CABG over PCI was consistent regardless of race, gender, number of blocked vessels, or disease severity.
“The advantages of CABG over PCI were striking in this trial and could change treatment recommendations for thousands of individuals with diabetes and heart disease,” said Fuster.
FREEDOM was supported by NIH grants HL071988 and HL092989. Cordis, Johnson & Johnson, and Boston Scientific provided stents. Eli Lilly provided an unrestricted research grant for abciximab, and Sanofi-Aventis and Bristol Myers Squibb donated clopidogrel.
FREEDOM involved hundreds of investigators from more than 16 countries, with a clinical coordinating center at Mount Sinai School of Medicine and a data coordinating center at New England Research Institutes in Watertown, Mass.
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