A new study confirms that there is a link between post-traumatic stress disorder (PTSD) in women and an increased rate of obesity, and other research indicates that health issues such as these may be multigenerational.
In research conducted using data collected in the Nurse’s Health Study II, it was determined that PTSD had an effect on obesity rates that was outside of the effects of depression and that women with PTSD were up to 36 percent more likely to be overweight or obese. The first longitudinal study to be conducted on the subject, the study involved looking at data collected that ranged from 1989 to 2005 and included the PTSD symptoms and BMI measurements for 54,224 participants, age 22-44, in the Nurse’s Health Study II.
Researchers used the Trauma and PTSD Screening Questionnaire to determine factors such as trauma, the beginning of symptoms and what kind of symptoms were presenting themselves. The BMIs of the participants were then examined, using a BMI of 25.0 as a threshold for the overweight category and 30.0 as a threshold for obese. The data was then analyzed to control for the influence of depression, as depression also has been shown to have a significant impact on obesity rates.
Following analysis, researchers discovered that women who had BMIs in the normal range in 1989, but had also experienced at least 4 symptoms of PTSD at that time demonstrated more weight gain than women in the study who had not experienced PTSD symptoms. This effect was consistent, even in women who experienced symptoms on the more mild end of the spectrum. Women whose PTSD did not develop until after 1989 showed BMI increases consistent with the women who had no symptoms until the onset of their own, when their BMIs increased at a faster rate.
Researchers believe that the causes of these increases in weight gain are both biological and behavioral in nature. They suggest that these results should be used to inform treatment of PTSD so that it includes health conscious behavioral modification. Currently, treatment for PTSD largely overlooks this element.
The results of this study provide an insight into how the risk of obesity in women is increased by PTSD, but other recent research has yielded a new approach to heritability that shows that these types of health concerns may be multigenerational.
In another recent study, researchers used mice to demonstrate how the effects of traumatic experiences appear to be passed down to offspring. Three groups of mice were used. One group served as a control, with no intervention enacted upon them. Another group was introduced to the smell of acetophenone. This group was then conditioned to fear the smell through the introduction of an electric shock that accompanied the smell and would eventually shake with fear at the smell without experiencing the shock. A third group was conditioned in the same way, but with a different odor.
Then, the mice were bred using natural and in vitro fertilization. What was discovered was that the next two generations of mice whose parents had been conditioned to fear acetophenone continued to have an elevated level of responsivity to the smell. This response was not present in the mice whose parents had received no conditioning, nor was it present in the mice whose parents were conditioned to a different smell and then exposed to acetophenone.
This research is not without controversy, however, as it is commonly accepted that most changes in genetics occur over several generations as the result of random mutations of the genes themselves.
One possible explanation for how this type of inheritance can occur is through modifications of genes on an epigenetic level. What this means is that the environment impacts the parent to the point that it influences how different genes are expressed rather than changing the genes themselves. However, since specific mechanisms behind these types of changes have yet to be isolated, nothing conclusive can be determined.
The potential implications of this study demonstrate that issues stemming from trauma can be passed down to children, whom can then have these issues without having experienced the trauma. This could mean that complications from trauma, such as elevated rates of obesity, could also spread to subsequent generations.
There is another study that has found that epigenetic factors were at play with increased rates of obesity in descendents of those exposed to DDT in the early to mid 1900s. Research on this topic revealed that the effects of epigenetic transference was present in the great-grandchildren of rats exposed to DDT and that 50 percent of the great-grandchildren developed obesity in their lifetimes.
The implications of this research, should it hold up to peer scrutiny and further investigative efforts, is that both obesity and trauma have the potential to be transgenerational in nature. Women suffering with PTSD may see not only their own risk of obesity increased but a multigenerational legacy of trauma and obesity risk factors.
By Vanessa Blanchard