One in nine women will have PTSD at some point in their life—twice the rate for men. Women are also more likely to experience extreme traumatic events, such as rape, that carry a high risk for the disorder.
“PTSD is not just a mental health issue,” says study senior author Karestan Koenen, PhD, Mailman School associate professor of epidemiology. “Along with cardiovascular disease and diabetes, we can now add obesity to the list of known health risks of PTSD.”
“The good news from the study is that it appears that when PTSD symptoms abate, the risk of becoming overweight or obese is also significantly reduced,” says first author Laura D. Kubzansky, PhD, professor of social and behavioral sciences at Harvard School of Public Health. However, despite the growing evidence of potential far-reaching problems associated with PTSD, it’s estimated that only half of women in the United States with the disorder are ever treated. “Hopefully, wider recognition that PTSD can also influence physical health will improve this statistic, leading to better screening and treatments, including those to prevent obesity,” says Dr. Kubzansky.
While it’s known that women with PTSD have high obesity rates, it has been unclear whether PTSD was actually driving the weight gain. To explore the question, the researchers analyzed data from 50,504 women, aged 22–44, who took part in the Nurses’ Health Study II between 1989 and 2009. Participants were asked about the worst trauma they had experienced and if they had related PTSD symptoms. The threshold for PTSD was the persistence of four or more symptoms over a month or longer. Common symptoms include re-experiencing the traumatic event, feeling under threat, social avoidance, and numbness.
Normal-weight women who developed PTSD during the study period had a 36 percent increased risk of becoming overweight or obese, compared with women who had experienced trauma but had no PTSD symptoms. The risk was increased even for women with sub-threshold symptom levels and remained after adjusting for depression, which has also been proposed as a major risk factor for obesity. In women with PTSD that began prior to the study period, body mass index (BMI) increased more rapidly than in women without PTSD.
The observed effect of PTSD on obesity is likely stronger in the general population of women than in nurses, says Dr. Koenen. “Nurses are great for studies because they report health measures like BMI with a high degree of accuracy. But they are also more health conscious and probably less likely to become obese than most of us, which makes these results more conservative than they would otherwise be.”
PTSD symptoms, rather than the trauma itself, seemed to be behind the weight gain. “We looked at the women who developed PTSD and compared them with women who experienced trauma but did not develop PTSD. On the whole, before their symptoms emerged, the rate of change in BMI was the same as in the women who never experienced trauma or experienced trauma but never developed symptoms,” says Dr. Kubzansky.
How exactly does PTSD lead to weight gain? The biological pathway is unknown, but scientists have a number of guesses. One is through the over-activation of stress hormones. PTSD may lead to disturbances in functioning of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, each of which is involved in regulating a broad range of body processes, including metabolism. Another is through unhealthy behavior patterns that may be used to cope with stress. Ongoing research is looking at whether PTSD increases women’s preference for processed foods and decreases the likelihood of their exercising.
Co-authors are Pula Bordelois, MPH, and Andrea Roberts, PhD, at Harvard School of Public Health; Hee Jin Jun, DrPH, at the Channing Division of Network Medicine at Brigham and Women’s Hospital; Noah Blustone, BA, at Harvard Medical School and Boston University; and Magdalena Cerda, DrPH, at Columbia’s Mailman School.
The study was supported by grants from the National Institute of Mental Health to Dr. Koenen (MH078928 and MH093612). The authors declare no conflict of interest.
This article originally appeared on the Mailman School of Public Health website.