A new study by 23andMe found that low-income women are more than two times as likely to have self-reported that they had post-traumatic stress disorder (PTSD) than men of any income, and the study confirmed strong links to other mental health conditions such as anxiety and depression.
The unpublished study is among the largest studies ever done on PTSD, and included a diverse cohort not limited to veterans or other groups that had in the past been the focus of PTSD research. It included data from about 3 million 23andMe customers who consented to participate in research, 400,000 of whom self-reported being diagnosed with or treated for PTSD. While previous studies have shown that women are more likely to be diagnosed with PTSD, this finding indicates that the difference is even more profound for low-income women, even when compared to other women of higher socioeconomic status.
A Snapshot of the Effects of Trauma
Trauma is a part of life for many of us. According to a World Mental Health Survey, 70 percent of people will experience some sort of traumatic event. But only a small percentage of those who experience trauma develop the long-term intense, emotional, and physical symptoms that characterize PTSD.
In the United States, about six percent of the population will experience PTSD at some point in their lives, according to data from the Veterans Administration. This aligns with 23andMe’s data, which also found that about six percent of the participants in this study had self-reported a diagnosis for PTSD or reported that they’d been treated for PTSD.
Henri Garrison-Desany, a former 23andMe intern, led the work for this internal study during his time at 23andMe. Henri is now a postdoc at Harvard University’s T.H. Chan School of Public Health.
Henri noted that PTSD offers a vivid example of the interplay between environment (a traumatic event) and genetic factors that come together to impact mental health. In other words, a person may be more genetically predisposed to experience PTSD, but it’s the trauma that triggers the condition. While our study was limited in that it did not allow for follow-up, for instance, it offers an important snapshot of individuals who report experiencing PTSD.
“Data from 23andMe shows the importance of large cohorts as well,” Henri said. “Because [PTSD] is a relatively rare diagnosis compared to depression or anxiety, having a large database helps to determine enough cases to run analyses.”
Unlike some other studies, the individuals included in our study self-reported their diagnosis or treatment for PTSD. In addition, this study does not characterize the type of trauma or the timing of that trauma. But the wide lens approach allowed our researchers to ensure our study would include individuals who may not be included in other studies.
The work also adds important data to 23andMe’s broader research into depression and bipolar disorder and other mental health conditions.
What is PTSD?
While commonly associated with experience in combat, post-traumatic stress disorder can develop after any trauma, such as from a sexual or physical assault. Even a violent traffic accident can lead to PTSD.
PTSD is a mental health condition characterized by such things as mood changes, anxiety, or sleep disruption. Some of those with the condition experience physical symptoms such as a racing heart rate. It can last for extended periods of time. Those with the condition might feel as if they are re-experiencing the original trauma through nightmares, flashbacks, or physical symptoms. People with PTSD might also make an extra effort to avoid places or events or people that might re-trigger their trauma. Those who have PTSD also have what is called “reactive symptoms.” These symptoms put them on edge, or make them more easily startled, angry, or interfere with their sleep. In addition, people with PTSD also may experience cognition issues, forgetting details of their trauma or having feelings of guilt around it.
Depression & Anxiety
23andMe’s study also found that people with PTSD often also have anxiety or depression, a link found in several other studies.
As part of 23andMe’s research, Henri conducted an environmental-wide association study looking at 200 other health conditions.
Anxiety and depression were most commonly associated with PTSD. Not everyone who has anxiety or depression and goes through trauma ends up with PTSD, but having either of those two conditions more than doubled the odds of being self-diagnosed with PTSD. Yet other conditions were also associated with PTSD, such as insomnia, panic attacks, a disability, and chronic pain. People with PTSD also were more likely to rate their general health lower than those without PTSD.
23andMe’s study did not look at the type or timing of the trauma that led to the PTSD diagnosis. For instance, our study didn’t separate combat veterans or sexual abuse victims. Other studies, including those that looked at combat-related trauma, have shown that the type of trauma often affects the severity of PTSD symptoms. In addition, our study did not discern if those self-diagnosed with PTSD had these mental health conditions before or after suffering the trauma that led to their PTSD.
The significance of clustering other mental health conditions with PTSD is that diagnosing these conditions can sometimes be problematic, said Henri. Many of those with PTSD often have other mental health concerns. Understanding this is important for properly diagnosing and treating those conditions.
“Future studies should look further into the potential for gene-environment interactions that may lead to PTSD diagnosis,” Henri said.
Researchers who are interested in collaborating with 23andMe can find out more here.