A new study highlight some reasons why traumatic experiences can lead to depression. The research in Psychiatry Research found evidence that traumatic stress-related impairment in daily functioning and self-medicating with alcohol predict the onset of depression.

“When working with trauma survivors in a mental health setting, one quickly learns it is not uncommon for people with posttraumatic stress disorder (PTSD) to also meet diagnostic criteria for major depressive disorder (MDD) at some point in their life. There are numerous theories as to why these two conditions often co-occur, and I was interested in teasing apart the nature of this relationship in a large, nationally representative sample,” said study author Shannon M. Blakey of the University of North Carolina at Chapel Hill.

To better understand the link between trauma exposure and depressive symptoms, the researchers examined data from the National Epidemiologic Survey on Alcohol and Related Conditions. The nationally-representative study was initial conducted in 2001-2002. The study re-interviewed the original participants three years later.

Blakey and her colleagues analyzed responses from 8,301 adults without prior depression who had experienced a traumatic event, along with a subset of 1,055 individuals who met the full diagnostic criteria for PTSD.

The researchers found that people who said traumatic stress had interfered with their daily activities and who reported self-medicating with alcohol were more likely to develop depression. Those who were younger, female, and reported a greater number of different trauma types were also more likely to develop depression.

“It is important to keep in mind that the ways in which people respond to trauma (and/or cope with their PTSD symptoms) can make a big difference in their well-being moving forward,” Blakey told PsyPost.

“It is very common for PTSD symptoms to interfere with important life domains (such as interpersonal relationships and/or daily activities), and it is also completely reasonable for trauma survivors to turn to coping efforts that are effective in the short-term but nevertheless exacerbate problems in the long-term (such as avoidance and/or using alcohol/drugs to self-medicate their symptoms).”

“Luckily, clinical psychologists have developed brief and effective treatments for a wide array of mental health conditions (see https://www.div12.org/psychological-treatments/).”

The study controlled for a number of risk factors for depression, such as stressful life events. But like all research, it includes some limitations.

“Although these findings shed light on an important topic, there are several limitations that should be kept in mind. For example, it’s possible that people did not accurately remember important aspects about their trauma, PTSD symptoms, alcohol/drug use, or other life events during the study interviews,” Blakey explained.

“We also only had a 3-year window between interviews, so it’s possible that participants may have endorsed different outcomes if we had used a shorter or longer window between interviews. It would be helpful if we had more information about people before their trauma, immediately after their trauma, and then at multiple points in time after their trauma in order to better characterize MDD risk factors in trauma survivors.”

“Although trauma survivors are at increased risk for MDD and other negative outcomes, many people experience truly horrific events and recover naturally, with some time, on their own. PTSD researchers tend to study the negative effects of traumatic events on people’s mental health out of a desire to develop helpful prevention and/or intervention strategies,” Blakey added. “However, it is important to remember that humans are remarkably resilient and many people look back and say their stressful life experiences ultimately helped them become a stronger, better person.”

The study, “Why do trauma survivors become depressed? Testing the behavioral model of depression in a nationally representative sample“, was authored by Shannon M. Blakey, Jennifer Y. Yi, Patrick S. Calhoun, Jean C. Beckham, and Eric B. Elbogen.