People’s memory of their own post-traumatic stress disorder (PTSD) symptoms is not always consistent over time, according to a new study published in Psychiatry Research. The study found evidence that the recall of past PTSD symptoms is related to current symptom severity.

“Over the last five years or so, we have read dozens of papers about how people can remember their traumatic experiences inconsistently over time,” said stud author Sasha Nahleen, a PhD candidate at Flinders University and member of Dr. Melanie Takarangi’s Forensic and Clinical Cognition Lab.

“For example, when veterans are asked soon after returning home, and again years later, about whether they experienced certain trauma events during their deployment, they often report having experienced more events at the second time-point compared to the first. However, we noticed pretty quickly that there were significantly fewer studies about whether people remember their own trauma-related symptoms and distress consistently over time.”

In the study, the researchers asked 410 sexual assault survivors to report their PTSD symptoms and then recall them 6 months later.

“In our study, female participants were first asked to report their trauma-related symptoms including: 1) persistent re-experiencing of trauma, for example through unwanted memories, flashbacks, and nightmares, 2) avoidance of thoughts or reminders of the trauma, 3) negative thoughts or feelings such as exaggerated feelings of self-blame and isolation, and 4) increased reactivity such as being extra vigilant. Six months later, participants were asked to recall those symptoms,” Nahleen explained.

The researchers observed a small but statistically significant decrease in PTSD severity over time. Participants who did not meet the criteria for a PTSD diagnosis at the six month follow-up tended to recall fewer symptoms than they initially reported. But the opposite was true among participants who were PTSD-positive — they recalled experiencing more symptoms than initially reported.

“Overall, we found that people may draw on how they feel now when they are trying to remember their past reactions to trauma. Specifically, people who are not very distressed by their trauma may remember experiencing fewer symptoms in the past than they initially reported. On the other hand, people who are distressed by their trauma, may remember experiencing more symptoms in the past than they initially reported,” Nahleen told PsyPost.

The study includes some limitations. The researchers were unable to account for some factors that could have influenced the results.

“Like other studies in this area, we could not corroborate participants’ reported trauma and trauma-related symptoms. For practical reasons, we also did not measure all the factors that could influence symptom severity and memory after trauma, such as experiencing other trauma events, traumatic brain injury, levels of cognitive functioning and so on,” Nahleen said.

“Our findings have important implications because they show that people may remember their own trauma-related symptoms inconsistently over time. In the future, we aim to investigate the clinical implications of our findings such as whether it would be useful for clinicians to gather additional corroborating reports of symptoms where possible and sensitively discuss with clients that past symptom severity may not always be as severe as they remember.”

The study, “Current PTSD symptomatology distorts memory for past symptoms“, was authored by Sasha Nahleen, Reginald D.V. Nixon, and Melanie K.T. Takarangi.