A new study suggests that the symptomatology of combat-related PTSD is found in small-scale non-Western societies, even when combat is celebrated and social support for warriors is high. However, the results also suggest that depressive symptoms of PTSD are more common in U.S. veterans, possibly due to the violation of culture-specific moral standards against combat. The results were published in the Proceedings of the National Academy of Sciences.

In industrialized societies, members of the armed forces typically develop symptoms of post-traumatic stress disorder (PTSD) – a condition characterized by intense fear, anxiety, and flashbacks surrounding a traumatic event. Throughout the psychology literature, researchers have questioned whether PTSD is a universal disorder with progressive origins or whether the condition is unique to Western societies.

Notably, it has been suggested that combat-related PTSD symptoms might present differently across cultures, perhaps depending on a population’s social norms. To explore this, study authors Matthew R. Zefferman and Sarah Mathew set out to compare the prevalence of PTSD symptoms in a large-scale industrialized society with the prevalence of symptoms in a non-industrialized population. Specifically, the researchers compared the symptoms of PTSD in American veterans and Turkana warriors from a small-scale society in Kenya.

“Turkana communities in this region see cattle raids as an integral part of their livelihoods – without participating in raids, they cannot recover the cattle they lost when they were attacked, and they would be driven from critical dry season pastures and water wells, ”said Mathew.

The U.S. military and Turkana warriors responded to 20 items assessing how often they had experienced a range of PTSD symptoms over the past month. Only respondents who reached the threshold for clinical PTSD were included for analysis.

First, the analysis provided evidence that combat-related PTSD is not unique to industrialized societies. Among those surveyed, 28% of Turkana warriors had PTSD scores above 33, which is considered the clinical cutoff for PTSD among Western samples. However, the pattern of symptoms they exhibited was somewhat different from that of American veterans.

Both groups were about as likely to have symptoms of PTSD as the researchers called ‘learning’ symptoms – symptoms that may have evolved because they help trauma survivors know about acute dangers (eg. , nightmares, flashbacks and reported physical reactions). The two groups were also equally likely to exhibit “reactive” symptoms – symptoms that may have evolved because they teach people to react quickly to danger (eg, hypervigilance). These results suggest that at least some aspects of PTSD have an evolutionary basis and are shared across cultures.

However, Turkana Warriors were less likely than American Veterans to exhibit the five depressive symptoms of detachment, loss of interest, low focus, irritability, and negative feelings. According to Zefferman and Mathew, this suggests that symptoms of depression-like PTSD are influenced by culture.

“The findings provide an evolutionary and cross-cultural informed framework to delve deeper into the origins and causes of moral injuries and their connection to combat-related PTSD,” Zefferman said.

The authors point out that Turkana cultural norms and beliefs likely play a role in reducing the severity of depressive symptoms compared to the U.S. military. Among the Turkana, combat participation is widely supported, combat killings are generally celebrated, and looters are unlikely to expect moral disapproval. In addition, combat is a commonly shared experience.

Among Americans, however, participating in combat is a much more isolated experience. “Most Americans cannot understand the experiences of those who participated in combat,” Zefferman and Mathew write in their study. “Therefore, war presents moral conflict because what is considered the duty of a soldier in combat may violate the moral standards in force within the soldier’s society. American soldiers may therefore have a heightened awareness of the potential social repercussions, especially as they re-enter civilian life. “

Support groups for veterans provide the military with community support and a chance to share their experiences, but these services are unlikely to compare to the social supports in place for Turkana warriors. The authors note that their findings are preliminary and will need to be reinforced by additional longitudinal studies.

The study, “Fighting stress in a small-scale society suggests divergent evolutionary roots for symptoms of post-traumatic stress disorderWas written by Matthew R. Zefferman and Sarah Mathew.