by Dr. Jan Dommerholt, PT, DPT, MPS, DAAPM
Why it is that some people get rear-ended and walk away without any long-term pain problems and others involved in seemingly the same kind of accident, become chronic pain sufferers? Persistent pain and other symptoms are common in a significant number of subjects. Typically, estimates range from 14% to 50% according to some studies, but one classic study suggested that 83% of interviewed subjects involved in a rear-end crash continued to experience symptoms more than 2 years following litigation.
Some lawyers, researchers, and even doctors do not believe that people involved in especially low speed crashes have any reason to develop persistent pain and suggest that these people may suffer from “litigation neurosis”. In other words, they believe that people fake injuries and pain to get more money in a lawsuit or because of psychological issues.
A recent study makes us rethink our assumptions. Researchers at the University of North Carolina School of Medicine have identified a biological reason why some people develop pain and others may not. They found that the injury itself may not be the most important factor, but the person’s stress response may dictate whether that individual is prone to develop chronic pain. The researchers focused on the so-called hypothalamic-pituitary adrenal (HPA) axis, a physiologic system that is directly involved in stress responses. They found that a variation in the gene encoding for one particular protein (referred to as FKBP5) was associated with a 20 percent higher risk of moderate to severe pain six weeks after a motor vehicle accident. In the study researchers looked at victims of sexual assault as well and they were also more likely to develop pain after six weeks of the assault when they had the same gene variation.
In summary, the study clarifies why some people develop persistent pain after experiencing trauma, while others do not. It is not yet clear what this means for therapeutic interventions. We do not know whether therapy, medications, or exercise for example can alter the dysfunctional stress response.
Dr. Jan Dommerholt
Fellow member of the CatchMyPain medical advisory board.
See his bio.