Even minor fender benders can produce enough force to cause a neck injury. Wearing seatbelts is the first important step in preventing injuries associated with car accidents. Rate of speed and direction of impact are important factors, too.
But beyond that, there are some risk factors that can predict chronic disability following a whiplash injury. For example, the intensity of the pain (high) early on after the accident points to a poor recovery process.
Studies show that anyone who suffers from chronic neck and/or head pain (headaches) before a whiplash injury is more likely to have chronic pain and disability after the accident. A previous history of anxiety or depression is also a poor prognostic indicator.
Fear of re-injury or increased pain with movement leads to a phenomenon called fear-avoidance behavior (FAB). Your brother-in-law may be demonstrating some of these behaviors. Behavioral counseling combined with physical therapy can help patients work through some of these fears and catastrophizing attitudes.