Adverse life events, sensitization of spinal nociception, and chronic pain risk

Adverse life events (ALEs) are major life stressors that can occur throughout the lifespan and pose a significant physical or psychological threat to safety and/or security. Research suggests there is a link between ALE exposure and the development of chronic pain. Mechanistic animal and human studies indicate that stressors can have a long-lasting sensitization on nociceptive systems. This chapter reviews studies on ALE exposure and nociceptive processing in pain-free individuals to identify changes in nociceptive pathways that might confer chronic pain risk. Together, these studies indicate that ALE exposure accumulates, in a dose-dependent manner, to promote spinal sensitization. This spinal sensitization is not consistently accompanied by hyperalgesia, implying that compensatory pain inhibitory mechanisms are concurrently activated to keep amplified spinal nociception from resulting in amplified pain perception (i.e., latent spinal sensitization). Thus, chronic pain may be initiated by ALE-evoked latent spinal sensitization, followed by events that impair compensatory pain inhibition processes (e.g., additional adversity/stress, advanced age). Suggestions are made for future research.