Psychological Stress on Wound Healing: A Silent Player in a Complex Background

Stress is hard to define and is further complicated by varied perceptions in the population and differing responses in different situations. Psychological stress brings about certain physiological changes through manipulation of the neural, humoral and immunological systems. Observational studies have showed that fear and anxiety before surgery can complicate normal wound healing. Two different pathways appear to be involved: one directly through hypothalamic-pituitary-adrenal axis and sympathetic-adrenomedullary axis, and another indirectly through negative psychological stressors such as anxiety, depression and social isolation. The pathogenesis includes decreased expression of pro-inflammatory cytokines, resulting in poor angiogenesis, matrix regeneration and delayed healing. Prolonged immunological activation in itself is a stressor and can precipitate a sickness behaviour syndrome manifested by disturbed sleep, anorexia, reduction in activity, increased responsiveness to pain and addiction to alcohol and tobacco. It has been observed that cortisol release suppresses pro-inflammatory cytokine release, while down-regulation of cortisol causes unabated inflammatory response. In individuals with chronic wounds, on the other hand, it is thought that physical stress has different effects such as foul odor, pain, exudate and social and familial isolation, which may act independently as psychological stressors. This article attempts to appraise the influence of psychological stress on the immunological system and its effect on wound healing.