Psychobiological mechanisms of socioeconomic differences in health.

The association between low socioeconomic status and poor health is well established. Empirical studies suggest that psychosocial factors are important mediators for these effects, and that the effects are mediated by psychobiological mechanisms related to stress physiology. The objective of this paper is to explore these psychobiological mechanisms. Psychobiological responses to environmental challenges depend on acquired expectancies (learning) of the relations between responses and stimuli. The stress response occurs whenever an individual is faced with a challenge. It is an essential element in the total adaptive system of the body, and necessary for adaptation, performance and survival. However, a period of recovery is necessary to rebalance and to manage new demands. Individuals with low social status report more environmental challenges and less psychosocial resources. This may lead to vicious circles of learning to expect negative outcomes, loss of coping ability, strain, hopelessness and chronic stress. This type of learning may interfere with the recovery processes, leading to sustained psychobiological activation and loss of dynamic capacity to respond to new challenges. Psychobiological responses and health effects in humans and animals depend on combinations of demands and expected outcomes (coping, control). In studies of humans with chronic psychosocial stress, and low SES, cortisol baseline levels were raised, and the cortisol response to acute stress attenuated. Low job control was associated with insufficient recovery of catecholamines and cortisol, and a range of negative health effects. Biological effects of choice of lifestyle, which also depends on the acquired outcome expectancies, reinforce these direct psychobiological effects on health. The paper concludes that sustained activation and loss of capacity to respond to a novel stressor could be a cause of the higher risk of illness and disease found among people with lower SES.