Stress-reactive people are often what outsiders perceive as egocentric, paranoid, volatile, and often become violent in response to perceived threats. Being stress-reactive means you have a low tolerance for threat; and perceived threats will trigger irrational actions and can even destroy health and accelerate aging. (Robert Sapolsky summarizes this research in his bestseller, Why Zebras Don’t Get Ulcers.) In the face of a perceived threat, a stress-reactive individual’s compassion and empathy fly out the window, and self-preservation mode takes over. We often refer to those who default to this mode as being narcissists.
A fantastic article on Psychology Today talks about how stress-reactivity in adults can tear apart society, and it’s foundations form in infancy. One popular method that undermines healthy reactions to stress are methods that encourage parents to not respond to a child’s distress:
[When babies are left to cry, with no parental attempt at timely comforting,] epigenetic effects occur (genes are turned on or off and become part of subsequent cell generation). As a result, brain stress response systems can be wired permanently for oversensitivity and overreactivity (Anisman, Zaharia, Meaney, & Merali., 1998), leading to predispositions for clinical depression and anxiety (Barbas et al., 2003; de Kloet, Sibug, Helmerhorst, & Schmidt, 2005; see Watt & Panksepp, 2009, for a review), poor mental and physical health outcomes, and accelerated aging and mortality (for a review, Preston & de Waal, 2002)
Unrelieved distress in early life reduces the expression of GABA genes, leading to anxiety and depression disorders as well as increased use of alcohol for stress relief (Caldji, Francis, Sharma, Plotsky, & Meaney, 2000; Hsu et al., 2003). When emotional dysregulation becomes chronic, it forms the foundation for further psychopathologies (Cole, Michel & Teti, 1994), especially depression.
Infant emotional dysregulation is related to subsequent mental illness, including a propensity for violence (Davidson, Putnam & Larson, 2000). Stress that leads to “insecure attachment” disrupts emotional functioning, compromises social abilities and can promote a permanent bias towards self-preservation (Henry & Wang, 1998; also see Schore, in press, for a review). Children who are not nurtured well in early life tend to be more stress reactive, aggressive and troublesome.
Bottom line: Parents shape self-control in babyhood with nurturing care. Making sure babies’ needs are met promptly builds calm systems. Parents who don’t respond to baby’s needs lead to systems that are poorly shaped and easily stressed. What the baby’s body “practices” (calmness or distress) becomes habitual.