Stress during development has often been regarded as a potentially disruptive force, capable of inducing disease states if overly prolonged or exceedingly intense. It can also, however, favor resiliency and adaptive processing that are crucial to navigating a human life.

Countless studies have indicated that severe neglect during infancy, both in humans and in laboratory animals, results in long-term abnormal development of biological systems involved in the regulation of emotions. Although this view has fostered considerable theoretical advancements (e.g., the understanding of the fundamental causes of emotional disturbances) and practical improvements (design of experimental models of human disorders), it neglects the functional role played by the stress response system in regulating individual attunement and response to specific environments.

Along with other colleagues, such as Marco Del Giudice, Bruce Ellis and Elizabeth Shirtcliff, I also regard the response to stress as a key driver to individual development. The biological system responsible for physical reactions to a stressor not only coordinates immediate responses to external challenges but also functions as a tool that enables the characterization of an environment as favorable or threatening. Thus—under the assumption that environmental cues encountered early in development predict the challenges the adult individual will face in characterizing the context of different environments—the stress response system promotes long-term adaptive processes that prepare the individual to cope with specific external challenges.

Karen Parker and Dario Maestripieri cogently clarified this view that, in analogy with vaccination, has been termed “stress inoculation theory”. Whilst the fundamental mechanisms linking severe neonatal stress with psychiatric disturbances have been detailed, the potentially positive effects exerted by mild forms of developmental stress have been far less characterized. A recent Special Issue in Neuroscience & Biobehavioral Reviews (partly supported by a NARSAD Grant) attempted to bridge this gap and to clarify the link between developmental stress and adaptive plasticity.

These studies summarize scientific evidence that support the hypothesis that moderate challenges encountered during the early stages of life may ‘prepare’ the individual to cope with future stressors, thus building resiliency. Within this framework, pathological outcomes may occur either as a consequence of extreme stressors exceeding individual adaptive capacities (e.g., infantile neglect or childhood abuse) or under conditions in which the early environmental cues fail to adequately predict the environment the adult lives in. This view may disclose important avenues in the study of human pathologies whereby it offers a novel theoretical framework against which experimental models can be designed.

by Simone Macri, Ph.D.,
2007 NARSAD Young Investigator
Sect. Behavioural Neuroscience, Istituto Superiore di Sanità, Rome, Italy
Simone Macrì, Sect. Behavioural Neuroscience, Istituto Superiore di Sanità, Rome, Italy