Duration and timing interactions of early-life stress and the potential for recovery

Stress comprises three sequential stages: the event (stressor), which leads to an initial effect on a focal organism (stress), followed by the organism's ultimate response (recovery or not). Using this framework, we test how the duration and timing of a stressor individually and interactively affect the initial and asymptotic organism outcomes. We applied either long or short water restrictions either early or later in the life of Lepidium sativum. While several of these water restriction treatments caused a noticeable initial effect, all were able to recover fully, except for those exposed to a long early water restriction. While long early stressors led to decreased height, a growth model revealed that both long and short early stressors changed the rate of growth and prolonged the inflection point, findings that would have been missed had effect and response not been analyzed separately. Both the stressor and the magnitude of the initial effect in part explained the change in the growth model parameter estimates. Overall, timing, duration, and, more importantly, the interaction of these two temporal aspects of stress significantly affects an organism's initial response to a stressor and its ability to ultimately recover from stress. Our findings highlight the importance of explicitly studying the interactions of stressor aspects and of examining the immediate stress effects, as well as long-term responses.