How support helps buffer the harmful effects of stress on children

Stress is a pervasive problem for teens. A recent APAStress in America Survey released in 2014 revealed that teens in the United States perceive higher levels of stress than adults, with many reporting that they feel tired due to stress (36%), overwhelmed (31%) or depressed (30%) during the school year. Furthermore, these experiences are associated with unhealthy eating, sleeping, and exercise patterns that may harm their physical and mental health in the future. It is not surprising then that the incidence of many forms of psychopathology spikes during adolescence, with 22.2 % of adolescents experiencing psychiatric disorders with severe impairment and distress (Merikangas et al., 2010). Overlooked at a broad scale but suggested as playing a critical role in the significant changes in adolescents’ stress and risk is the onset of puberty. With this onset come dramatic increases in the activity of stress-response systems and in emotional reactivity (Dahl & Gunnar, 2009). When combined with other profound social, cognitive, and physical changes that accompany the transition to adolescence, this creates the perfect storm for potential problems, but perhaps also an opportune period for potential interventions, as discussed below.

In contrast to a strong focus on adolescence as a risky period of development, less attention has been paid to identifying protective factors that reduce this risk. Perhaps one of the most important -and easily implemented- protective factors is social support from close relationships. The benefits of social support are not unique to adolescence: support facilitates coping with stress and is associated with widespread benefits for physical and mental health across the lifespan(Hostinar, 2015). Social support can block physiological stress responses (e.g., those of the hypothalamic-pituitary-adrenocortical, HPA axis) to otherwise stressful situations in humans and non-human animals (Hostinar, Sullivan, & Gunnar, 2014). For instance, parental presence can completely block increases in the production of the stress hormone cortisol in 12 to 18-month-olds receiving an inoculation, so long as those infants are securely attached to their parents (Gunnar et al., 1996). In adults preparing for a laboratory public-speaking task, a romantic partner present can block cortisol production during the speech itself (Kirschbaum, Klauer, Filipp, & Hellhammer, 1995).

Correlational studies of social support and perceived stress are informative, but their associations do not imply causality, or the timing of effects. When considering parent-child relationships, correlational research also cannot rule out genetic interpretations such that supportive behaviors and well-regulated stress responses might be inherited together, thus explaining the observed associations. Despite this, there is little experimental research examining the stress-buffering effects of social support during late childhood and adolescence. Mentored by my PhD adviser at the University of Minnesota, Megan Gunnar, and in collaboration with graduate student colleagues (Anna Johnson and Jenalee Doom), we recruited participants spanning the pubertal transition (between the ages of 9 and 16) to participate in experimental studies that explored whether parent support retains the ability to block cortisol stress responses during late childhood and adolescence. Some key questions that have emerged have important implications for adolescent development and intervention.

To study the potency of parent support during later development, we invited 81 children (ages 9-10) and adolescents (ages 15-16) for a laboratory experiment involving a public speaking task (Hostinar, Johnson, & Gunnar, 2015). Public speaking is a task most participants rated as stressful. Half the participants in each age group were randomly assigned to receive help and support from their parent when preparing their speech, whereas the other half prepared with a friendly stranger. Nine- and 10-year-old children receiving parent support had their cortisol stress response completely blocked while delivering their speech alone in another room, whereas children who had prepared with the stranger showed a strong cortisol stress response. In contrast, parent support did not have any stress hormone buffering effects for 15-16-year-olds, who exhibited a pronounced increase in salivary cortisol regardless of whether they had prepared with their parent or the stranger (Hostinar, Johnson, & Gunnar, 2015).

In a follow-up study, we examined whether the shift in the effectiveness of parent support to block cortisol stress responses tracks more closely with pubertal stage or age (Doom, Hostinar, VanZomeren-Dohm & Gunnar, 2015). A sample of 11-14-year-olds was invited to the laboratory to engage in the same public-speaking task, after phone screening for markers of pubertal stage. Roughly equal numbers of younger and older, pre/early and mid/late pubertal youth were recruited then randomly assigned within groups to parent or stranger support conditions with half of each age group (11-12.5 years old and 12.5-14 years old) being pre-pubertal or during early stages of puberty, and half being in the mid/late stages of puberty. Our results showed that being in a more advanced pubertal stage was more closely linked with an ineffective parental buffering effect on cortisol responses, whereas age mattered for cortisol recovery such that parental presence hastened recovery only for younger participants.

One interpretation of these findings is that older adolescents may be shifting from a primary reliance on parent support to peer support, at least when it comes to coping with some forms of stress. The implication may be that teens who turn away from parent support but fail to establish close friendships soon after may be left without any social buffers and at risk of experiencing heightened stress. If so, interventions should prioritize bolstering adolescents’ social skills and promoting the development of healthy, mutually supportive relationships, particularly during the transition to puberty.

Our findings suggest that it is crucial to account for developmental timing when designing interventions. Even in highly nurturing families, parent support did not have the same potency in blocking hormonal stressresponses for older adolescents as it did for older children and the youngest adolescents. This finding suggests that parental support should be harnessed to its maximum potential in clinical interventions during early adolescence, but more diverse strategies may be needed with older adolescents.

An important point to consider when timing interventions is that periods of accelerated neurobehavioral reorganization such as adolescence can present challenges and opportunities for growth or for altering existing developmental trajectories. The pubertal recalibration hypothesis (Romeo, 2010; Romeo, Karatsoreos, & McEwen, 2006) and a few recent studies have suggested that adolescence may indeed be a window of higher plasticity, when the effects of early-life adversity are less notable if current circumstances are low-stress (Quevedo et al., 2011) and when major stressors may initiate their own lingering effects on later stress reactivity (Bosch et al., 2012).

More evidence is needed to test the pubertal recalibration hypothesis, but if substantiated,adolescence may be a particularly effective period to intervene, both to take advantage of ongoing plasticity to reverse the negative effects of prior stressors, and to establish new and effective mechanisms for coping with stress that may last a lifetime. For instance, social support and physical activity during adolescence have been shown to weaken the link between stress and later depression (Colman et al., 2014). Helping teenagers form strong, healthy relationships with their peers and promoting physical exercise through school-based interventions might be fruitful avenues to pursue for tipping the balance towards healthier forms of coping with stress, such as social support and exercise. This may pay high dividends over the life course if adolescence is indeed a critical juncture for establishing these behavioral repertoires.

Much of the research described here was conducted with low-risk, high-income samples. A top priority in mySocial Environment and Stress (SES) lab at the University of California –Davis, where I will be starting in 2016, will be to extend this work to children and adolescents at-risk of experiencing chronic stress, specifically youth living in severe poverty and experiencing familial stress. The overarching goal for my future research program will be to identify and characterize mechanisms of action for protective factors against stress in youth across the full range of the socioeconomic spectrum.

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