How peers get under the skin of adolescents.

Adolescence is a highly sensitive period for social development. Although
parents remain an important source for social support and guidance, in
adolescence, individuals increasingly spend time with their peers and become
increasingly sensitive to peer influences. Accordingly, positive peer
experiences (e.g., friendships) have been shown to contribute to prosperous
development, whereas, negative peer experiences (e.g., peer victimization or
rejection) have deleterious long-lasting effects on mental as well as physical
health. These long-lasting effects are striking; yet, the underlying mechanisms
that may explain how peers get *under the skin* are still poorly understood.
One hypothesis that has been put forward is that exposure to (repeated)
negative peer experiences may sensitize the immune system to more strongly
respond to future social stressors (Giletta et al., 2018; Slavich & Irwin,
2014). In other words, adolescents who are rejected and victimized by their
peers may show enhanced inflammatory reactivity to subsequent social stressors
(i.e., neuroinflammatory sensitization hypothesis), which, in turn, may confer
heightened risk for systemic inflammation and subsequent inflammation-related
health problems. The primary goal of this project is to directly test this
hypothesis.

The current study has three main objectives:
- To examine whether past peer experiences at the group (e.g., peer
victimization) and dyadic level (e.g., friendship) influence acute
pro-inflammatory reactivity to a standardized social stressor in adolescents
(ages 14-15 years)
- To examine whether the effects of peer experiences are moderated by
individual differences in personality traits (e.g., rejection sensitivity)
- To examine whether stressor-induced inflammatory responses are associated
with socio-emotional functioning at follow-up, approximately six months later.

There is also a secondary objective, that is
- To examine autonomic nervous system responses (galvanic skin conductance and
electrocardiography [ECG]) and emotional responses to the standardized social
stressor as additional outcomes

Laboratory assessment with repeated measures to examine physiological and
emotional responses to a standardized social stressor.

N/A

There are minimal burden and risks associated with participation, and there is
no risk for any serious event. Participants will be tested in a quiet
designated room of their school.

At baseline, participants will be exposed to a well-validated laboratory-based
social stressor (a modified version of the Trier Social Stress Test (TSST),
which has been previously used among children and adolescents (e.g., Yim, Quas,
Cahill, & Hayakawa, 2010). The TSST is mildly stressful, but no more stressful
than other (social) experiences individuals experience in daily life.

We are especially interested in how cytokine regulation (as a measure of acute
inflammation of the immune system) changes in response to the acute social
stressor. To assess changes in inflammation, we will use dried blood spots,
which is a commonly used and reliable method for assessing inflammation in
youth (McDade, 2014). A trained experimenter will collect two to five drops of
blood (approximately 50 µL per drop) via finger pricks twice (one for a
baseline assessment before the TSST and one approximately 50 minutes after the
TSST). This procedure entails minimal risk for adolescents, as it is minimally
invasive, and is commonly used in practice with newborns. Participants may
experience mild pain in the finger.

Furthermore, we want to assess autonomic nervous system responses during the
social stress test. To do so, galvanic skin conductance response will be
measures (equipement from Movisens [edaMove] and biosemi) and an ECG will be
made (biosemi). These are non-invasive methods to assess physiological
responses, and are expected to constitute minimal risk and discomfort.