Examining the longitudinal associations between negative peer experiences on adolescent inflammation

Most people can recall at least one episode from their youth in which they felt
like they did not belong to their peers. For humans, as well as many other
mammalian species, the adolescent period is characterized by a unique
sensitivity and orientation toward peers, and episodes of peer exclusion and
rejection can *stick in our minds*. For some youth, these experiences are so
stressful that they pose deleterious long-lasting consequences for physical and
mental health. How is this possible? Can negative peer experiences change the
way our body functions, at the molecular level? Although psychoneuroimmunology
research suggests that social stressors might get biologically embedded by
altering immune functioning, in developmental psychology surprisingly little
attention has been devoted to the links between negative peer experiences and
inflammation * the primary response of the immune system.

The main objective of this study is twofold:
1) To investigate the additive and interactive effects between negative peer
experiences at the group level (i.e., peer victimization, peer rejection) and
at the dyadic level (e.g., friendship) on adolescent systemic inflammation.
2) To examine whether negative peer experiences more strongly predict elevated
inflammation among interpersonally sensitive adolescents, who are cognitively
disposed to enhanced perception of social threat.

The secondary objectives of the study are:
1) To investigate the longitudinal associations between inflammation and
depressive symptoms.
2) To investigate the possible transactional effects between peer adversity,
inflammation and internalizing symptoms.
3) To examine the relationship between self-conscious emotions, in particular
shame, and inflammation.

Multi-wave longitudinal design, with 4 assessments occurring every six months,
beginning in the fall of the first year of high school.

The extent of burden and risks associated with participation in the proposed
study are minimal. At each of the 4 assessment waves, participants will
complete three main tasks in a designated classroom of their school. Overall,
the data collection will last approximately 60 minutes. First, participants
will complete a peer nomination procedure, a methodology widely used in
developmental psychology research to assess youth social relations (e.g.,
friendships, victimization). Second, they will fill in a series of standard and
age-appropriate self-reported measures, to assess constructs such as emotions,
internalizing symptoms and interpersonal sensitivity. Third, a trained research
assistant will collect 2 to 5 drops of blood (approximately 50 µl per drop) via
finger prick, a procedure regarded as minimally invasive by medical
practitioners and scientist. Blood collection via finger prick is a commonly
used practice with newborns; as such, this procedure entails even fewer risks
among adolescents. The main advantage of dried blood spots, as collected via
finger prick, is that they provide an appropriate and minimally invasive
procedure to reliably assess inflammation in youth (McDade, 2014). Indeed prior
work has shown correlations higher than .95 between hsCRP assessed via
venipuncture * the gold standard procedure * and via dried blood spots (McDade,
2014).
Notably, adolescence is a particularly sensitive developmental period, in which
the increase in social stressors (e.g., peer adversity) and the heightened
sensitivity and reactivity to these stressors, make some youth at high risk for
elevated inflammation, already so early in life. Thus, examining the course of
inflammation in adolescence is of primary importance to gain knowledge about
early-life risk factors and eventually to inform intervention and prevention
programs aimed at buffering the long-term effects of heightened inflammation
(e.g., heightened risk of heart diseases). As such, the benefits of
understanding these processes in adolescence largely outweigh the minimal risks
associated with this study procedures.