Rejection Sensitivity and Puberty in Mental Health Vulnerability to Social Media Experiences in Early Adolescent Girls - ABSTRACT Research on the social dynamics of social media use in preteen girls is scarce, yet crucial: suicidal thoughts and depression have significantly increased among preteen girls in recent years, and this deterioration of mental health coincides with changes in social media use. Our conceptual model highlights two potential factors that may make preteen girls more susceptible to the negative effects of specific social media experiences: rejection sensitivity and pubertal timing. Online rejection experiences, overt and perceived, are a key component of preteen girls’ social media use that impacts mental health; however, these have not been directly quantified, particularly among those high in rejection sensitivity. Early puberty may be a window of vulnerability to the negative effects of social media use in girls, given the link between early puberty, depression, bullying, and social struggles. To address this, we propose a longitudinal study to examine the bidirectional relations between preteen girls' mental health and social media experiences, exploring psychological and developmental risk factors that strengthen – as well as mitigate – these relationships. This study will recruit a community sample of 250 girls, ages 10-11 years at baseline, to assess their mental health, social media use, rejection sensitivity, and hormone levels over three annual assessments (final age 12-13 years). The study will be the first to include microEMA (8x per day for 14 days, collected via smartwatch) and daily diaries (14 days) to assess preteen girls’ social media use. This approach offers an unparalleled examination of social media engagement, encompassing not only frequency and duration, but also how social media is used in daily life: the temporal unfolding of activities, mood, and social connection and rejection experiences that occur during social media use on a day-to-day basis. Weekly saliva samples will be collected across this period to assess global levels of puberty-related hormones as well as whether weekly hormonal fluctuations are linked to social media use and/or rejection sensitivity. In laboratory clinical interviews, questionnaires, and neural indices of rejection and acceptance sensitivity (EEG) will complement the social media measures. The overarching aim of this study is to examine the relationships between preteen girls' mental health and social media experiences, assessing whether high rejection sensitivity, and puberty impact these relationships; the protective effects of social connection on SM and neural response to acceptance will also be examined. Tests of the hypotheses within each of the aims will be performed through a series multi-level (also known as mixed effects) regression models, including growth models which incorporate time in the study as a variable. Through a detailed and focused assessment of how social media engagement unfolds over time, we will be able to highlight key turning points where elements of problematic social media use commence and persist, leading to the onset or maintenance of psychopathology. These elements of problematic social media use could inform media use guidelines and be future targets for intervention and prevention, particularly in those who may be sensitive to rejection and/or more advanced in pubertal development.
