Negative Emotionality and Epigenetics During Puberty

Pubertal transition leads to enduring neuroendocrine changes along with changes in the epigenome. The prevalence of psychiatric disorders significantly increases in females compared to males after puberty. There is likely to be an interaction between epigenetics, hormones and neurophysiological processes during puberty, leading to the increased prevalence of mental disorders in females. This study aims to shed light on these interactions underlying the emerging sex differences after puberty. Specifically, it seeks to investigate the epigenetic modifications and subsequent changes in gene expression during the pubertal transition and their association with negative emotionality (e.g., acute stress response and depressive symptoms) at molecular, neuronal, subjective and physiological levels.

In order to investigate epigenetic and neuroimaging correlates of negative emotionality in pubertal girls, the study employs a cross-sectional design, enrolling 50 pre-pubescent girls (8-10 years) and 50 post-pubescent girls (15-17 years) as healthy participants. Comprehensive data will be collected using self- and parent-report questionnaires on pubertal status, prenatal complications, adverse life events, stress and coping mechanisms, mood and anxiety symptoms, gender identity, and reproductive health. To delve into the neuronal correlates of stress, participants will undergo (f)MRI and MIST. Additionally, physiological stress responses will be assessed through heart rate and skin conductance measurements. Participants will provide blood, saliva, and hair samples for hormone, methylation and expression analysis. DNA methylation analysis will be performed on whole blood and saliva samples using pyrosequencing, focusing on genes that are responsive to estrogen and genes involved in estrogen signaling, based on the previous literature reporting an overrepresentation of estrogen-responsive genes among the differentially methylated sites across the entire genome in girls during puberty. The effects of methylation on gene expression will be measured using reverse transcription real-time PCR. Cortisol levels will be assessed from saliva collected six times during MIST to evaluate the acute stress response and from hair to assess chronic stress. Sex steroids such as estrogen and progesterone from blood will be analyzed using LC-MS/MS. The study aims to provide insights into the intricate relationship between epigenetic modifications, gene expression and negative emotionality (e.g., stress reactivity and internalizing symptoms) during puberty in girls.

Eligibility Criteria:
Inclusion Criteria:

* healthy girls
* aged between 8-10 and having pubertal stage 1 or between 15-17 and having pubertal stage 5
* normal body mass index according to age (between 5th and 85th percentile)
* non-smoking
* German language fluency
* Attending age-appropriate schools

Exclusion Criteria:

* neurological or psychiatric disease
* medical problems such as hormonal, metabolic, developmental or chronic diseases (e.g., congenital disorders, precocious puberty, polycystic ovarian syndrome, diabetes or congestive heart failure)
* any kind of hormonal, pharmacological or psychotropic treatment in the last three months
* engaging in competitive/extreme sports

Additional exclusion criteria for MRI:

* People with non-removable metal objects on or in the body
* Tattoos (if not MRI-incompatible according to expert guidelines)
* Pathological hearing or increased sensitivity to loud noises
* Claustrophobia
* Surgery less than three months ago
* Moderate or severe head injury