Assessing causal links between age at menarche and adolescent mental health: a Mendelian randomisation study [Registered Report Stage 1 Protocol]

ABSTRACT: The timing of puberty may have a substantial impact on adolescent mental health. In particular, earlier age at menarche has been associated with elevated rates of depression in adolescents. Some preliminary evidence suggests that this relationship is causal, but replication and an investigation of the broader generalisability of this finding is warranted. In this Registered Report, we will triangulate different causal inference methods using a new wave of data from the Norwegian Mother, Father and Child Cohort Study (MoBa). We will investigate: (1) to what extent age at menarche is associated with adolescent depression; (2) if associations extend to other domains of mental health; and (3) whether links between age at menarche and mental health are likely to be causal. The findings will elucidate the impact of pubertal timing on mental health and may help inform early detection and prevention. ITEMS: Additional file 1: design table.pdf; Additional file 2: supplementary methods.pdf; Additional file 3: psychometric properties of sympton scales.pdf; Additional file 4: variable overview.pdf; Additional file 5: overview of ALSPAC and MoBa variables for replication; Additional file 6: summary of arrays and batching in genotyping.pdf; Additional file 7: Stage 1 RR Supplementary code.pdf; Additional file 8: results of power analyses.pdf; Letter from data controller.pdf; Stage 1 RR age at menarche.pdf