Behavioral and Neural Phenotypes of Primary Dysmenorrhea in Adolescents

The study will use primary dysmenorrhea (PD; menstrual pain without an identified organic cause) as a model to examine biomarkers associated with menstrual and non-menstrual bodily pain in adolescent girls, ages 13-19. Participants will undergo extensive phenotyping including pain inhibition testing and multimodal neuroimaging to obtain indices brain structure and function at baseline and 12 months later. Menstrual pain severity and non-menstrual bodily pain will be assessed monthly for 24 months. Aims of the study are: 1) to identify the central mechanisms of PD using measures of pain inhibition and brain structure and connectivity of sensorimotor, default, emotional arousal, and salience networks, 2) to determine deficits in pain inhibition and alterations in brain structure and network connectivity that predict the one-year developmental trajectories of menstrual pain and non-menstrual bodily pain, and 3) to identify the dynamic relationship between alterations in pain inhibition and brain structure and connectivity with symptom change in menstrual pain and non-menstrual bodily pain. We hypothesize that deficits in endogenous pain inhibition and alterations in brain structure, connectivity, and function of regional networks will be positively associated with menstrual pain severity ratings at baseline and predict the trajectory of menstrual and non-menstrual bodily pain over 2 years. The results are expected to identify specific mechanisms and characteristics that predict the transition from acute/cyclical pain to persistent or chronic pain, which will support the development of therapies to prevent the transition from recurrent to chronic pain in adulthood.