Allopregnanolone and Dynamic GABA-A Receptor Plasticity in Selective Serotonin Reuptake Inhibitor Responsive Premenstrual Dysphoric Disorder

Inclusion Criteria: * female sex, * fluent in the English language * regular menstrual cycles (24-35 days) * age 18-50 years old * ability to give written informed consent Exclusion Criteria: * psychiatric medication use in the past 2 months * substance use disorder in the past 6 months * lifetime history of psychotic disorder including schizophrenia * schizoaffective disorder, major depression with psychotic features * history of psychiatric disorder other than PMDD in past year * active suicidal ideation with plan or attempt in past 6 months * steroid hormone or hormonal contraceptive use (except levonorgestrel as emergency contraceptive) in past 2 months * pregnancy in past 6 months * history of brain injury * current or history of endocrine disorder including uncontrolled diabetes or thyroid disease * BMI\>40 * History of arrythmias, severe liver impairment, history of seizure disorder * If currently taking the following meds: methylene blue, linezolid * Other prohibited concomitant meds are Monoamine oxidase inhibitors (MAOIs), pimozide, and disulfiram