Adrenarche and polycystic ovary syndrome: a tale of two hypotheses.

Polycystic ovary syndrome (PCOS) is an extremely common endocrine disorder affecting young women, with the potential for both reproductive and non-reproductive adverse outcomes. While oligomenorrhea, hyperandrogenism, and cystic ovarian morphology are recognized characteristics of this syndrome, the origin of these disturbances is not always apparent. During normal growth and development, adrenarche, the prepubertal onset of adrenal androgen secretion, results phenotypically in pubarche. Gonadarche, which is the ovarian response to gonadotropin releasing hormone-mediated gonadotropin secretion, also occurs, leading to reproductive competence, namely the establishment of ovulatory cycles, repeatedly. In this mini-review, an overview of adrenarche and gonadarche are presented, followed by two hypotheses. The first describes an evolutionary role for adrenarche: an advantage in the attainment of reproductive competence. The second proposes that the path to PCOS be viewed from a developmental perspective, namely, that PCOS is a maladaptation of the processes that lead to reproductive competence in women. Its defining characteristics of oligomenorrhea, hyperandrogenism, and cystic ovarian morphology are the final common pathway of multiple possible derangements. Elucidating and understanding these maladaptive processes will be the key to future endeavors at prevention and treatment of this common reproductive disorder.