AHS22

Cyclic changes in estrogens and progesterone in mammalian species evolved over thousands of years and eventually developed into what we now refer to as the menstrual cycle. In the 1950s something occurred that natural selection had never anticipated: wide scale distribution of hormonal contraceptives. Today, over 100 million women use hormonal contraceptives, and this number is rapidly growing. Despite this, research on hormonal contraceptives and the brain has only recently emerged. Recent findings have found structural and functional changes in neuroimaging studies of hormonal contraceptive users as well as altered neuroplasticity in animal studies. Most strikingly, studies have reported altered cognitive function and increased depression, anxiety, binge-eating, insomnia, stress, and suicidality among hormonal contraceptive users. From an evolutionary perspective, control over one’s reproductive hormones is a brand-new phenomenon for humans. It’s essential that we consider these drugs in light of evolution in order to understand what unintended consequences they may have.