September 25, 2018
HORMONAL CONTRACEPTION, STRESS, AND COGNITION
Hormonal contraception is a form of modern contraception used by women throughout the world. Probably the most well-known form of hormonal contraception is the combined oral contraceptive pill. The combined oral contraceptive pill contains synthetic forms of estrogen and progesterone and acts to inhibit ovulation. Hormonal contraception achieves this by preventing the luteinizing hormone spike that triggers ovulation. This also prevents the characteristic increase in progesterone during the second half of the menstrual cycle. In fact, a general consequence of hormonal contraception use, despite the presence of synthetic estrogen and progesterone in the medication, is keeping levels of estrogen and progesterone at low levels.
Why would the action of hormonal contraception to modify the normal menstrual cycle hormone profile affect stress and cognition? As discussed in the Stress and Sex Hormones section, the stress and sex hormone systems interact and influence one another. As a result of this bidirectional relationship between the two systems, the stress response differs across the menstrual cycle, with women showing larger cortisol responses to stress during the high-hormone luteal phase compared to the low-hormone follicular phase. Thus, if hormonal contraception keeps sex hormones at low levels it would be expected that the stress response would also differ.
Based on the patterns during the natural menstrual cycle, it would be likely that women using hormonal contraception would show smaller cortisol responses to stress than women not using hormonal contraception. In fact, this is the observed pattern. Women using hormonal contraception consistently show smaller cortisol responses to stress than non-users. This has been shown across different types of laboratory stressors, ranging from the physical stress of holding one hand in ice-cold water to verbal arithmetic in front of an audience and a short speech with only few minutes to prepare.
Hormonal contraceptive use also influences learning and memory. This is very evident when looking at memory for emotional informational. Often times, when looking at memory for complex emotional stories in the laboratory, memory items will be categorized as either detail items (items that have no bearing on the central theme of the story) or gist items (items that cannot be changed without affecting the central theme of the story). For example, the gist of a story could be a mother and son walking to school, whereas the details of the story would be additional items, like the name of the street the school is on or what kind of street sign is at near the school’s entrance. These details items, though adding depth to the story, have no impact on the central theme of the mother and son walking to school.
When memory items are broken down into these gist and detail items, sex differences appear with men showing better memory for gist items and women for detail items. Sex hormones appear to contribute to this difference. For instance, women using hormonal contraception tend to show memory patterns more similar to men, presumably related to the effect of hormonal contraception on blunting female sex hormones.
Together, the evidence suggests that hormonal contraceptive use alters the stress response and memory for emotional information, however little work has investigated how hormonal contraception might impact other forms of learning and memory, how these effects may impact subsequent effects of stress on cognition, or the underlying neural mechanisms of these effects. My current research aims to address these questions. For previously presented preliminary results see presentations made at Neuroscience 2017, WCBR 2018 (pg. 156), and upcoming at, Neuroscience 2018.