- Brouillard A et al (2023): Morphologic alterations of the fear circuitry: the role of sex hormones and oral contraceptives. Front. Endocrinol. 14:1228504. doi: 10.3389/fendo.2023.1228504
Anxiety is a central basic emotion that can be vital for survival. Excessive anxiety reactions, on the other hand, which have lost their real connection, are very stressful both psychologically and socially. Anxiety disorders are characterised by inadequate emotion regulation, which leads to the maintenance of anxiety symptoms. They occur more frequently in women. Could this also be due to the pill? This is not an easy answer.
For their study, the Canadian research team recruited healthy adults aged between 23 and 35, including women who were currently taking the pill:
In this comprehensive study, which was part of a larger research project, structural and functional MRI examinations were used to search for brain morphological correlates of oral contraceptive use.
This revealed two main abnormalities:
1. Grey matter volume (GMV)
In the area of the dorsal anterior cingulate cortex (dACC), all three groups of women showed a larger GMV than the men. The region is associated with the expression and evaluation of anxiety and is considered to promote anxiety. The larger the volume, the stronger the influence. This correlation has already been shown in anxiety patients.
2. Cortical thickness (CT)
Changes in the area of the ventromedial prefrontal cortex (vmPFC) were visible here, but this time only in women who were currently using hormonal contraception. The region was thinner in them than in the group of men and the other women. In contrast to the dACC, the vmPFC inhibits anxiety. The thicker the region, the better fear extinction and resilience function after trauma exposure and the lower the risk of generalisation of fear.
The researchers draw the following conclusions: Firstly, there appear to be fundamental gender differences in anxiety-related psychopathologies. What has already been empirically investigated could now be explained in terms of brain morphology on the basis of the results: The larger dAAC volume in women may represent a female predisposition to anxiety disorders.
On the other hand, this increased susceptibility could be exacerbated by the use of oral contraceptives. This is supported by the thinning of the anxiety-inhibiting region of the vmPFC alone in women who are currently taking the pill. As the change was not observed in former users, the effect appears to be reversible.
However, the scientists point out that caution is required when interpreting the correlation between brain morphology and behaviour. The emotional circuits are too complex and multifactorial to be traced back to a single mechanism.
The pill could influence key regions in the brain that are involved in the development and regulation of anxiety. Especially during adolescence, when the nervous system is still developing, exogenous hormones could sensitise certain areas. This should be taken into account when considering which contraceptive method is best for young women.