Sex Differences in Heart-brain Crosstalk - Role of Psychosocial Stress

The main objective of the project is to prospectively determine the influence of sex on amygdalar metabolic activity and myocardial perfusion in a population of healthy postmenopausal women and aged men under acute psychosocial stress conditions.

The primary hypothesis of the study is that women experience disproportionate amygdalar metabolic activity and reduced myocardial perfusion in response to psychosocial stress compared to men.

This project is a monocentric prospective observational study involving hybrid positron emission tomography/magnetic resonance (PET/MR) imaging as well as the collection of biological samples in healthy individuals aged 50-75 years (postmenopausal women, and men). To inflict acute psychosocial stress, the investigators applied the Montreal Imaging Stress Test (MIST) when the participants were inside the PET/MR scanner and the Trier Social Stress Test (TSST) when the participants were outside the PET/MR scanner. Both the TSST and the MIST are standardized tests and are widely applied to provoke reliable biological stress responses in a laboratory setting. No follow-up study is planned. At inclusion, individuals have been interviewed and health data have been collected through questionnaires. In addition, biological samples, including blood, nail and saliva have been collected. Volunteers underwent myocardial blood flow (MBF) and cerebral perfusion imaging using ammonia (13NH3)-PET, as well as functional imaging using magnetic resonance imaging (MRI), both routinely used imaging techniques. 13NH3-PET/MR has been conducted at rest and under stress (MIST). Subsequently, the study participants underwent a TSST, followed by whole body metabolic imaging with fluor-18-deoxyglucose (18F-FDG)-PET/MRI, allowing to study brain and bone marrow metabolism, among other parameters. In parallel, the heart rate response (HRR) has been monitored throughout the study and catecholamines were collected at baseline and after stress to assess the autonomic influence on the heart. The total radiation exposure was below 5 mSv.

In detail, each participant was asked to complete questionnaires to assess their psychometric baseline characteristics at the study visit.

Two blood samples were collected from a peripheral intravenous catheter, at the beginning of the study and the end of the TSST. Blood glucose levels were measured using a finger prick. In addition, saliva samples of approximately 1 mL each were taken at different time points, notably before and after each of the mental stress tests. Nail samples were collected by clipping nails from the fingers and/or toes.