Environmental context and cortisol stress responses in weather-sensitive patients with coronary artery disease

Background: Although exposure to natural environments is generally associated with reduced stress, these effects are not universal and may vary depending on individual vulnerability (Olafsdottir G., 2020; Gatersleben B., 2013). The term weather sensitivity (WS) refers to a disruption in well-being and/or an exacerbation of physical symptoms triggered by weather changes (von Mackensen S, 2005), which may influence physiological stress regulation, particularly in individuals with coronary artery disease. Cortisol, a key marker of hypothalamic-pituitary-adrenal (HPA) axis activity, provides an objective indicator of stress reactivity and recovery (Miller WL, 2018; Nader N, 2010). Examining cortisol responses after outdoor versus indoor walking may therefore help clarify how environmental context shapes stress physiology in weather-sensitive cardiac patients. Aim: To examine cortisol stress responses in WS individuals with CAD after outdoor versus indoor walking. Subjects and methods. This randomized controlled trial included 90 weather-sensitive (WS) individuals with CAD (74.4% men and 25.6% women; mean age 59.4 years), all participating in a cardiac rehabilitation program. WS was assessed using a self-reported question ("Do you feel the weather changes?"), and participants who answered "YES" were classified as WS. Participants were randomly assigned to one of two walking conditions: outdoor walking in a natural environment (park) or indoor walking (gym on a treadmill). On the day of the experiment, participants completed a 20-minute walk according to their assigned condition. Acute physiological stress was subsequently induced using the cold pressor test (CPT). Salivary cortisol concentrations were assessed at three times: before walking (T1), after walking (T2), and 20 minutes after the CPT (T3). Within-group cortisol changes across measurement time points were analyzed using the Wilcoxon Signed Ranks Test. Results. Among weather-sensitive (WS) individuals, cortisol response patterns differed depending on the walking environment. In the indoor walking group (n = 48), no statistically significant overall differences in cortisol concentrations across measurement time points were observed (Friedman x2 = 3.487, p = 0.175, W = 0.04). Consistently, post-hoc pairwise comparisons did not reveal significant differences between T1, T2, and T3 measurements, indicating a stable cortisol profile throughout the procedure. In contrast, in the outdoor walking group (n = 42), pairwise comparisons indicated a significant increase in cortisol concentration from T1 to T3 (Z =- 2.177, p = 0.029, r= 0.34), as well as from T2 to T3 (Z =- 2.545, p = 0.011, r= 0.39). No significant change was observed between T1 and T2 (p=0.781). Conclusion. In WS individuals with CAD, physiological stress responses differ according to the walking environment. Outdoor walking was associated with a more pronounced cortisol response to subsequent stress, whereas indoor walking was followed by a relatively stable cortisol profile. These findings suggest that environmental context may play an important role in shaping stress reactivity in WS patients with CAD and highlight the need to consider individual environmental vulnerability when designing rehabilitation and stress-management strategies.