Subjective weather sensitivity and physiological stress responses after walking in nature in individuals with coronary artery disease

Background: Stress – both physiological and psychological – is known to affect the biological processes involved in the progression of coronary artery disease (CAD) (Gecaite J. et al., 2019). Recently, increasing attention has been paid to nature’s restorative effects on physiological stress, corroborated by experimental findings over the past three decades (Olafsdottir G. et al., 2020). While individuals generally tend to recover more effectively from stress in natural environments compared to urban ones, nature is not universally restorative (Gatersleben B. et al., 2013). In particular, little is known about the restorative potential of natural environments for individuals who subjectively perceive themselves as being weather-sensitive (WS).

Goals: The study evaluated how subjective weather sensitivity influences physiological stress responses after walking in nature in individuals with CAD.

Subjects and methods. This randomized controlled trial included 71 individuals with CAD (83.1% men and 16.9% women; mean age 59.01±7.48 years), all participating in a cardiac rehabilitation program (Martinaitiene D. et al, 2024). The study assessed self-perceived WS by asking participants, "Do you feel the weather changes?" Those who answered “YES” were classified as “WS”, while the rest were conveniently classified as “non-WS”. On the day of the experiment, participants engaged in a 20-minute walk in a park environment. After their return, we subjected them to the Cold Pressor Test (CPT) to induce acute physiological stress. To assess physiological responses to stress, salivary cortisol concentrations were measured at three points: before walking (T1), immediately after walking (T2), and 20 minutes after a CPT (T3). Cortisol changes within groups were analyzed using the Wilcoxon Signed Ranks Test.

Results. Both WS and non-WS participants showed no significant change at T2 (immediately after the walk in the park). However, both groups showed a significant cortisol increase at T3 (in response to CPT), with a more pronounced change (higher absolute Z-value) in the non-WS. For WS participants, the increase from T1 to T3, and from T2 to T3 correspondingly, were both statistically significant (Z=2.18, p=0.029, median=0.59 and Z=2.55, p=0.011, median=0.87, respectively). Among non-WS participants, the increase from T1 to T3 was more pronounced (Z=3.05, p=0.002, median=1.41) and the rise from T2 to T3 remained significant (Z=3.10, p=0.002, median=0.60).

Conclusion. These results suggest that both subjective weather sensitivity and environmental context may influence physiological responses to stress in individuals with CAD.

Funding: This study was funded by a Grant (No S-MIP-23-114) from the Research Council of Lithuania and was inspired by work from COST Action CA23113 on Climate Change Impacts on Mental Health in Europe (CliMent) and supported by COST Association (European Cooperation in Science and Technology).