Objective: Cortisol is elevated in individuals with both increased emotional stress and higher percentages of body fat. Cortisol is also known to affect cognitive performance, particularly spatial processing and working memory. We hypothesized that increased body fat might therefore be associated with decreased performance on a spatial processing task, in response to an acute real-world stressor.
Design: We tested two separate samples of participants undergoing their first (tandem) skydive. In the first sample (N=78), participants were tested for salivary cortisol and state anxiety (Spielberger State Anxiety Scale) during the plane's 15-min ascent to altitude in immediate anticipation of the jump. In a second sample (N=20), participants were tested for salivary cortisol, as well as cardiac variables (heart rate, autonomic regulation through heart rate variability) and performance on a cognitive task of spatial processing, selective attention and working memory.
Results: In response to the skydive, individuals with greater body fat percentages showed significantly increased reactivity for both cortisol (on both samples) and cognition, including decreased accuracy of our task of spatial processing, selective attention and working memory. These cognitive effects were restricted to the stress response and were not found under baseline conditions. There were no body fat interactions with cardiac changes in response to the stressor, suggesting that the cognitive effects were specifically hormone mediated rather than secondary to general activation of the autonomic nervous system.
Conclusions: Our results indicate that, under real-world stress, increased body fat may be associated with endocrine stress vulnerability, with consequences for deleterious cognitive performance.