In a study with 35 women, who did moderate-intensity aerobic exercise, the blood levels of the endocannabinoid anandamide increased and fear decreased. The study was conducted by investigators of several institutions in the USA. Participant completed a 3-day fear acquisition (day 1), extinction (day 2), and extinction recall (day 3) protocol, in which participants were randomly assigned to complete either moderate-intensity aerobic exercise or a light-intensity control condition following extinction training (day 2).
Circulating concentrations of anandamide and BDNF (brain-derived neurotrophic factor) were found to mediate the relationship between moderate-intensity aerobic exercise and reduced threat expectancy ratings following reinstatement. Authors concluded that exercise induced increases of these 2 substances “appear to play a role in enhancing consolidation of fear extinction learning, thereby leading to reduced threat expectancies following reinstatement among women with PTSD” (post-traumatic stress disorder).
