Objective
Glucocorticoids are released in response to stress and alter cognition and brain function through both rapid, nongenomic and slow, genomic mechanisms. Administration of glucocorticoids in the form of hydrocortisone enhances aspects of learning and memory in individuals with PTSD, but impairs these abilities in healthy individuals. We examine the time-dependent effects of glucocorticoids on cognition in HIV-infected men.
Methods
In a double-blind, placebo-controlled, cross-over study, we examined the time-dependent effects of a single low dose of hydrocortisone (10mg; LDH) on cognition in 45 HIV-infected men. Participants were randomized to receive either LDH or placebo, and one month later were given the opposite treatment. At each intervention session, cognition was assessed 30 minutes (assessing nongenomic effects) and 4 hours (assessing genomic effects) after pill administration. Self-reported stress/anxiety and cortisol/cytokines in saliva were measured throughout each session.
Results
Compared to placebo, LDH doubled salivary cortisol levels. Cortisol returned to baseline 4 hours post-administration. At the 30-minute assessment, LDH enhanced verbal learning compared to placebo. Greater increases in cortisol were associated with greater enhancements in verbal learning. LDH did not affect subjective stress/anxiety or any other cognitive outcomes at the 30-minute or 4-hour time point.
Conclusion
The rapid effects of LDH on verbal learning suggests a nongenomic mechanism by which glucocorticoids can enhance cognition in HIV-infected men. The non-enduring nature of this enhancement may limit its clinical utility, but provides insight into mechanisms underlying the effects of acute glucocorticoids on learning.