Hydrocortisone impairs hippocampal-dependent trace eyeblink conditioning in post-traumatic stress disorder

Area of Science:

• Neuroscience
• Psychiatry
• Pharmacology

Background:

• Trace eyeblink conditioning assesses hippocampal function, relevant for Post-traumatic stress disorder (PTSD).
• Glucocorticoids, like hydrocortisone, can modulate this learning task, suggesting a link to PTSD pathophysiology.
• Understanding glucocorticoid sensitivity in PTSD may reveal therapeutic targets.

Purpose of the Study:

• To investigate baseline and hydrocortisone-induced changes in trace eyeblink conditioning in PTSD patients and healthy controls.
• To determine if PTSD is associated with altered glucocorticoid sensitivity in the neural circuits of associative learning.

Main Methods:

• 12 patients with PTSD and 12 healthy controls underwent trace eyeblink conditioning.
• Hydrocortisone (30 mg IV) or placebo was administered 6 hours prior to testing.
• Conditioned response magnitudes and spontaneous blink rates were measured.

Main Results:

• No significant differences in spontaneous blink rates or baseline conditioned responses were observed between groups.
• Following hydrocortisone administration, PTSD patients showed a significant reduction in conditioned response.
• Healthy controls did not exhibit significant changes in conditioned response after hydrocortisone.

Conclusions:

• Patients with PTSD exhibit increased glucocorticoid sensitivity in brain regions mediating trace eyeblink conditioning.
• This heightened sensitivity may contribute to the neurobiological mechanisms underlying PTSD.
• Trace eyeblink conditioning with hydrocortisone challenge is a promising tool for assessing glucocorticoid function in PTSD.