Reduction of Aversive Learning Rates in Pavlovian Conditioning by Angiotensin II Antagonist Losartan: A Randomized...

Area of Science:

• Neuroscience
• Psychopharmacology
• Behavioral Science

Background:

• Angiotensin receptor blockade is associated with aversive learning and memory.
• It may play a role in preventing posttraumatic stress disorder symptoms.

Purpose of the Study:

• To investigate the effect of the angiotensin receptor blocker losartan on aversive Pavlovian conditioning.
• To explore the influence of losartan on learning dynamics in a probabilistic threat prediction task.

Main Methods:

• Double-blind, randomized, placebo-controlled study with 45 healthy volunteers.
• Participants underwent a probabilistic learning task with changing shock threat levels.
• Computational reinforcement learning models analyzed learning dynamics.

Main Results:

• Losartan significantly reduced participants' adjustment to changing threat levels.
• Aversive learning rates were reduced in the losartan group compared to baseline.
• These effects persisted for 24 hours and were not due to changes in blood pressure or reaction time.

Conclusions:

• Losartan acutely reduces Pavlovian learning in aversive contexts.
• This highlights a potential role for the renin-angiotensin system in anxiety development.