The Effects of the Angiotensin II Receptor Antagonist Losartan on Appetitive Versus Aversive Learning: A Randomized Controlled Trial.

What Was Tested

The paper reports a study of Angiotensin II, published as a randomized controlled trial.

The researchers used a reinforcement learning paradigm with compound rewards and punishments to test the prediction that losartan augments learning from appetitive relative to aversive outcomes.

Why It Was Studied

A proposed mechanism of exposure involves inhibitory learning whereby the association between a stimulus and an aversive outcome is suppressed by a new association with an appetitive or neutral outcome.

The blood pressure medication losartan augments fear extinction in rodents and may have similar synergistic effects on human exposure therapy, but the exact cognitive mechanisms underlying these effects remain unknown.

Who Took Part

PubMed indexes the participants as young adults and adults, both men and women.

Participants then performed a reinforcement learning task, which simultaneously probes appetitive and aversive learning.

Participant choice behavior was analyzed using both a standard reinforcement learning model and analysis of choice switching behavior.

How the Study Was Run

The design is described as randomized, double-blind, placebo-controlled and parallel-group.

The participants were allocated by chance, so the Angiotensin II group and the comparison group should start out alike.

As a double-blind Angiotensin II study, the assignments were hidden from both participants and investigators until the end.

The comparison arm used a placebo, so changes seen with Angiotensin II could be set against what happens without it.

The Angiotensin II group and the comparison group ran side by side rather than switching.

What Was Measured

A proposed mechanism of exposure involves inhibitory learning whereby the association between a stimulus and an aversive outcome is suppressed by a new association with an appetitive or neutral outcome.

The subject headings attached to it are Angiotensin Receptor Antagonists, Anxiety Disorders, Appetitive Behavior, Association Learning, Fear, Healthy Volunteers and Implosive Therapy.

The authors tagged it with the keywords Appetitive learning, Aversive learning, Dopamine, Exposure therapy, Fear extinction and Losartan.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of Angiotensin II.

The abstract goes on to report its results in about 4 sentences; this page does not restate them, so read the paper for the findings and their limits.

The publication is from 2019 (Biological psychiatry), a journal based in United States.

More context: the Angiotensin II compound page, all human trials.