A common heart disease drug may have the unusual side effect of combating racism, a new study has suggested.
According to the study conducted by researchers from the Oxford University, the beta-blocker drug can reduce "subconscious" racism.
The researchers found that people who took propranolol scored significantly lower on a standard test used to detect subconscious racial attitudes, than those who took a placebo.
Propranolol is most often used to reduce high blood pressure by lowering the heart rate, as well as angina and irregular heartbeat. It is also used to manage the physical symptoms of anxiety, and control migraine.
It is thought to work by blocking activation of the peripheral "automatic" nervous system, and in areas of the brain involved with formulating emotional responses, including fear, called the amygdalae.
The researchers believe propranolol reduces racial bias because such subconscious thoughts are triggered by that automatic nervous system.
For the study, they took 36 white student volunteers, gave half a single 40mg dose of propranolol and half a placebo, and asked them all to undertake the Implicit Association Test - designed to test "subtle and spontaneous biased behaviour" - two hours later.
The test requires participants to visually sort particular words like "joy", "evil", "happy" and "glorious", as well as black and white faces, into the correct categories.
"Our results offer new evidence about the processes in the brain that shape implicit racial bias," the Telegraph quoted Sylvia Terbeck, lead author of the study as saying.
"Implicit racial bias can occur even in people with a sincere belief in equality.
"Given the key role that such implicit attitudes appear to play in discrimination against other ethnic groups, and the widespread use of propranolol for medical purposes, our findings are also of considerable ethical interest," Terbeck said.
Chris Chambers from Cardiff University's School of Psychology said that the results of the study should be treated with "extreme caution".
"We don't know whether the drug influenced racial attitudes only or whether it altered implicit brain systems more generally. And we can't rule out the possibility that the effects were due to the drug incidentally reducing heart rate," he said.
"So although interesting, in my view these preliminary results are a long way from suggesting that propranolol specifically influences racial attitudes," he added.
The study has been published in the journal Psychopharmacology.