Many people, including those suffering from post traumatic stress disorder (PTSD), would welcome a pill that could erase painful memories. Two new studies have re-ignited the debate about the pros and cons of such 'amnesic' drugs.

Propranolol is commonly used to treat hypertension, but it can also weaken memories of a traumatic experience when given shortly after the event. Now, researchers at McGill University in Canada and Harvard University in the United States have shown that the same effect can be observed if propranolol is given while subjects recall events that happened 10 years previously. Karim Nader, one of the authors, says that treatment “...turns down the emotional part ... they could still remember all the details but without being overwhelmed...” (Telegraph.co.uk, 1 July 2007).

Meanwhile, researchers at New York University eliminated a single memory in rats using another drug, U0126, without disrupting other memories. Joseph LeDoux, who headed the study, says that the effects of these drugs could be both “...specific and potentially permanent” (Telegraph.co.uk, 1 July 2007).

However, several commentators urged caution, pointing out that bad memories can be helpful. “Fear reactions are there to protect people from danger in the future”, according to Chris Brown of University College London (BBC News Online, 3 July 2007). Indeed, Linda Blair, a fellow of the British Psychological Society, asks whether the treatment might “...cause more distress than it will relieve” (Guardian Unlimited, 4 July 2007), and Monica Thompson of the Traumatic Stress Clinic says that patients with PTSD could “...be left with potentially debilitating symptoms, such as high fear levels” (BBC News Online 3 July 2007). Others highlighted the need for such drugs to be regulated, to prevent their use by those without medically identified conditions.