Sir

Most seasoned physicians have had the sobering experience of prescribing medications that, despite good intentions, caused bad outcomes. They would call for louder notes of caution than those expressed in the Commentary by Henry Greely and colleagues (Nature 456, 702–705; 2008) when considering the safety of 'cognitive-enhancing' drugs such as Ritalin and Adderall.

The authors do not mention the US Food and Drug Administration warning on the packets of both of these drugs. Printed in capitals in a black box, it includes phrases such as: “amphetamines have a high potential for abuse. Administration of amphetamines for prolonged periods of time may lead to drug dependence ...Misuse of amphetamine may cause sudden death and serious cardiovascular adverse effects.”

This warning does not cover other rare but serious side effects, such as Stevens–Johnson syndrome (a serious skin reaction) or toxic psychosis. Furthermore, the incidence of serious cardiac arrhythmias is likely to be higher in older people with incipient cardiovascular disease — likely consumers of 'healthy' enhancement.

Further reason for caution in advocating neuroenhancers is the disproportionate advantage the drugs, if effective, would confer on the wealthy. The authors' acknowledgment of existing disturbing inequities does not mean that we should add more.

A responsible position would be to call for a moratorium on the use of enhancers until enforceable policies to minimize socioeconomic disparities are in place, research into the use and impact of these drugs is completed, information on risks and benefits is broadly disseminated — and physicians, educators and regulators have articulated professional normative positions.

See also Risks and benefits may turn out to be finely balanced Much ado about cognitive enhancement Recall of learned information may rely on taking drug again Patterns of drug use have varied throughout history Careful use helps me do better research, and society benefits Enhancement means a broader role for physicians