commentary 2002 Nature Publishing Group http www nature com natureneuroscience Emerging ethical issues in neuroscience Martha J Farah There is growing public awareness of the ethical issues raised by progress in many areas of neuroscience This commentary reviews the issues which are triaged in terms of their novelty and their imminence with an exploration of the relevant ethical principles in each case In less than a year neuroethics has joined the vocabulary of most neuroscientists Exactly what the word signifies may not be clear to most of us however Both the word and the field to which it refers come largely from individuals outside neuroscience Newspaper columnist William Safire gave the field its name and defining statements of the issues are found in such sources as Brain Policy1 by bioethicist Robert Blank Our Posthuman Future2 by historian Francis Fukuyama and a cover story in The Economist magazine May 23 2002 Neuroscientists themselves have been relatively scarce in public discourse on neuroethics perhaps because many of the issues under discussion seem far fetched Need we devote serious attention now to the needs and rights of cyborg humans with computeraugmented brains Probably not given the current state of technology Yet neuroscientists are just the people to guide the discussion toward issues of current and near term priority How does neuroethics as presented to us in the literature relate to the current state of neuroscience and its foreseeable future Here I attempt to triage the issues that have been raised separating those that are both new and immediate from those that are not new or are likely to arise only in the distant future Although all three categories deserve our continued attention the first poses the most immediate intellectual and social challenges Three broad issues survive the triage for novelty and imminence enhancement of normal function court ordered CNS intervention and brain reading Each emerges from work in multiple areas of neuroscience from molecular to cognitive neuroscience The nature of the ethMartha Farah is at the Center for Cognitive Neuroscience University of Pennsylvania 3815 Walnut St Philadelphia Pennsylvania 19104 6196 USA e mail mfarah psych upenn edu ical issues raised are similarly varied and include the rights to equal opportunity privacy and freedom Enhancement of normal function If drugs and other forms of central nervous system intervention can be used to improve the mood cognition or behavior of people with problems in these areas what might they do for normal individuals Some treatments can be viewed as normalizers which have little or no effect on systems that are already normal for instance the mood stablizer lithium3 and will not therefore figure in debates over enhancement Other treatments can indeed make normal people better than normal Pharmacological enhancement is arguably being practiced now in several psychological domains enhancement of mood cognition and vegetative functions including sleep appetite and sex The enhancement potential of some psychiatric treatments is in itself nothing new Until recently however psychotropic medications had significant risks and side effects that made them attractive only as an alternative to illness With our growing understanding of neurotransmission at a molecular level it has been possible to design more selective drugs with better side effect profiles In addition adjuvant therapy with other drugs is increasingly used to counteract the remaining side effects For example the most troublesome side effect for users of selective seratonin reuptake inhibitors SSRIs is sexual dysfunction which responds well to the drug sildenafil Viagra Other drugs specifically developed to counteract the sexual side effects of SSRIs are in development and clinical trials Vernalis press release May 22 2002 The result of both new designer drugs and adjuvant drugs is the same increasingly selective neurochemical alteration of our mental states and abilities Peter Kramer s book Listening to Prozac4 first focused society s attention on nature neuroscience volume 5 no 11 november 2002 the possibility of safe mood enhancement The growth in sales of SSRIs clearly indicates that more people with less severe depression are using them Has the threshold for SSRI use dropped below the line separating the healthy from the sick This question is hard to answer for several reasons First the line between healthy and sick is a fuzzy and perhaps arbitrary one There is no simple discontinuity between the characteristic mood of patients with diagnosable mood disorders and the range of moods found in the general population 5 Second diagnostic thresholds are clearly moving downward as a result of these very changes in treatment For a given severity of illness the better tolerated the treatment the more likely patients are to present for diagnosis and the more likely physicians are to diagnose and treat As a related point other more common and less debilitating conditions are also being treated with SSRIs such as cyclic changes in women s moods before menstruation6 Third although depression is usually a remitting relapsing disease with typically years between episodes patients today are likely to be treated prophylactically with antidepressant medication for periods of 1 3 years even when symptom free7 Thus there are many people now on antidepressant medication who are healthy with only a vulnerability to depression as opposed to depression These changes in psychiatric practice have resulted in many people using SSRIs and other antidepressants who would not have been prescribed these drugs ten years ago There is no reason to predict their ranks will not continue to swell and to include healthier and higher functioning people What changes might healthy individuals hope to experience through the use of antidepressant medication Mood enhancement belongs on the docket of new and imminent bioethical issues in neuroscience only if current and foreseeable medications can deliver pleasing 1123 2002 Nature Publishing Group http www nature com natureneuroscience commentary results to healthy people A handful of studies have assessed the effects of SSRIs on mood and personality in normal subjects over short periods of a few months or less for example refs 8 9 The effects are relatively selective reducing selfreported negative affect such as fear hostility while leaving positive affect happiness excitement the same The drugs also