neuromodulators, serotonin, morality
Recent research in psychopharmacology has highlighted how neuromodulators like serotonin and oxytocin influence social behavior. For instance, serotonin affects people’s propensity to retaliate against unfairness (Crockett 2008, 2010a, 2013), and oxytocin affects people’s willingness to trust others (Kosfeld et al. 2005). In light of these findings, scientists and philosophers have suggested that we might leverage our understanding of the brain to create pharmaceuticals that can enhance moral behavior, and explored the ethical implications of doing so (Crockett 2014; DeGrazia 2014; Persson and Savulescu 2012). In the present article, Levy et al. (2014) raise the concern that widely used pharmaceutical products are already having unintended consequences on moral decision making and behavior. The authors provide a valuable resource by carefully cataloguing existing empirical knowledge about the effects of currently available pharmaceuticals on morally relevant behaviors. Herein, I consider some of their claims and discuss some of the challenges associated with generalizing from the laboratory to the outside world.
Levy et al. review the results of several laboratory studies investigating the effects of pharmaceutical substances on moral decision making and behavior in healthy volunteers. They then suggest that these pharmaceuticals may have similar effects in the large numbers of people who take these same pharmaceuticals on a daily basis for therapeutic reasons, and that such effects could “aggregate to have a serious impact” (Levy et al. 2014, 118). Although such aggregative effects are certainly plausible, there are several reasons one must take caution when generalizing from laboratory studies to the general population. First, the studies Levy et al. describe were conducted in young, healthy volunteers, whereas those who regularly take pharmaceuticals comprise a wider age range and are typically suffering from a psychiatric disorder. Patients with psychiatric disorders usually have neurobiological abnormalities that the medications are thought to normalize in some way; for instance, depressed patients are thought to have dysregulated serotonin function, for which selective serotonin reuptake inhibitor (SSRIs) may [End Page 131] help to compensate (Harmer et al. 2009). Thus, patients on medications may in fact behave more similarly to healthy volunteers on placebo than healthy volunteers on medications.
For illustrative purposes, consider the effects of SSRIs on retaliation against unfairness. This behavior can be measured in the context of an economic game called the ultimatum game, in which one player (the proposer) suggests a way to split a sum of money with another player (the responder). If the responder accepts the offer, both players are paid accordingly; if the responder rejects the offer, neither player receives any money. Many studies have shown that responders retaliate against proposers who make unfair offers by rejecting those offers (Camerer 2003). Healthy volunteers who took a single dose of the SSRI citalopram were less likely to reject unfair offers (Crockett 2010a). However, patients with depression and anxiety taking SSRIs do not seem to show reduced rejection behavior. Two studies have reported that patients on SSRIs do not behave any differently to healthy controls in the ultimatum game (Destoop et al. 2012; Grecucci et al. 2012), whereas another found that medicated patients were more likely to reject unfair offers (Scheele et al. 2013), perhaps reflecting insufficient or incomplete drug action. Thus, it may be the case that unmedicated depressed patients would show abnormally high levels of retaliation, which could be normalized by SSRI medications. Unfortunately, there are no existing data on behavior in ultimatum games with unmedicated depressed patients. However, a study of unmedicated young adults with depressive symptoms (albeit not full-blown clinical depression) showed that they were less likely to reject unfair offers (Harlé et al. 2010), complicating the picture. Adding further complication is the fact that depression and anxiety involve more than abnormal serotonin function, and the precise mechanisms through which SSRIs and other pharmaceuticals alleviate some of the symptoms of mental illness remain unclear. However, based on what we know about the etiology of depression and the few studies that have been conducted in healthy volunteers and patient populations, it is safe to assume that the behavioral effects of pharmaceuticals in healthy volunteers are likely to be different from those...