Durk Pearson & Sandy Shaw’s®
Life Extension NewsTM
Volume 15 No. 5 • September 2012


Propranolol, Beta Blocker Used Most Frequently in the Treatment of High Blood Pressure, Found to Reduce Implicit Negative Racial Bias

Just to prove that governments are not always the ones to fund “socially meaningful” scientific studies, we get this gem that was funded by the Wellcome Trust.

The study1 was conducted to help identify underlying neurobiological mechanisms in implicit negative attitudes toward other races. By implicit, the authors mean attitudes that individuals have that they may not be aware of. “It has been suggested, however, that implicit measures best predict subtle and spontaneous biased behavior whereas explicit prejudice measures predict deliberate behavior.”1

The researchers used the IAT, implicit association test, to detect implicit attitudes toward social outgroups that can include race, sexual orientation, gender, or political preference. The authors claim that “IATs were developed precisely to reduce the effect of social desirability responses which might affect explicit prejudice responses.” They say that several studies have suggested that “compared to explicit prejudice, implicit prejudice involves a stronger emotional component.” For example, one study found that there was increased amygdala (a brain area involved in emotional processing) activity when white participants viewed faces of unknown black people, which was said to be confirmed by other studies (citations provided). The magnitude of amygdala activation was correlated with participants’ IAT scores. However, they note that previous studies they cited were largely correlational in nature and, therefore, couldn’t establish causality.

The authors hypothesized that beta-adrenoceptor blockade, which reduces emotionality, both in terms of observable behavior as well as physiological measures such as heart rate and blood pressure, would reduce implicit racial attitudes as measured by the IAT without a corresponding reduction in measures of explicit prejudice.

And, indeed, this is what they found. In their discussion, the authors point out that, since “the amygdala plays a key role in the early non-conscious appraisal of threat … [that it] may therefore also be involved in the mediation of implicit racial prejudice.”1 In support of this, they cite neuroimaging studies in which increased amygdala activation was associated with implicit but not explicit racial attitudes.

The authors note the recent discovery that in-group favoritism is increased by the hormone oxytocin2 and that there are interactions between oxytocin and noradrenaline pathways; they also note that in animals propranolol can lower oxytocin levels.

Studies of this kind can provide some useful information on social behavior, such as prejudices, but they cannot account for the experiential background to an individual’s evaluation of the likely results of interacting with members of “other” groups. A noteworthy example was famously provided when the Rev. Jesse Jackson told an anecdote of how once he was walking through a rough area of a city and, hearing footsteps behind him, turned around and then seeing that it was a group of white people was relieved that they weren’t black. He was not happy about this realization, but admitted that he had in fact experienced a sense of relief. Indeed, most crimes against black people are committed by other black people, which could result in amygdala sensitization to a sense of threat when interacting with blacks especially in “bad” sections of town.

It is also true that one downside of propranolol treatment of high blood pressure is that it tends to cause a general flattening of emotional affect, so it would not be at all surprising if it flattened emotional affect as it relates to implicit racial bias. Finally, one ought, perhaps, to be more concerned with those who are willing to take action against outsider groups, the effectuating of explicit racial bias and here we come to the matter of how one can use the discipline of the criminal law to reduce the incentive to initiate physical aggression against others.

References

  1. Terbeck et al. Propranolol reduces implicit negative racial bias. Psycho­pharmacology DOI 10.1007/s00213–012–2657–5.
  2. see, for example, De Dreu et al. The neuropeptide oxytocin regulates parochial altruism in intergroup conflict among humans. Science 328:1408–1411 (2010); De Dreu et al. Oxytocin promotes human ethnocentrism. Proc Natl Acad Sci USA. J108(4):1262-6 (2011).

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