The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 19 No. 6 • July 2016


A recent paper (Terbeck, 2012) showed that, in a randomized, double-blind, placebo controlled study of 36 white university students (a typical source for participants in these sorts of studies!) were given a single dose of 40 mg. of propranolol, a beta-adrenoceptor antagonist (beta blocker) and their racial bias determined by the IAT (implicit association task). The IAT assesses implicit racial prejudice (the physical expression of prejudice) by an “item sorting task” to distinguish that from explicit racial prejudice, which is limited to what the subject thinks. Explicit racial prejudice was assessed by subjects indicating how “warm” they felt toward various racial groups.

Propranolol is a widely used medication in hypertension and other conditions in which an overactive sympathetic (adrenergic) nervous system is involved.

The results showed that, compared to placebo, “propranolol significantly lowered heart rate and abolished implicit racial bias, without affecting the measure of explicit racial prejudice.” (Terbeck, 2012)

In another fairly recent paper (Kimura, 2011), scientists generated mice without a GPR41 receptor that regulates sympathetic (adrenergic) nervous system activity via the interaction of short chain fatty acids and ketone bodies with the receptor. “...a ketone body, beta-hydroxybutyrate, produced during starvation or diabetes, suppressed SNS [sympathetic nervous system] activity by antagonizing GPR41.”


Kimura et al. Short-chain fatty acids and ketones directly regulate sympathetic nervous system via G protein-coupled receptor 41 (GPR41). Proc Natl Acad Sci U S A. 108(19):8030-5 (2011).

Terbeck et al. Propranolol reduces implicit negative racial bias. Psychopharmacology (Berl). Aug;222(3):419-24 (2012).

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