Psychological Effects of Musky Compounds: Comparison of Androstadienone with Androstenol and Muscone Suma Jacob, Sheila Garcia, Davinder Hayreh, and Martha K. McClintock 1 Department of Psychology, Institute for Mind and Biology, The University of Chicago, Chicago, Illinois 60637 Received June 7, 2001, revised January 18, 2002, accepted April 11, 2002 Previously, we have shown that 4,16-androstadien-3- one modulates psychological state, reducing negative mood and increasing positive mood (Jacob and Mc- Clintock, 2000; Jacob et al., 2001a). In order to determine whether similar musky compounds also produce these effects, we compared the effects of androstadienone to those of androstenol and muscone, measuring the psy- chological states of 37 participants. Androstenol and muscone were chosen because they too have a musky odor at high concentrations, while androstenol is a ste- roid like androstadienone and muscone is not. In a con- trolled laboratory setting, we conducted a double-blind, within-subject, repeated-measures experiment counter- balanced for order of presentation. Under each partici- pant’s nose, a nanomolar amount of each compound was presented, masked by clove oil to minimize percep- tible olfactory differences. Participants completed a baseline psychological battery and twice again at 25-min intervals after exposure. Androstadienone’s effects on psychological state were unique in comparison with those of androstenol and with muscone. Exposure through passive inhalation, rather than dermal contact, was sufficient for these effects. Although this is addi- tional evidence that androstadienone may be a phero- mone, it is yet to be determined whether humans exude concentrations into the air adequate for social commu- nication or process this chemical information within nat- ural social contexts. © 2002 Elsevier Science (USA) Key Words: chemosignals; pheromone; odor; mood; musky compounds; steroids. Social chemical signals influence physiology, psy- chological state, and behavior in many animal species (McClintock, 2000, 2002). Studying the effects of chemical signals on humans is particularly challeng- ing because human behavior is multiply determined and there are myriad potential chemosignals. These include social odors, both conscious and unconscious, as well as pheromones (McClintock, 2001). Responses to these chemosignals can reflect their odor qualities, such as pungency, familiarity, hedonic valance, level of conscious detection, and recognized source of the stimulus. Previously, we have demonstrated that a particular steroid, 4,16-androstadien-3-one (common name: androstadienone), modulates psychological and physiological variables without conscious detec- tion as an odor (Jacob and McClintock, 2000); Jacob et al., 2001a). The goal of this study was to begin evalu- ating the chemical and olfactory stimulus specificity of androstadienone. Nanomolar amounts of androstadienone affect gen- eral emotional and arousal states, quantified by well- validated measures of psychological state (POMS, ARCI, and VAS scales; (Jacob and McClintock, 2000)). Androstadienone prevents the drop in positive mood and rise of negative mood, which typically occur un- der the odor carrier condition during our experimen- tal protocols. This suggests that androstadienone modulates the physiological mechanisms of emotional states and attention. Indeed, androstadienone alters cerebral glucose utilization in brain areas not typically associated with olfaction, including subcortical re- gions and widespread areas of the neocortex, includ- ing the prefrontal cortex, superior parietal area, and visual cortex (Jacob et al., 2001b). These widely distrib- uted changes are consistent with modulation of an 1 To whom correspondence and reprint requests should be ad- dressed at Department of Psychology, The University of Chicago, 5730 S. Woodlawn Avenue, Chicago, IL 60637. Fax: 773-702-0320. E-mail: mkml@uchicago.edu. Hormones and Behavior 42, 274–283 (2002) doi:10.1006/hbeh.2002.1826 0018-506X/02 $35.00 © 2002 Elsevier Science (USA) All rights reserved. 274