title: Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli.
abstract: Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in NAcc responsiveness toward reward cues. Results from both animal and human PET studies indicate that the stress hormone cortisol may be crucial in the interaction between stress and dopaminergic actions. In the present study we therefore investigated whether cortisol mediated the effect of stress on DA-related responses to -subliminal-presentation of reward cues using the Trier Social Stress Test (TSST), which is known to reliably enhance cortisol levels. Young healthy males (n = 37) were randomly assigned to the TSST or control condition. After stress induction, brain activation was assessed using fMRI during a backward-masking paradigm in which potentially rewarding (sexual), emotionally negative and neutral stimuli were presented subliminally, masked by pictures of inanimate objects. A region of interest analysis showed that stress decreased activation in the NAcc in response to masked sexual cues (voxel-corrected, p<05). Furthermore, with mediation analysis it was found that high cortisol levels were related to stronger NAcc activation, showing that cortisol acted as a suppressor variable in the negative relation between stress and NAcc activation. The present findings indicate that cortisol is crucially involved in the relation between stress and the responsiveness of the reward system. Although generally stress decreases activation in the NAcc in response to rewarding stimuli, high stress-induced cortisol levels suppress this relation, and are associated with stronger NAcc activation. Individuals with a high cortisol response to stress might on one hand be protected against reductions in reward sensitivity, which has been linked to anhedonia and depression, but they may ultimately be more vulnerable to increased reward sensitivity, and addictions. Future studies investigating effects of stress on reward sensitivity should take into account the severity of the stressor and the individual cortisol response to stress.
authors.affiliation: Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands; Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands. Electronic address: noei@xs4all.nl.
authors.forename: Nicole Y L
authors.initials: NYL
authors.lastname: Oei
authors.affiliation: Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands; Department of Gynaecology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Both
authors.affiliation: Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands; Netherlands Consortium of Healthy Ageing, The Netherlands.
authors.forename: Diana
authors.initials: D
authors.lastname: van Heemst
authors.affiliation: Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: van der Grond
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D002755:Choice Behavior / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009714:Nucleus Accumbens / Q000502:physiology*; D010775:Photic Stimulation; D012201:Reward; D012463:Saliva / Q000737:chemistry; D012725:Sexual Behavior / Q000502:physiology*; D013315:Stress, Psychological / Q000503:physiopathology*
chemical_list: D006854:Hydrocortisone
keywords: Backward masking; Cortisol; Functional Imaging; Nucleus Accumbens; Reward; Social stress