The catecholamine neurotransmitter precursor tyrosine increases anger during exposure to severe psychological stress

Abstract

RationaleAcute stress produces behavioral and physiological changes modulated by central catecholamines (CA). Stress increases CA activity, and depletion of CA stores reduces responses to stress. Increasing CA activity by administration of the dietary amino acid CA precursor tyrosine may increase responsiveness to stress. This study determined whether tyrosine enhances the ability of humans to respond to severe stress.MethodsSevere psychological stress was generated during training at Survival, Evasion, Resistance, and Escape (SERE) School. The acute stressor consisted of two mock interrogations conducted during several days of simulated captivity. Seventy-eight healthy male and female military personnel participated in this double-blind, between-subjects study, in which they received either tyrosine (300 mg/kg, N = 36) or placebo (N = 36). Tyrosine (or placebo) was administered in food bars in two doses of 150 mg/kg each approximately 60 min before each mock interrogation. Mood (Profile of Mood States), saliva cortisol, and heart rate (HR) were assessed prior to stress exposure during a week of academic training preceding mock captivity and immediately following the mock interrogations.ResultsThe severe stress produced robust effects on mood (i.e., increased tension, depression, anger, fatigue, vigor, and confusion; p < .001), cortisol, and HR (p < .001). Tyrosine increased anger (p = .002, ANOVA treatment condition by test session interaction) during stress but had no other effects.ConclusionTyrosine did not alter most subjective or physiological responses to severe acute stress, but it increased ratings of anger. The modest increase in anger may be an adaptive emotional response in stressful environments.

The effects of captivity survival training on mood, dissociation, PTSD symptoms, cognitive performance and stress hormones

“…As predicted, we also observed a curvilinear relationship between the four measurement time points and salivary cortisol and DHEA levels. These results are generally consistent with the findings obtained from SERE schools in the U.S., and suggest the observed elevations in salivary markers of stress associated with exposure to CAC training are also transient, returning to baseline or near baseline levels at Recovery/Debriefing (7,9,(12)(13)(14). The hormonal findings from the assays of salivary cortisol and DHEA levels are consistent with the changes in mood, fatigue, dissociation and PTSD symptoms observed and demonstrate CAC training induces acute stress.…”

“…Based on results of similar studies conducted in the U.S. (1,(6)(7)(8)(9)(10)(12)(13)(14), our first prediction was that, compared to baseline, CAC training would cause significant, reversible perturbations in measures of psychological functioning and in specific stress hormone levels known to be relevant to models of stress hardiness and vulnerability. Specifically, consistent with previous scientific research at SERE, our first prediction was that CAC training would, compared to baseline levels of performance: (1) impair cognitive functioning as measured by the Scale, and (6) increase cortisol and DHEA levels.…”

“…Finally, because the nature of the stress is highly realistic and intense, the effects of stress on human function can be studied with high external validity. A large body of data exists that characterizes the effects of SERE training on both the psychological performance and neurobiological responses of participants to stress (1,(6)(7)(8)(9)(10)(11)(12)(13)(14). Because key features of CAC training are modeled on U.S. SERE training, the findings from U.S. SERE studies can form the basis for generating predictions about possible effects of CAC training on psychological and physiological function.…”

The Effects of an Online Mind-Body Training Program on Stress, Coping Strategies, Emotional Intelligence, Resilience and Psychological State

“…Our participants also exhibited a decrease in the negative effect commonly associated with stress. It has been found that severe stress induces anger [ 47 ]; the decrease in anger and negative affect we observed among our participants in the 8-week program seems to be associated with the reduction of stress they exhibited. Furthermore, lower negative affect was associated with greater emotional intelligence [ 48 ].…”

Gene Expression Analysis of Fibroblasts from Patients with Bipolar Disorder

“…These findings may explain the alterations observed in tyrosine transport mechanisms in bipolar type-1 disorder, implying an abnormal access of tyrosine in the brain that could lead to dysfunctional neurotransmitter systems [62].…”