Neonatal Hair Cortisol and Birth Outcomes: An Empirical Study and Meta-Analysis.

OBJECTIVE: Prenatal stress physiology is often posited as a predictor of birth outcomes, including gestational age at birth and birthweight. However, research has predominantly relied on indicators in the maternal system, with few studies examining hormones of the fetal system. The current study focuses on fetal cortisol in the third trimester, as measured in neonatal hair, as a biological factor that might be associated with birth outcomes (gestational age at birth and birthweight). We report findings from two studies: a longitudinal cohort (Study 1), and a meta-analysis of the existing literature (Study 2). METHODSSTUDY: Hair was collected for cortisol analysis from 168 neonates (55.95% female) shortly after birth. Gestational age at birth and birthweight were abstracted from medical records. METHODSSTUDY: An exhaustive search of four databases was conducted, yielding 155 total studies for screening. Papers reporting neonatal hair cortisol (collection <2 weeks postpartum) and birth outcomes among human neonates were retained for analysis, including Study 1 results ( k = 9). RESULTSSTUDY: Higher neonatal hair cortisol was related to longer gestation ( r = 0.28, p < .001) and higher birthweight, r = 0.16, p = .040. Sex did not moderate either association. RESULTSSTUDY: Across the nine studies, higher neonatal hair cortisol predicted both longer gestation ( r = 0.35, p < .001, 95% confidence interval = 0.24-0.45) and higher birthweight ( r = 0.18, p = .001, 95% confidence interval = 0.07-0.28). Neonatal sex did not moderate these associations. CONCLUSIONS: Fetal cortisol exposure in the third trimester plays a role in normative maturation of the fetus, and findings reveal that higher cortisol is associated with positive birth outcomes.

Immune response and intergroup bias: Vaccine-induced increases in cytokine activity are associated with worse evaluations of resume for Latina job applicant.

Situational factors can increase people's vulnerability to intergroup bias, including prejudicial attitudes, negative stereotyping, and discrimination. We proposed that increases in inflammatory activity that coincide with acute illness may represent a hitherto unstudied situational factor that increases intergroup bias. The current study experimentally manipulated increases in inflammatory activity by administering the seasonal influenza vaccine or a saline placebo. We quantified inflammatory activity by assessing change in salivary pro-inflammatory cytokines and assessed intergroup bias using a resume evaluation task and self-reported ethnocentrism. Primary analyses focused on a subsample of 117 participants who provided high quality data; robustness analyses included various permutations of lower quality participants. Findings revealed that changes in the cytokine interleukin-1ß (IL-1ß) in response to the vaccine were associated with greater intergroup bias. Among participants who received the vaccine, IL-1ß change was negatively associated with evaluation of a Latina (but not a White woman) applicant's competency and recommended starting salary. Moreover, IL-1ß change was positively associated with ethnocentrism. Overall, results provide support for the hypothesis that acute illness, via the mechanistic role of inflammatory cytokines, affects social cognition in ways that can increase intergroup bias.

A mismatch between early and recent life stress predicts better response inhibition, but not cognitive inhibition.

A growing body of work has found that a mismatch between early and recent life stress, more than a cumulative influence of stress, contributes to detrimental stress-related health outcomes. To date, however, no work has examined how such a mismatch might relate to stress-related cognitive outcomes. We addressed this gap in the current study by assessing participants' (N = 154, Mage = 18.7, 104 female) early and recent life stress using the same inventory, and subsequently assessing their inhibitory control in a hybrid stop-signal/flanker task. Surprisingly, we found that a greater degree of stressor mismatch was associated with better response inhibition (i.e. smaller stop-signal reaction time) across a number of analytic approaches. Cognitive inhibition (i.e. the flanker interference effect) was not associated with stressor mismatch. These results thus show that a greater degree of mismatch between early and recent life stress is related to response inhibition in the same way as acute stress affects response inhibition, suggesting that response inhibition may be an important cognitive process for navigating both acute stress and general environmental conditions that do not match the conditions in which expected stress occurrence was established.

The effects of acute versus repeated cannabidiol administration on trauma-relevant emotional reactivity: A double-blind, randomized, placebo-controlled trial.

Despite the widespread use and perceived efficacy of cannabidiol (CBD) as an anxiolytic, few controlled studies have evaluated the effects of CBD on anxiety-relevant indications, and only one has done so in the context of trauma-related symptoms. The current study was designed to address this gap in the literature. Participants were 42 trauma-exposed individuals (Mage = 23.12 years, SDage = 6.61) who endorsed elevated stress. They were randomly assigned to take 300 mg of oral CBD or placebo daily for 1 week. Acute (i.e., following an initial 300 mg dose) and repeated (i.e., following 1 week of daily 300 mg dosing) effects of CBD were evaluated in relation to indicators of anxious arousal (i.e., anxiety, distress, heart rate) in response to idiographic trauma script presentation. The results of the current study suggest that relative to placebo, 300 mg CBD did not significantly reduce anxiety, B = 13.37, t(37) = 1.71, p = .096, d = 0.09, Bayes factor (BF10) = 0.54; distress, B = 15.20, t(37) = 1.31, p = .197, d = 0.07, BF10 = 0.51; or heart rate, B = -1.09, t(36) = -0.32, p = .755, d = 0.02, BF10 = 0.29, evoked by idiographic trauma script presentation in the context of acute or repeated administration. These data suggest that CBD may not effectively reduce trauma-relevant emotional arousal; however, more work is needed to confidently assert such claims due to the small sample size. The current study extends the groundwork for additional studies in this important area.

When stress enhances memory encoding: The beneficial effects of changing context.

The effects of acute stress on memory encoding are complex, and we do not yet know all of the conditions that can determine whether stress at encoding improves or impairs memory. Recent work has found that changing contexts between encoding and stress can abolish the effects of post-encoding stress on memory, suggesting that context may play an important role in the effects of stress on memory. However, the role of context in the effects of stress on memory encoding is not yet known. We addressed this gap by examining the effects of context on the influence of acute stress on memory encoding. In a 2 × 2 experimental design, participants (N = 103) completed either a stressor (i.e., Socially Evaluated Cold Presser Test) or control task (i.e., warm water control) before completing a memory encoding task, which occurred in either in the same room as or a different room from the stressor or control task. Memory retrieval was tested for each participant within the context that they completed the encoding task. We found that, relative to nonstressed (i.e., control) participants, stressed participants who switched contexts prior to encoding showed better memory for both negative and neutral images. In contrast, when the stressor or control task occurred in the same room as memory encoding, stress had no beneficial effect on memory. These results highlight the importance of the ongoing context as a determinant of the effects of stress on memory encoding and present a challenge to current theoretical accounts of stress and memory.

Cumulative lifetime acute stressor exposure interacts with reward responsiveness to predict longitudinal increases in depression severity in adolescence.

BACKGROUND: Life stress and blunted reward processing each have been associated with the onset and maintenance of major depressive disorder. However, much of this work has been cross-sectional, conducted in separate lines of inquiry, and focused on recent life stressor exposure, despite the fact that theories of depression posit that stressors can have cumulative effects over the lifespan. To address these limitations, we investigated whether acute and chronic stressors occurring over the lifespan interacted with blunted reward processing to predict increases in depression over time in healthy youth. METHOD: Participants were 245 adolescent girls aged 8-14 years old (Mage = 12.4, s.d. = 1.8) who were evaluated at baseline and two years later. The reward positivity (RewP), an event-related potential measure of reward responsiveness, was assessed at baseline using the doors task. Cumulative lifetime exposure to acute and chronic stressors was assessed two years later using the Stress and Adversity Inventory for Adolescents (Adolescent STRAIN). Finally, depressive symptoms were assessed at both baseline and follow-up using the Children's Depression Inventory. RESULTS: As hypothesized, greater lifetime acute stressor exposure predicted increases in depressive symptoms over two years, but only for youth exhibiting a blunted RewP. This interaction, however, was not found for chronic stressors. CONCLUSIONS: Lifetime acute stressor exposure may be particularly depressogenic for youth exhibiting a blunted RewP. Conversely, a robust RewP may be protective in the presence of greater acute lifetime stressor exposure.

Associations between acute and chronic lifetime stressors and psychosis-risk symptoms in individuals with 22q11.2 copy number variants.

BACKGROUND: The 22q11.2 deletion (22q11Del) is among the strongest known genetic risk factors for psychosis. Stress, a known risk factor for psychosis in the general population, has seldom been studied in 22q11Del. We investigated how lifetime stressors related to symptomatic outcomes in patients with 22q11Del. We also explored this association in individuals with 22q11.2 duplications (22q11Dup), which may be potentially protective against psychosis. METHOD: One hundred individuals (46 with 22q11Del, 30 with 22q11Dup, and 24 healthy controls; Mage = 17.30 years±10.15) were included. Logistic models were used to examine cross-sectional associations between lifetime acute and chronic stressors (severity and count) and the presence (score ⩾3) of positive, negative, and general symptoms, assessed via the Structured Interview for Psychosis-risk Syndromes (SIPS). RESULTS: The 22q11Dup group reported the greatest number and severity of acute lifetime stressors, but did not differ from 22q11Del in chronic stressor count or severity. Lifetime chronic and acute stressors were uniquely associated with positive symptoms in 22q11Del (chronic count: odds ratio [OR] = 2.35, p = 0.02; chronic severity: OR = 1.88, p = 0.03; acute count: OR = 1.78, p = 0.03), but not with negative or general symptoms (ps > 0.05). CONCLUSION: Findings suggest that stress may play a role in psychotic symptoms in 22q1Del, while the 22q11Dup CNV appears protective against psychotic symptoms despite higher rates of stressors. Interventions that mitigate effects of stressors in 22qDel may reduce the odds of psychosis in this group. Prospective longitudinal research is needed to replicate these findings.

Neural correlates underlying preference changes induced by food Go/No-Go training.

Consistently not responding to appetitive foods during food go/no-go training could change individuals' food choices and sometimes even body weight, however, fewer studies have explored the neural pathways underlying the effects of food go/no-go training. In this study, we scanned eighty-six female participants using functional magnetic resonance imaging and investigated the neural bases of preference changes in a binary food choice task following action (e.g., go) or inaction (e.g., no-go) toward distinct foods within a food go/no-go training paradigm. In line with prior behavioral work, we found that participants' food preferences changed as a function of food go/no-go training, with participants choosing more "go" over "no-go" foods for consumption following training. At a neural level, preference changes were inversely associated with frontoparietal and salience network activity when choosing go (vs. no-go) foods. Additionally, task-related functional connectivities from the inferior parietal lobule to the pre-supplementary motor cortex, dorsolateral prefrontal cortex, and dorsal anterior cingulate cortex were related to these preference changes. Together, current work supports that food go/no-go training reliably changes people's preferences. More importantly, our findings suggest that a neural pathway centered on areas traditionally associated with selective attention may interface with prefrontal regions to guide preference changes induced by food go/no-go training, though future studies using other tasks (e.g., passive viewing tasks) are still needed to test this potential neural mechanism.

Forgiveness, rumination, and depression in the United States and Korea: A cross-cultural mediation study.

OBJECTIVE: Although substantial research has separately investigated forgiveness, rumination, and depression in the United States, few studies have investigated all three constructs in the same sample and we know of no studies that have examined how forgiveness, rumination, and depression are interrelated across cultures. METHOD: To address this issue, we conducted a cross-cultural study wherein 204 and 297 healthy young adults from Korea and the United States, respectively, completed the Heartland Forgiveness Scale, Ruminative Response Scale, and Beck Depression Inventory-II. RESULTS: Compared to US participants, Korean participants exhibited more forgiveness, similar levels of rumination, and slightly more depression. Two-group structural equation models revealed that forgiveness was directly related to depressive symptoms, and that forgiveness was indirectly related to depressive symptoms through rumination, in both the United States (proportion mediated = 0.363) and Korea (proportion mediated = 0.394). This indirect association did not differ across cultures. CONCLUSION: Considered together, these results suggest that forgiveness appears to have beneficial effects on depression that are mediated through forgiveness-related reductions in rumination, and, importantly, that these effects are similar across cultures.

Intergenerational transmission of lifetime stressor exposure in adolescent girls at differential maternal risk for depression.

OBJECTIVE: Adolescent girls who grow up with mothers who are depressed are themselves highly vulnerable to developing depression (i.e., "intergenerational transmission of depression"). Stressor exposure is a strong risk factor for depression, and the transmission of depression risk from mothers to daughters is partly due to mothers experiencing more stressors, increasing daughters' stressor burden. However, research in this area has only assessed recent stressors, making the role of cumulative lifetime stressors unclear. METHOD: To address this issue, we recruited 52 dyads of mothers and adolescent daughters, of which 22 daughters were at high maternal risk for depression. Participants completed diagnostic interviews, and daughters additionally self-reported their depressive symptoms. Participants also completed the Stress and Adversity Inventory, a new-generation instrument for assessing cumulative lifetime history of acute and chronic stressors based on the contextual threat approach. We tested moderated mediation models evaluating the conditional indirect effects of mothers' lifetime stressors on high- versus low-risk daughters' depressive symptoms through daughters' lifetime stressors. RESULTS: As hypothesized, mothers of high-risk (but not low-risk) adolescent daughters who reported more lifetime acute stressors had daughters who reported more lifetime acute stressors and current depressive symptoms. Moreover, this finding was driven specifically by mothers' stressors occurring after their daughters' births. There was also tentative evidence that high-risk daughters' lifetime chronic stressors potentiated the impact of daughters' acute stressors on their depressive symptoms. CONCLUSION: These findings provide new insights into how stressful contexts are transmitted intergenerationally.

Stress and memory encoding: What are the roles of the stress-encoding delay and stress relevance?

The effects of acute stress on memory encoding are complex. Recent work has suggested that both the delay between stress and encoding and the relevance of the information learned to the stressor may modulate the effects of stress on memory encoding, but the relative contribution of each of these two factors is unclear. Therefore, in the present study, we manipulated (1) acute stress, (2) the delay between stress and encoding, and (3) the relevance of the information learned to the stressor. The results indicated that stress during encoding led to better memory for study materials that were related to the stressor relative to memory for study materials that were unrelated to the stressor. This effect was numerically reduced for materials that were encoded 40 min after stressor onset (23 min after the stressor had ended) compared with items encoded at the time of the stressor, but this difference was not significant. These results suggest that the relevance of the information learned to the stressor may play a particularly important role in the effects of stress on memory encoding, which has important implications for theories of stress and memory.

Associations between lifetime stress exposure and the error-related negativity (ERN) differ based on stressor characteristics and exposure timing in young adults.

Life stress increases risk for multiple forms of psychopathology, in part by altering neural processes involved in performance monitoring. However, the ways in which these stress-cognition effects are influenced by the specific timing and types of life stressors experienced remains poorly understood. To address this gap, we examined how different social-psychological characteristics and developmental timing of stressors are related to the error-related negativity (ERN), a negative-going deflection in the event-related potential (ERP) waveform that is observed from 0 to 100 ms following error commission. A sample of 203 emerging adults performed an ERN-eliciting arrow flanker task and completed an interview-based measure of lifetime stress exposure. Adjusting for stress severity during other developmental periods, there was a small-to-medium effect of stress on performance monitoring, such that more severe total stress exposure, as well as more severe social-evaluative stress in particular, experienced during early adolescence significantly predicted an enhanced ERN. These results suggest that early adolescence may be a sensitive developmental period during which stress exposure may result in lasting adaptations to neural networks implicated in performance monitoring.

Effects of Early Life Adversity on Pubertal Timing and Tempo in Black and White Girls: The National Growth and Health Study.

OBJECTIVE: Although exposure to abuse in early life predicts earlier pubertal timing, especially for girls, it is unclear if this association generalizes to nonabuse stressors. In addition, the impact of race on the stress-maturation association remains unknown. To address these issues, we examined whether race moderates the effects of early adversity on pubertal timing and tempo using a longitudinal study design. METHODS: In a cohort of 9- and 10-year-old Black and White girls, pubertal (areolar and pubic hair) maturation was assessed annually for 7 years. In adulthood, 368 participants (186 Black, 182 White) reported on abuse and nonabuse stressors they experienced from ages 0 to 12 years. RESULTS: Early life abuse was associated with earlier pubertal timing, as indexed by younger age at menarche (b = -0.22, p = .005, 95% confidence interval [CI] = -0.39 to -0.06) and greater pubic hair development (b = 0.11, p = .003, 95% CI = 0.04 to 0.18), in addition to slower pubertal tempo, as indexed by slower rate of pubic hair (b = -0.03, p < .001, 95% CI = -0.05 to -0.01) and areolar (b = -0.02, p = .02, 95% CI = -0.03 to -0.003) development. These associations were not found for nonabuse adversity. Black girls with early life abuse had greater pubic hair development (b = 0.23, p < .001, 95% CI = 0.12 to 0.35) and were slower in pubic hair tempo (b = -0.07, p < .001, 95% CI = -0.09 to -0.04) than their White counterparts. CONCLUSIONS: Screening for early life abuse may help address health disparities related to earlier pubertal timing.

Markers of a plant-based diet relate to memory and executive function in older adults.

BACKGROUND: Although it is known that plant-based foods are important for physical health, little is known about the relationship between plant-based foods and cognitive health. Emerging evidence suggests that some macronutrients may influence cognition, but it is unclear which domains of cognition are involved; more importantly, it is unknown how a plant-based diet relates to cognition. OBJECTIVE: To examine associations between a plant-based dietary pattern and cognitive functioning. METHODS: Participants were 3,039 older adults who participated in the 2011-2014 waves of the National Health and Nutrition Examination Survey (NHANES). The present cross-sectional study used data on macronutrient intake from 24-hour dietary interviews, as well as performance on tests of long-term memory and executive function (i.e., delayed word recall, digit symbol substitution test, and animal fluency). Principal component analysis was used to extract a dietary pattern consistent with a plant-based diet. RESULTS: Greater adherence to a dietary pattern consistent with a plant-based diet was related to better performance on all cognitive tasks. Secondary analyses indicated that the associations between a plant-based dietary pattern and executive function accounted for the association between a plant-based dietary pattern and memory. Furthermore, this same plant-based dietary pattern was associated with reduced baseline inflammation in a separate dataset. CONCLUSIONS: Experimental manipulations are needed to determine the potential causal relations of these associations, but these results suggest that a plant-based diet relates to better cognition, especially through improved executive control. Future work should also attempt to extend these results by examining potential mechanisms underlying these associations, such as reduced inflammation.

Hypothalamic-Pituitary-Adrenal Axis Activity in Childhood Predicts Emotional Memory Effects and Related Neural Circuitry in Adolescent Girls.

Negative emotional experiences can be more difficult to forget than neutral ones, a phenomenon termed the "emotional memory effect." Individual differences in the strength of the emotional memory effect are associated with emotional health. Thus, understanding the neurobiological underpinnings of the emotional memory effect has important implications, especially for individuals at risk for emotional health problems. Although the neural basis of emotional memory effects has been relatively well defined, less is known about how hormonal factors that can modulate emotional memory, such as glucocorticoids, relate to that neural basis. Importantly, probing the role of glucocorticoids in the stress- and emotion-sensitive period of late childhood to adolescence could provide actionable points of intervention. We addressed this gap by testing whether hypothalamic-pituitary-adrenal (HPA) axis activity during a parent-child conflict task at 11 years of age predicted emotional memory and its primary neural circuitry (i.e., amygdala-hippocampus functional connectivity) at 16 years of age in a longitudinal study of 147 girls (104 with complete data). Results showed that lower HPA axis activity predicted stronger emotional memory effects, r(124) = -.236, p < .01, and higher emotional memory-related functional connectivity between the right hippocampus and the right amygdala, ß = -.385, p < .001. These findings suggest that late childhood HPA axis activity may modulate the neural circuitry of emotional memory effects in adolescence, which may confer a potential risk trajectory for emotional health among girls.

The association between obesity and lower working memory is mediated by inflammation: Findings from a nationally representative dataset of U.S. adults.

Obesity is often accompanied by lower working memory (e.g., a lower ability to keep goal-relevant information in mind) relative to healthy weight individuals. Understanding this relative working memory impairment has important clinical implications, as working memory is thought to facilitate adherence to weight management programs. Theoretical models of obesity, self-regulation, and inflammation suggest that inflammation plays a role in obesity-related working memory impairments, but to date no study has tested this prediction. Therefore, the current study examined whether inflammation statistically mediated the relationship between obesity and working memory in a nationally representative dataset of U.S. adults from Wave IV of The National Longitudinal Study of Adolescent to Adult Health (N = 11,546, age range 25-34). Inflammation was quantified via C-reactive protein (CRP) level, and working memory was assessed using a modified digit span backward task. As expected, cross-sectional analyses showed that a body mass index (BMI) indicative of obesity-as well as greater BMI when BMI was analyzed continuously-and greater CRP were each related to lower working memory. Critically, we found that CRP levels statistically mediated the relationships between obesity/greater BMI and working memory, with CRP accounting for 44.1% of the variance explained in working memory by BMI. Moreover, these findings held both with and without controlling for relevant covariates, including demographic characteristics (e.g., age), socioeconomic status, and behavioral factors (e.g., smoking). Our results therefore point to inflammation as playing an important role in the relationship between obesity and working memory, and suggest that interventions aimed at reducing inflammation may help lessen the cognitive burden of obesity.

Deconstructing the effects of concentration meditation practice on interference control: The roles of controlled attention and inflammatory activity.

Prior work has linked meditation practice to improvements in interference control. However, the mechanisms underlying these improvements are relatively unknown. In the context of meditation training, improvements in interference control could result eitherfrom increases in controlled attention to goal-relevant stimuli, or from reductions in automatic capture by goal-irrelevant stimuli. Moreover, few studies have linked training-related changes in attention to physiological processes, such as inflammatory activity, that are thought to influence cognitive function. This study addresses these gaps by examining associations between cognitive performance and cytokines in the context of an intensive meditation retreat. Participants were randomly assigned to complete 3 months of meditation training first, or to serve as waitlist controls. The waitlist-control participants then later completed a separate 3-month training intervention. We assessed participants' interference control with a flanker task and used computational modeling to derive component processes of controlled and automatic attention. We also collected blood samples at the beginning, middle, and end of training to quantify changes in cytokine activity. Participants who completed training evidenced better controlled attention than waitlist controls during the first retreat intervention, and controls showed significant improvements in controlled attention when they completed their own, second retreat. Importantly, inflammatory activity was inversely associated with controlled attention during both interventions. Our results suggest that practice of concentration meditation influences interference control by enhancing controlled attention to goal-relevant task elements, and that inflammatory activity relates to individual differences in controlled attention.

Using acute stress to improve episodic memory: The critical role of contextual binding.

Previous research has shown that encountering a brief stressor shortly after learning can be beneficial for memory. Recent studies, however, have shown that post-encoding stress does not benefit all recently encoded memories, and an adequate theoretical account of these effects remains elusive. The current study tested a contextual binding account of post encoding stress by examining the effect of varying the context in which the stressor was experienced. Participants encoded a mixture of negative and neutral images, immediately followed by a stressor (i.e., socially evaluated cold pressor) or a non-stress control task. Half of the participants received the stress/control manipulation in the same context as the study materials and half were moved to another context (i.e., a different room with a different experimenter). Two days later all participants returned to the original study room and received a recognition memory test. The results indicated that stress increased recognition memory only when the stressor occurred in the same context as the study materials, whereas stress did not benefit memory if the stressor occurred in a different context. Moreover, stress related increases in salivary cortisol were related to increases in memory when the stressor occurred in the same context as the study materials but not when the context changed. Similar effects were observed for negative and neutral materials and for males and females. These results are consistent with a contextual binding account and suggest that stress acts on memory by enhancing the encoding of the ongoing context of the stressor which benefits memory for the immediately preceding events that share the same context.

The short-term reliability and long-term stability of salivary immune markers.

Salivary markers of immune function are increasingly commonly used in studies of human health. Yet, few studies have examined the short-term or long-term reliability or stability of these biomarkers, making their measurement properties unclear. We addressed this issue in the present study by collecting two saliva samples, two hours apart, from 426 adolescent girls during a baseline laboratory visit. Then, eighteen months later, we collected the same samples again from a subset of these participants (n = 113). The correlations between the two samples collected at each session were generally high (mean r = 0.67). In contrast, although single saliva samples were only weakly correlated across 18 month (mean rs = 0.18), averaging the two quantifications within a session considerably improved the reliability (mean r = 0.27). In short, salivary immune markers exhibited strong short-term test-retest correlations, and averaging across multiple assessments notably improved long-term test-retest correlations. Additional research is needed to establish the health relevance and mechanisms underlying these potentially useful, non-invasive biomarkers.

Determining the biological associates of acute cold pressor post-encoding stress effects on human memory: The role of salivary interleukin-1ß.

Stress generally hurts many aspects of memory, but an interesting finding to emerge from the stress and memory literature is that stress that occurs shortly after learning (i.e., post-encoding stress) usually benefits memory. Although this effect is well established, the biological mechanisms underpinning this effect are not-especially in humans. We addressed this gap in the present study by collecting saliva samples from 80 participants who were randomized to a post-encoding stress (i.e., cold pressor for 3 min) or control task (i.e., warm water for 3 min) and 48 h later completed a recognition memory task. Saliva was collected both prior to and 15 min after the offset of (18 min after the onset of) the stress/control manipulation. Drawing on animal and human work, we examined how five stress-responsive biomarkers-cortisol, salivary α-amylase, progesterone, estradiol, and the proinflammatory cytokine interleukin (IL)-1ß, all assessed in saliva-related to the effects of stress on memory. We found that stress enhanced recollection of negative images and that these effects were selectively related to salivary IL-1ß. Moreover, we found that the beneficial effects of stress on memory were statistically mediated by salivary IL-1ß. We found no robust associations-either linear or quadratic-between memory and any other biomarker, nor did we find significant interactions between biomarkers in predicting memory. These results suggest that immune system activity indexed by salivary IL-1ß may play an important role in contributing to post-encoding stress effects on human memory.