Exploring High-throughput Paradigms For Inducing Acute Psychological Stress In The Laboratory: The N-Back Stress Test And The Trier Social Stress Tes

Background Large sample size is essential to gain statistical power for studying the genetics and epigenetics of acute stress responses.However,there is still a lack of a high-throughput phenotyping method for stress.The Trier Social Stress Test(TSST)is a widely used laboratory acute stress test,and generally takes salivary cortisol as a biomarker of stress.How large a sample of TSST study is needed to produce a stable salivary cortisol response remains elusive.The effects of speech topic and interaction between sex and speech topic on salivary cortisol responses in TSST remain unknown.Moreover,TSST faces two major problems: the low throughput of the single-subject method and the interaction between audience and subjects increase study heterogeneity.Thus,we conducted two studies.We evaluated the effects of the TSST studies and the sample size required to induce a robust salivary cortisol response in study 1.Based on the results of study 1,study 2 developed a new alternative procedure for highthroughput phenotyping methods for acute psychological stress.Methods In study 1,we performed a meta-analysis to evaluate the effects of speech topic,sex,and the interaction between sex and speech topic in the TSST using salivary cortisol reactivity as an objective measure.We collected TSST research articles in Web of Science,Pub Med,Psyc Net,and CNKI.A total of 65 articles involving 76sub-studies were included in this meta-analysis,with a total of 5171 participants.In study 2,we developed a new substitute procedure N-Back Stress Test(NBST)to induce laboratory acute psychological stress responses.We evaluate the performance of NBST by comparing it with a modified electronic Trier Social Stress Test(e-TSST).We recruited 166 college students into the study.Additional 13 subjects were recruited for the control group.All participants were measured for Systolic Blood Pressure(SBP),Diastolic Blood Pressure(DBP),Heart Rate(HR),and subjective Visual Analog Scale(VAS)four times during the tasks.Results The results of study 1 showed that the average effect size(i.e.,Cohen’s d)of salivary cortisol reactivity was 0.93.The small studies produced larger variations in the reported effect sizes than the large-sample studies.The statistical power estimate and empirical data showed that a sample size of 40 was necessary to provide sufficient statistical power to detect salivary cortisol response in TSST.Speech topic,sex,and sex-speech topic interaction could predict salivary cortisol responses,but sex was the only significant contributing factor in the regression model.Salivary cortisol responses in males were significantly higher than in females.Further,significant differences between males and females were detected at baseline and peak.The results of study 2 showed that both the NBST and e-TSST induced robust stress responses in SBP,DBP,HR,and VAS.There were significant correlations between SBP,HR,and VAS responses induced by NBST and e-TSST,although NBST induced lower stress responses than e-TSST for the measures of SBP and VAS.NBST had significant correlations with e-TSST in SBP,HR,and VAS.NBST had no significant differences between test and retest in all four stress markers,but e-TSST had significantly reduced responses for SBP and VAS in the second test.Conclusions In study 1:(1)The TSST effectively induces stress response as measured by salivary cortisol change.(2)Forty samples is the minimum sample size for detecting the robust salivary cortisol responses.(3)Males have stronger salivary cortisol reactivity than females in TSST.(4)Speech topics and interaction between sex and speech topic did not significantly contribute to variations in the salivary cortisol responses.In study 2:(1)NBST could induce robust psychological stress with comparable effects with e-TSST.(2)NBST has better test-retest reliability and consistency between the two repeated tests than e-TSST.(3)NBST that can accommodate multiple subjects simultaneously is a high-throughput method of inducing acute psychological stress,with potential of good generalizability.