Project by Kelly Yang

Hypothesis Elevated cortisol levels will enhance the ability of adolescent men to remember emotionally agitating image slides through the administration of cold pressor stress (CPS).

Review of Literature Enhanced human memory consolidation with post- learning stress: Interaction with the degree of arousal at encodingL Cahill, L Gorski, K Le - Learning & Memory, learnmem.cshlp.org Enhanced human memory consolidation with post- learning stress: Interaction with the degree of arousal at encoding Working memory performance after acute exposure to the cold pressor stress in healthy volunteersR Duncko, L Johnson, K Merikangas… - Neurobiology of learning …, 2009 – ElsevierWorking memory performance after acute exposure to the cold pressor stress in healthy volunteers

Abstract Evidence suggests that endogenous stress hormones such as epinephrine and corticosterone can enhance memory consolidation in humans. Post-exposure stress hormone activation is known to modulate memory for emotionally stressful events, which leads to the disorder known as PTSD, or Post- Traumatic Stress Disorder. The affects of stress hormone activation may vary between men and women, causing a certain sex to be more susceptible to memory consolidation. This project investigates if elevated cortisol levels will enhance the ability of adolescent men to remember emotionally agitating image slides through the administration of cold pressor stress (CPS). The subjects to whom CPS was administered showed no statistical difference in their ability to recall details about the slides viewed, and showed minimal correlation between the changes in their cortisol levels and their recall of slides.

Background Women are more likely than men to develop PTSD. About 10% of women develop PTSD compared with 5% of men Decreased cortisol levels at the time of a traumatic event could prolong the availability of norepinephrine to synapses in both the periphery and the brain, which in turn might affect the consolidation of the memory of the incident. Postmenopausal women are more susceptible to memory impairing effects of elevated cortisol levels than elderly men CPS elevated salivary cortisol in both sexes but enhanced memory only in male subjects in “Glucocorticoid Release and Memory Consolidation in Men & Women”

CPS significantly enhanced memory for slides defined by the subjects as relatively emotionally arousing - Larry Cahill, Lukasz Gorski, and Kathryn Le, “Enhanced Human Memory Consolidation With Post-Learning Stress: Interaction With the Degree of Arousal at Encoding” Exposure to stress showed no increase in salivary cortisol in “Working Memory Performance After Acute Exposure to the Cold Pressor Stress in Healthy Volunteers” Cortisol increase in response to the stress was negatively correlated with the memory performance within the stressed group (subjects w. larger cortisol response recalled less words than subjects w. small cortisol increase) Glucocorticoid release and memory consolidation in men and women Glucocorticoid release and memory consolidation in men and women JM Andreano JM Andreano, L Cahill - Psychological Science, pss.sagepub.com

Materials 19 healthy subjects, about the same number for each gender Written informed consent/rules - NOT allowed to discuss Data sheet to record discomfort rate/names of slides/subject information 21 slides & computer to show slides Low to moderate arousal quality Initial slide must be neutral, 15 sec. for each slide, no blank screen between slides Ice water & tray (0-3 degrees Celsius), ice Warm water & tray (37-50 degrees) Salivary cortisol assay kit – 2 samples each, then duplicate Refrigerator to preserve samples Thermometer to monitor temperature of water

Method Pre-test: 1) Give consent forms/information to subjects Test: 1) Take initial saliva sample 2) Subject sits in chair at a consistent distance from the computer screen 3) Dim lights and play slides, every five seconds into the slide, subject needs to name slide with word or short phrase – record names 4) Subject places hand in either warm or cold water. If warm water, hold for 3 minutes. If cold water, hold for as long as possible and not more than 3 minutes. 5) Rate discomfort from ) After subject takes hand out of water, take final saliva sample Post-test (after all saliva samples are taken): 1) Assay saliva samples using the Salivary Cortisol Assay Kit from Salimetrics Post-test (one week later): 1) Subjects return to take free-recall test of memory of slides viewed already - given as much time as needed, prompt to write more when they are about to finish 2) View slides again & rate each from 1-9 with 1 = relaxing, 5 = neutral and 9 = agitating

Results Note: Data collected from two subjects was eliminated from the study because the second saliva samples were too small to assay accurately Subject Number Discomfort During Submersion % Change

SubjectGender Water Temperature (degrees Celcius) Cortisol Before (Avg. ug/dL) Cortisol After (Avg. ug/dL) % Change in Cortisol Level Discomfort during submersion (0-10) Points Awarded for Slides/Details 3m m m f f m m m m m m m f m m m m

Discussion After finding the linear regression of the correlation between the number of details remembered and the percent elevation of cortisol levels, it was discovered that there was too little evidence to reject the null hypothesis: that the number of details remembered is the same between the CPS and control groups. A two-sample T test was performed to test the correlation between percent change in cortisol levels and temperature, and once again the P value (0.31) showed that there was not enough evidence to reject the null hypothesis. The Cold Pressor Stress proved ineffective in elevating cortisol levels; however, cortisol levels may have been elevated a few minutes after the CPS was administered, in which case the second cortisol samples were taken prematurely. In a revised experiment, a larger group of subjects would be required to better test the hypothesis.

Conclusion The Cold Pressor Stress proved ineffective in elevating the cortisol levels. The number of details remembered is the same between the CPS and control groups.

Acknowledgements & Bibliography The researcher would like to acknowledge: Dr. Larry Cahill Dr. Bing Chen Ms. Michelle Maxson Bibliography n_is_ptsd.html n_is_ptsd.html oendocrinology.pdf oendocrinology.pdf ndreano_Sleep_glucocorticoid.pdf ndreano_Sleep_glucocorticoid.pdf