Meditation, Stress and Working Memory. jeremiah Slutsky. Northeastern University

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1 Meditation, Stress and Working Memory 1 Meditation, Stress and Working Memory jeremiah Slutsky Northeastern University

2 Meditation, Stress and Working Memory 2 Abstract As meditation has grown increasingly popular as a practice to reduce stress and calm the mind, researchers are uncovering the scientific benefits of this age old tradition. The goal of this study was to investigate some of the cognitive benefits of meditation, specifically in regards to working memory. Previous research shows acute stress can produce an impairment on working memory. Prior research on various meditation programs show an ability for meditation to reduce stress. This 8- week study involved 34 young adults from the Boston area who were placed into a compassion meditation, mindfulness meditation, or well-being discussion class. The hypothesis predicted that the lasting effects of meditation will attenuate the cognitive effects of stress. There was no conclusive evidence linking reduced stress in the meditation groups to improved working memory as compared to the wellbeing discussion class. Keywords: Meditation, stress, working memory Introduction Meditation is a well-being practice that has existed on this planet for hundreds of years. Although it's efficacy has been viewed with certainty in eastern traditions, western society is still wary of implementing the practice in mainstream physical and mental health. The issue lies in that western science is slowly uncovering the vast array of medicinal benefits that stem from meditation. Among the conclusive evidence, typically seen through moderately intensive eight-week stress reduction courses, meditation has provided evidence to change brain structure, regulate emotion, treat illness, and improve behavioral choices. Although

3 Meditation, Stress and Working Memory 3 there is prominent and conclusive evidence that meditation reduces stress and improves cognitive functioning, there is still more to uncover about the potential benefits of this ancient practice (Lutz et a!., 2008). This thesis will examine whether meditation could potentially attenuate the cognitive effects of stress as well as aid in regulating emotion. Before discussing the ways in which meditation can intervene with stress, it is useful to provide an overview regarding the nature of stress itself and the underlying biological processes involved. On a psychological level, stress is defined as a feeling of strain and pressure. On a physiological level, it is represented through a variety of physical responses that occur as a direct effect of a stressor causing an upset in the homeostasis of the body (Schoofs et a!., 2008). When an event that is interpreted as stressful occurs, the hypothalamic pituitary adrenal (HPA) axis is triggered by neurons in the hypothalamus releasing the corticotropinreleasing hormone (CRH). The release of CRH triggers the secretion of another hormone called adrenocorticotropin hormone (ACTH) from the pituitary gland. ACTH travels in the blood and arrives at the adrenal gland, which triggers the release of glucocorticoids (called cortisol in humans) and catecholamines (adrenaline and noradrenaline). The release of these two stress hormones cause a variety of effects to the body, but among the most notable and relevant to this paper, causes changes to the brain. The regions that are specifically affected in the brain are the hippocampus, amygdala, and frontal lobe regions, - all of which are areas that are important for memory (Lupien et a!., 2007).

4 Meditation, Stress and Working Memory 4 The research on stress and memory can be confusing because there are circumstances in which stress can enhance as well as diminish memory. One study shows that participants who were induced with fear and had increased cortisol levels presented better consolidation of emotionally relevant memory, processed in the amygdala (Zorawski, 2006). Furthermore, another study that tested the impact of acute increase in glucocorticoids on memory processing provides evidence that acute stress administered just before the acquisition of a word list can impair retrieval, in other words, inhibiting memory processed by the hippocampus (Roozendaal et a!., 2006). Working memory is defined as the process of temporarily maintaining, updating, and manipulating information (Schoofs et a!., 2008). A study by Lupien et a!. (2007) involved an infusion of 100mm of glucorcoticoids to 40 young subjects for 100 minutes while declarative and working memory was tested. Results indicate that working memory is more sensitive than declarative memory on young individuals exposed to an acute elevation of glucocorticoids. This study supports the notion that glucocorticoids, a stress chemical, has a significant impact on frontal lobe functioning, specifically regarding working memory. In the current study, I examine the possible ability of meditation to diminish the negative effects of stress on working memory. Much of the prior literature on meditation usually involves mindfulness-based programs. Mindfulness-Based Stress Reduction (MBSR) is a standardized meditation program created by jon Kabat-Zinn (1979) to integrate Buddhist mindfulness meditation with clinical practice. Initially developed as a group-based program to alleviate chronic pain, it

5 Meditation, Stress and Working Memory 5 has been shown to affect various other mental and physical disorders with good efficacy over the past two decades. MBSR involves three different techniques: a body-scan, sitting mindfulness meditation, and Hatha yoga practice. Furthermore, most programs also involve 45 minutes per day of homework for 6 days a week during the 8 weeks. A meta-analysis review published by Chiesa et a!. (2009) reported that MBSR provided a significant effect on reduction of stress levels in comparison with no treatment in healthy subjects. In the present study, participants completed a meditation program containing similar elements to MBSR (see Methods section for specific details). The other meditation group used in this study practiced compassion meditation over the 8-week course. Prior literature shows that compassion meditation practice can increase self-compassion, which has been shown to reduce perceived stress, burnout, depression, and anxiety (Lutz et a!., 2008). Compassion meditation is described as an "unconditional readiness and availability to help living beings (Lutz et a!., 2008). Instead of concentrating on particular objects or images, compassion meditation focuses on spreading love or compassion to particular persons or groups of beings. Pace et a!. conducted a study on 61 healthy students at Emory University who were randomly assigned to either a 6-week compassion meditation training or a health discussion group. The compassion meditation program was a 50-minute class twice a week that combined teaching and discussion with an average of 20 minutes of meditation practice. Participants were also given an "at-home" meditation CD to guide individual practice. Results indicate that those who had increased at-home meditation practice were correlated with lower scores

6 Meditation, Stress and Working Memory 6 on the Trier Social Stress Test (TSST), a reliable test that triggers the HPA, and decreased levels of cortisol as triggered by the TSST. A study by jha et a!. (2010) provides evidence of mindfulness training having the ability to protect working memory from stress. jha's study involved 17 male U.S. Marine Corps reservists undergoing a Mindfulness-Based Mind Fitness Training, which is similar to MBSR in that it involves 24 hours of class instruction over 8 weeks, and concluding with a stress-inducing math task and a working memory task letter task. My study continues where jha's study left off by measuring if compassion meditation may also provide an effect on reducing the negative effects of stress on working memory. In my study, I am measuring working memory through a task called the digit span task. This task will be used for this proposed study as it has been observed in other studies where performance has been impaired following induced stress in participants (e.g., cortisol administration, Wolf et a!., 2001a; psychosocial stress exposure, Elzinga & Roelofs, 2005). My prediction is that those who have participated in the compassion meditation and mindfulness meditation courses will get higher digit span scores than those in the nonmeditation group after undergoing the stress-induction task. Another measure examined in this study involves the differences between the meditators and non-meditators with respect to emotion regulation. The Emotion Regulation Questionnaire (ERQ) is a reliable ten-item questionnaire that measures one's emotional response on a day-to-day basis (Gross et a!., 2003). Two strategies measured in the ERQ are cognitive reappraisal and expressive suppression. Cognitive reappraisal is a form of construing a potentially emotion -eliciting-

7 Meditation, Stress and Working Memory 7 situation to manipulate its emotional impact. Expressive suppression responds to emotional stimuli by inhibiting ongoing emotion-expressive behavior. An example of cognitive reappraisal would be if one viewed a job interview as an opportunity to gage whether they would like the job, rather than as a test of one's worth for the position. An example of expressive suppression would be to keep a straight face during a game of poker, even if one is having a great or terrible hand. Those that use expressive suppression as a main coping strategy to regulate their emotions have been linked with increased and prolonged distress (Gross et al., 2003). Although there is not yet any research to support either of these notions, by the nature of the definitions, one would expect those that practice compassion meditation not to utilize expressive suppression, and those that practice mindfulness meditation to indeed utilize cognitive reappraisal as an emotion regulation strategy. Compassion meditation teaches practitioners to spread love and kindness to others as well as using compassion to relieve other's suffering, the opposite of expressive suppression, which would be to inhibit these emotionexpressive behaviors. When one practices mindfulness meditation, they are subsequently practicing regulating attention, orienting to immediate experience, awareness of experience, and an attitude of acceptance or non-judgment towards experience, the last of which draws parallels to cognitive reappraisal. I predict that participants who experience less stress, in the form of using cognitive reappraisal to better regulate their emotions, will perform better on the subsequent digit span task Methods

8 Meditation, Stress and Working Memory 8 Participants A group of 34 young adults from the Boston area participated in the study, predominately undergraduate students at Northeastern University. Of the sample of 34, there were 26 females and 8 males. The range of age was from 18 to 26 years old with a mean of 20. All participants reported that they had either little to no previous experience with meditation. There were 9 participants placed in the compassion meditation group, 15 participants in the mindfulness meditation group, and 10 participants in the well-being group. Procedures After an initial lab visit in which physiological measurements (unrelated to the goals of the present analyses) were taken on participants during a stressinducing mental math task, participants were randomly assigned to one of three courses that contain a particular focus on well-being: a mindfulness meditation, compassion meditation, or a healthy lifestyle class. The meditation classes were held in a professional meeting room and were led by an expert meditation instructor with more than 30 years of meditation experience. The classes featured a secular format including 30 minutes of instruction/discussion and 30 minutes of practice. The classes were held once a week for 8 weeks. The participants also received 20 minutes of audio-guided meditations to complete outside of class. The participants were compensated up to $80 for the completion of their participation. After the eight-week class, participants returned to the lab for further physiological measurements, stress inducing tasks, and completed surveys including the emotion

9 Meditation, Stress and Working Memory 9 regular questionnaire. At the very end of the lab session, the same participants complete the digit span task. Measures In the digit span task, participants must repeat a series of digits. The length of the series of digits increases up to a maximum of nine digits. The participant gets two trials for each series of length, but the task is terminated after a subject fails to accurately and completely repeat both digit series of a particular length (Weschler, 1987). The Emotion Regulation Questionnaire (ERQ) is a computer-based survey consisting of ten questions. The participants take the survey in two trials - before and after the 8-week course. The ERQ is a reliable questionnaire that is able to measure certain strategies people use to regulate their emotions during day-to-day experiences (Gross et al., 2003). This study specifically investigates the ERQ scores in regards to cognitive reappraisal and expressive suppression. Results The results show no significant effect of the meditation groups on the digit span scores. The 9 participants in the compassion meditation group had an average digit-span score (DSS) of 6.1 (SD=.93); the 15 participants of the mindfulness meditation group had a mean DSS of 5.8 (SD=1.1); the 10 participants in the wellbeing group had a mean DSS of 6.1 and (SD=1.1). A one way analysis of variance showed the effect of meditation was insignificant, F(2, 34) =.33, p=.712. The results also show no significant effect of the meditation groups on the cognitive reappraisal and expressive suppression scores. The 9 participants in the

10 Meditation, Stress and Working Memory 10 compassion meditation group had an average reappraisal score of 5.14 (SD=.66) and an average suppression score of 3.48 (SD=1. 2) on the first trial. On the second trial, the compassion meditation group had an average reappraisal score of 5.01 (SD1.14) and an average suppression score of 3.34 (SD=1.12). The "D" (t2-t1) variable for the 11 participants in the compassion meditation group (sample sizes are different for the ERQ scores because some participants completed the ERQ but requested to opt out of the digit span task) for the reappraisal scores has a mean of -.09 (SD=.78) and a mean of -.18 (SD=1.25) for the suppression scores. The 15 participants in the mindfulness meditation group had an average reappraisal score of 4.54 (SD=1.11) and an average suppression score of 3.59 (SD=1.35). On the second trial, the mindfulness meditation group had an average reappraisal score of 4.92 (SD=.93) and an average suppression score of 3.42 (SD=1.23). The "D" variable mean is -.02 (SD=1.35) for the reappraisal scores and -.17 (SD=-.12) for the suppression scores. The 12 participants in the well-being group had an average reappraisal score of 4.79 (SD=.SO) and an average suppression score of 3.81 (SD=1.23). On the second trial, the well-being group had an average reappraisal score of 5.04 (SD=.66) and an average suppression score of 3.25 (SD=1.50). The "D" variable mean is.25 (SD=.66) for the reappraisal scores and -.56 (SD=1.33) for the suppression scores. A one way analysis of variance showed the effect of meditation was insignificant on the reappraisal scores was insignificant, F(23,14) =.89, p=.61 and insignificant for the suppression scores F(15,22) =.99, p=.49. Discussion

11 Meditation, Stress and Working Memory 11 Although the hypothesis was not supported by the results of the study, it is still not fair to write off that there is no correlation between meditation, the reduced effects of stress on working memory, and cognitive reappraisal in emotion regulation. There are several limitations in the study that may have impeded favorable results for meditation. The first limitation is that the participants may have suffered from fatigue. The participants previously had undergone a 1 hour and 15 minute lab session where they endured a stress-inducing task for 10 minutes. Perhaps a greater number of participants who had less fatigue and completed a larger amount of working memory trials would produce results that were expected in the hypothesis. The second limitation is that the digit span task in itself may have been stress-inducing. Having a human experimenter conducting the digit span task may have provoked stress due to the effects of social evaluation. A computer-based digit span task could alleviate this effect. Another limitation is that there was too much time in between the stress induced task and the digit span task. Participants filled out questionnaires for roughly five minutes and were debriefed for another five to ten minutes before they were administered the digit span task. Not only did the time in between the stress task and the digit span task potentially bring the participants back to baseline, but the time of day may have affected the levels of cortisol in their body. Research shows that the morning time is when stress hormones are most reactive, and there was no control for time of day in this study (Roozendaal et a!., 2006). Lastly, there was no before and after measurements. Perhaps the participants in the meditation groups improved between trials in regards to before and after their meditation program, which would confirm the

12 Meditation, Stress and Working Memory 12 hypothesis that meditation intervenes with the negative effects of stress on working memory. Besides the research done by jha, there is not much literature on how meditation intervenes with the negative effects of stress on working memory. Even though this study did not support the hypothesis, and jha's study did indeed find conclusive results, there is not enough evidence to deduce that meditation is or isn't an effective intervention. This study calls for more conclusive evidence on the matter.

13 Meditation, Stress and Working Memory 13 References Jha, A, Stanley, E., & Kiyonaga, A (2010). Examining the protective effects of mindfulness training on working memory capacity and affective experience. Emotion, 1 0(1 ), Retrieved from http: // content/uploads/jha stanley etal emotion 2010.pdf. Lupien, S.J., Maheu, F., Tu, M., Fiocco, A, Schramek, T.E., The effects of stress and stress hormones on human cognition: implications for the field of brain and cognition. Brain Cogn. 65, Lutz, A L. (2008). Regulation of the neural circuitry of emotion by compassion meditation: Effects of meditative expertise. PLoS ONE, 3 (3). Gross, James J.; John, Oliver P., Individual differences in two emotion regulation processes: Implications for affect, relationships, and well-being. journal of Personality and Social Psychology, 85, Roozendaal B., Okuda, S., de Quervain, D.J., McGaugh, J.L., Glucocorticoids interact with emotion-induced noradgrenergic activation in influencing different memory functions. Neuroscience 138, Schoofs, D., Preub, D., Wolf, 0., Psychosocial stress induces working memory impairments in an n-back paradigm. Psychoneuroendocrinology. (33) Wechsler, D., WMS-R Manual: Wechsler Memory Scale-Revised. Harcourt Brace Jovanovich, Inc., The Psychological Corporation, New York

14 Meditation, Stress and Working Memory 14 Wolf, O.T., Convit, A., McHugh, P.F., Kandil, E., Thorn, E.L., De Santi, S., McEwen, B.S., de Leon, M.j., 2001a. Cortisol differentially affects memory in young and elderly men. Behav. Neurosci. 115, Wolf, O.T., Effects of stress hormones on the structure and function of the human brain. Expert Rev. Endocrinol. Metab.1,