The Effects of Spearmint Chewing Gum on Cognition and Electroencephalogram

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1 The Effects of Spearmint Chewing Gum on Cognition and Electroencephalogram Kristen Campbell, Vanessa Malochleb, Maia Assaf, Wally Moreno, Donald Jones Faculty Sponsor: Julius Militante Department of Biology; University of Michigan-Flint Abstract The purpose of this project was to test for any changes in brain waves and cognition as affected by chewing Trident spearmint gum, which is associated with therapeutic and aroma therapeutic claims. These changes were measured using an Electroencephalogram (EEG), on a Student Biopac Laboratory System, and an online Stroop Test. We have found that chewing spearmint gum 5 minutes prior to testing does not have a significant effect on cognition and does not have a significant effect on alpha, beta, delta, or theta waves. The results of this study are supported by several other published studies. It is possible that 5 minutes is not adequate time for the benefits of increased blood flow and increased insulin release to take effect. More research is needed to confirm these hypotheses. This project was conducted as an required experimental project at the University of Michigan-Flint for a Mammalian Physiology course. Introduction There have been numerous studies done to test the effects of chewing gum on cognition and to test the effects as measured on an Electroencephalogram (EEG). It is thought that the increase in cognition while chewing gum may be due to an increase in cerebral blood flow to the frontal/temporal brain regions, increase the amount of insulin released, or create a context dependent effect (Baker et al, 2004)(Tusha & Simpson, 2010). Mastication has been shown to increase cerebral blood flow using Positron Emission Topography (PET) and Magnetic Resonance Imaging (MRI) (Momose et al, 1997). Using Transcranial Doppler ultrasound, Hawegawa et al (2007), also found that middle cerebral artery blood flow velocity increases during chewing gum. Increased blood flow to certain areas of the brain may, in part, be the reason for increased cognition and changes in brain wave activity. Neurons in the brain communicate via electrical impulses through synapses of neurons. These electrical impulses result in a change in voltage that can be summated and measured by electrodes on the surface of the skin. EEG s are a useful diagnostic test for epilepsy or sleep disorders. A Stroop test is a psychological test that measures cognition and the ability to focus attention on a task. The idea of the Stroop test is that it takes longer to identify a color by its name when the name is not denoted by the color. This is thought to increase the time it takes to decide the color and increases the risk for mistake. A Stroop test measures 2 different times: normal and interference. Normal time is the time it takes a person to identify a color when the name is denoted by the color. For example, the word is red and the color font is red. Interference time is the time it takes a person to identify a color when the name is not denoted by its actual color. For example, the word is red but the actual font color is orange. There have been studies implying there are no cognitive improvements associated with chewing gum (Onyper et al, 2011) but these studies have been done with subjects chewing gum during testing which may have an effect on cognition. It is possible there is an initial period of time where the brain is distracted by the act of chewing gum. It is also possible these studies did not test cognition long enough to witness the full benefits. Onyper et al (2010) tested cognition as a function of time and found initially

2 chewing gum had negative effects on cognition but after minutes chewing gum was more beneficial for cognition and focus than those not chewing gum. Tucha & Simpson (2010) also found that chewing gum while learning enhances recall 24 hours later more significantly than for those who did not chew gum while learning thought to be due to a context dependent learning situation. EEG s have shown an increase in alpha waves at occipital lobe region 1 (O1) and a decrease in beta, theta, and delta waves at multiple regions in the brain after chewing gum with sucrose and flavored aromatic oil (Morinushi et al, 2000)(Mosumoto et al 1999). Alpha waves may indicate a more relaxed concentration, as these are the high amplitude, low frequency waves that occur when a person is awake but relaxed. Beta waves are the opposite, low amplitude, high frequency waves that occur when a person is awake and alert. It is currently unclear as to why these brain waves are affected while chewing gum. Chewing gum 5 minutes prior to cognitive testing has been significantly found to improve certain areas of cognitive functioning such as: recall (under full attention conditions), recall (under divided attention), working memory, and perceptual speed of processing (Onyper et al, 2011). It was also found the positive effects of chewing gum on cognition decrease as task load increase. Some students were given Wrigley s Spearmint gum with sugar, Wrigley s Spearmint gum sugar-free, and a control group of students that were given no gum. The rate of mastication was controlled at one bite per second for 5 minutes (including the control group). Prior to each of the five cognitive tasks to be performed, students were given time to become familiar with the requirements for each task. Chewing gum can enhance learning and later recall (Baker, 2004)(Tucha, 2010). It has been found that chewing gum may have a context dependent effect on learning and recall. There was a significant difference for the groups that were chewing gum while learning as compared to groups not chewing gum while learning. It was also found that sucking on spearmint gum had a significant increase in learning and later recall as compared to no sucking or chewing on gum while learning. This study may raise questions as to whether the enhanced learning effect is due to mastication or a response to flavor. Due to these findings, our experiment is designed to test the effect of chewing spearmint gum after 5 minutes on brain waves as measured by an EEG and on cognition using a Stroop test. This project was conducted at the University of Michigan-Flint for a Mammalian Physiology course with the intent to expose students to an interactive research learning experience in which students design, conduct, and present findings. The results contained in this paper are conclusive only to the student members within our group. Using the Student Biopac Laboratory System to measure an EEG did impose some limitations on our experiment. The Biopac system only allowed us to measure brain activity at O1. Other published experiments have measured brain waves at multiple regions on the cranium. Another constraints on our experiment was time. We were limited to 3 weeks to collect data and analyze our findings. Our sample size is small and is probably not large enough to be conclusive for the entire University of Michigan-Flint population. Methods & Materials This study included 5 students from the University of Michigan-Flint. All subjects signed a consent form and were aware of the tasks to be completed, as each sample was a member of the group conducting the experiment. Each person was asked not to chew gum 6 hours before testing. A Student Biopac Laboratory System was used to measure an EEG at O1 before and after chewing Trident spearmint flavored gum sugar-free. The test required 3 electrodes, which remained intact throughout the entire experiment. The first electrode was placed 1.5 inches beneath the lobule of the ear and served as a reference lead. The second electrode was placed 1 inch perpendicular from the middle of the helix. The third electrode was placed 1.5 inches from the second electrode and 1.5 inches

3 from the tip of the helix. An online Stroop test was used to measure cognition ( Students were allowed to practice the Stroop test for 1 minute prior to beginning testing to eliminate any confusion as to the task that was expected. When running the actual testing, the Stroop test was measured for 1 minute before results were examined. Testing methods were kept constant for each student. Baseline EEG and cognition were taken before any gum chewing to serve as a control. Students were seated in a comfortable relaxed position with eyes closed in a quiet room for 5 minutes before running the baseline EEG. During the EEG testing, students were asked to keep eyes closed for the first 20 seconds, open eyes without blinking for the next 20 seconds, and keep eyes closed for the last 20 seconds. After completion of the EEG (with no gum), students took the online Stroop test for 1 minute (with no gum). Students were immediately given gum and allowed to chew, at his/her own pace, for 5 minutes (same settings as above), they were asked to not chew while running the second EEG. Students then repeated the Stroop Test for 1 minute while chewing gum at his/her own pace. Analysis of the data from the EEG was done for alpha, beta, theta, and delta waves electronically. An area that represented one cycle in the alpha wave was selected by measuring from one peak to another peak. This was repeated for the first segment of eyes closed, eyes open, and the last segment of eyes closed. This was also repeated for beta, delta, and theta. Standard deviations were recorded for each cycle of alpha, beta, delta, and theta for the first segment of eyes closed, eyes open, and the last segment of eyes closed. This measured the variability of data points in the amplitudes of the brain rhythms. Frequency was also recorded for alpha, beta, delta, and theta for the first segment of eyes closed, eyes open, and the last segment of eyes closed. The frequency converted the time segment of the cycle to frequency in cycles/sec. Analysis for the Stroop test was completed comparing the mean normal time before and after chewing, and mean interference time before and after chewing gum. Results Statistical analysis using a paired t-test was performed using Excel 2011 with the addition of StatPlus software for Mac. Histograms were created to see if the data were normally distributed. Analysis shows no significant difference (P>0.05) between the means for alpha, beta, delta, and theta brain waves before and after chewing gum. The values recorded during the EEG are in Table 1.1 below. Descriptive statistics for the t-test for each brain wave is recorded in Table 1.2 below. Table 1.1: EEG Measurements of Brain Waves Student Alpha No Gum Alpha Gum Beta No Gum Beta Gum

4 Delta No Gum Delta Gum Theta No Gum Theta Gum Table 1.1: Values above were measured using the Student Biopac Laboratory System. The values recorded for each student is the mean for the brain wave under conditions: closed eyes for 20 seconds, open eyes for 20 seconds, and closed eyes for 20 seconds. Table 1.2: Descriptive Statistics for EEG Brain Wave Measurements Variance Brain Wave Mean T-calculated T-critical Alpha- No Gum Alpha- Gum Beta- No Gum Beta- Gum Delta- No Gum Delta- Gum Theta- No Gum Theta- Gum Table 1.2: Contains descriptive statistics for the brain waves measured during the EEG. The degree of freedom used was 10. The probability of random chance was at 5%. Values from the Stroop test were also analyzed statistically using the paired t-test. The mean values for normal and interference time before and after gum were not significantly different (P>0.05). The values for the times are recorded in Table 2.1 and the descriptive statistics are found in Table 2.2 below. Table 2.1: Values of Normal and Interference Time during Stroop Test Normal No Gum (ms) Interference No Gum (ms) Normal Gum (ms) Interference Gum (ms) Table 2.1: Normal time refers to the time that it took for a student to respond to the color (that was correctly labeled as that color) after it initially was given. Interference time refers to the time it took a student to name a color in which the name of the color was not the same as the actual color.

5 Table 2.2: Descriptive Statistics for Stroop Test Mean (ms) Variance (ms) t-calculated t-critical Nomal time- No Gum , Normal time- Gum , Interference time- No Gum 1, , Interference time- Gum , Table 2.2: The table includes the mean times for normal time and interference time in milliseconds, which are described in the introduction. Discussion There is controversy over whether there truly are positive cognitive affects from chewing gum as research has mixed results due to the variation in experimental designs, lack of baseline cognition, low sample sizes, rate of mastication, and possible bias by the samples themselves who are aware of the studies goals. It is also unclear as to whether the effects of gum on cognition and EEG s are due to the act of mastication or to the stimulating effects of the spearmint flavor. More research is needed to verify these findings, as was the intent of this experiment that was a requirement for physiology class. The results of our experiment do not support previous findings that gum increases cognition. Our experiment supports the evidence indicating there is no difference between cognition before chewing gum and after chewing gum. There could be problems with these findings such as low sample size, not waiting long enough for the full effects of chewing to be measured, or having subjects chew gum during testing. Our experiment does support previous studies showing that cognition is not improved if the subjects chew gum during testing and that cognition is not improved after chewing for 5 minutes. The results of our EEG also showed no significant difference between alpha, beta, delta, and theta brain waves before and after chewing gum. These results could be due to errors in experimental design, lack of time, or insufficiencies in equipment availability. Previous experiments using EEGs measured brain waves at several different cranial regions. Our experiment was limited to O1. This experiment could indicate there are no changes in brain waves at this region although Morinushi et al (2000) had found there are significant changes. Again, it is possible 5 minutes is not sufficient time for the full effects to be seen. This experiment was conducted as a class requirement to introduce the concept and act of research in Physiology. All data contained in the article were obtained from group members who designed, conducted, and evaluated the experiment.

6 References Baker, J.R., Bezance, J.B., Zellaby, E., Aggleton, J.P. October 2004.Chewing gum can produce context-dependent effects upon memory. Appetite; 43(2): Hawegawa, Y., Ono, T., Hori, K., Nokubi, T. (2007). Influence of Human Jaw Movement on Cerebral Blood Flow. J Dent Res.; 86(1): Kubo, Kin-ya., Ichiashi, Yukiko., Kurato, Chika., Iinuma, Mitso., Mori, Daisuke., Katayama, Tasuku., Miyake, Hidekazu., Fujiwara, Shu., Tamura, Yasou Nov. Masticatory function and cognitive function - A review. Okaliimas Folia Anat. Jpn.; 87(3): Masumoto, Y., Morinushi, T., Kawasaki, H., Ogura, T., Takigawa, M Effect of three principle constituents in chewing gum on Electroencephalogram. Psychiatry and Clinical Neurosciences; 53: Momose, T., Nishikawa, J., Watanabe, T., Sasaku, Y., Senda, M., Kuboa, K., Sato, Y., Funakoshp, M., Minakuchi, S., Effect of Mastication on Regional Cerebral Blood Flow in Humans Examined by Positron-Emission Tomography with 150-Labed Water and Magnetic Resonance Imaging. Archs. Oral Biol; 42(1): Morinushi, T., Masumoto, Y., Kawasaki, H., Takigawa, M. December Effect on electroencephalogram of chewing flavored gum. Psychiatry and Clinical Neurosciences; 54(6): Onyper, S.V. Carr, T.L., Farrar, J.S., Floyd, B.R. May Cognitive advantages of chewing gum. Now you see them, now you don t. Appetite; 57(2): Tucha, L., Simpson, W. November The role of time on task performance in modifying the effects of gum chewing on attention. Appetite; 56(2):