Stressbusters: a pilot study investigating the effects of OMT on stress management in medical students

Study population

Participants were recruited from the first-year medical student class at the TouroCOM Harlem campus. Participants were required to be first-year students who were not already receiving regular OMT from an osteopathic physician, who were able to satisfy the time commitments, and who did not attend weekly TouroCOM Harlem OMM enhancement sessions during the duration of the study. While students participated in weekly OMT labs, the classes were standardized so that all participants received the same treatments on any given day. Participants who did not fit in the aforementioned criteria were excluded from the study. The study also excluded participants who were pregnant, had spinal surgery in the past, or had any underlying condition that would be a contraindication to OMT. While we did not perform an in-depth review of participants’ medical history, we also attempted to exclude any participants with disclosed chronic medical conditions such as anxiety, diabetes, or hypertension. This study did not involve participants from protected or vulnerable populations. This study considered all interested individuals for the study without attention to race, color, religion, sex, sexual orientation, gender identity, national origin, veteran, or disability status.

The recruitment process consisted of sending an email to the entire first-year medical student class utilizing the TouroCOM Harlem List Serv function, and interested individuals were invited to fill out a secure Google form. A total of 10 respondents were selected based on eligibility and 6-week availability. Our sample size was limited not due to lack of interest, but rather due to lack of availability for regular weekly sessions as a consequence of the rigorous medical school schedule.

Study design

Ten participants (2 males, 8 females; age range, 23–28 years; mean age, 25 years) were randomly split into two equal groups of five control (1 male, 4 females; age range, 23–28 years; mean age, 25 years) and five treatment (1 male, 4 females; age range, 23–28 years; mean age, 25 years), and they underwent a designated protocol for 6 weeks.

Participants were asked to report to an assigned private Objective Structured Clinical Examination (OSCE) room on the TouroCOM Harlem campus at their designated times. All student subjects were kept in treatment rooms for 30 min and kept the same appointment time across all weeks to avoid natural cortisol fluctuations. For the first 15 min of the session, all participants were asked to complete a cognitive workout on Lumosity to establish their baseline scores and also complete the CSSS. Participants were then asked to provide saliva samples for the cortisol assay. The subjects in the treatment cohort would then receive 15 min of OMT, whereas the nontreatment subjects stayed in the treatment rooms for 15 min before being dismissed. These samples were stored in a secure lab fridge on the TouroCOM Harlem campus. For the following 5 weeks, participants adhered to a strict schedule requiring their presence in designated private OSCE rooms at specified intervals. Figure 1 visualizes the chronological order of the experimental protocol utilized for the rest of the study.

Figure 1:

Participant flow diagram.

All participants were assigned one of five OMM student-teaching assistants for weekly assessment. Treatment providers were not blinded as to which participants were to receive treatment and which participants were not. The OMM student-teaching assistants treated the same participants for the duration of the study; there were no substitutions. All treatment providers were standardized with their level of training and protocol adherence.

Individuals in the experimental cohort received OMT on a weekly basis based on a systematic treatment protocol consisting of paraspinal inhibition, rib raising, and condylar decompression techniques performed by OMM student-teaching assistants with attending supervision. The control cohort was not given any form of therapeutic intervention. Concurrently, participants’ salivary cortisol levels were collected at the beginning of each session at a standardized time prior to any treatment or survey data collection and analyzed utilizing an Invitrogen enzyme-linked immunosorbent assay (ELISA) Immunoassay Kit. Additionally, cognitive function was assessed weekly via Lumosity, whereas perceived stress levels were gauged utilizing the CSSS. Control group participants were isolated for the same amount of time as the treatment group participants but did not receive OMT.

All five student researchers participated in providing the three-technique OMM treatment regimen to the participants, collecting salivary samples for the cortisol assay, and administering the CSSS survey and Lumosity assessment. RV performed the statistical analysis on all the collected data utilizing Prism 10. The two faculty members served as supervisors during the participants’ treatment slots and reviewed every stage of the treatment process.

Data collection

All participant salivary samples were collected at the beginning of each session at 2 pm for 6 weeks and stored in a (−4 °C) refrigerator. These samples were analyzed utilizing an Invitrogen ELISA Immunoassay Kit. 100 uL of each sample was diluted in 200 uL of Assay Buffer and processed according to the procedure outlined by the manufacturer. The samples were actually analyzed using the SoftMax 7.2 software tool. The standard cortisol concentration samples provided with the assay showed an inversely proportional exponential relationship to the optical density (OD) at 450 nm. The line of best fit for standard cortisol concentration (y axis) against OD at 450 nm (x axis) was calculated to be y=9,667.93, * 0^x with a correlation coefficient of 0.99.

Changes in participant cognitive function was assessed each week utilizing Lumosity, a website designed to assess and strengthen cognitive function through a series of games. Despite claims by the website to improve cognitive function, studies conducted by Florida State University showed that short-term usage of Lumosity did not significantly improve cognitive performance; however, a review conducted on the use of brain games in attention and cognition rehabilitation showed that Lumosity is a commonly utilized tool for cognitive assessment [10], 11]. Due to the short-term nature of this investigative study, we utilized Lumosity as a benchmark rather than a cognitive improvement tool, to measure weekly cognitive function. Each week, participants completed a “workout” consisting of three different exercises that assessed various cognitive functions to receive a Lumosity Performance Index (LPI) and subscores for speed, memory, attention, flexibility, and problem solving.

In addition to salivary cortisol measurements for physical stress, perceived stress levels of the participants were also measured utilizing the CSSS. CSSS is a subjective 11-item survey that utilizes a scale of 1–5 to measure undergraduate student stress over an academic year due to various factors [12]. The survey was modified to ask how often the participant perceived an aspect of stress within the last week. A score of 1 indicated no stress while 5 indicated significant stress; the scores were added together for subsequent analysis.

Treatment description

Certain treatment modalities of OMM focus on treatments designed to regulate sympathetic tone. Regulation of sympathetic tone is crucial in managing stress promoting a balanced physiological state through regulation of the autonomic nervous system [13].

An example of a sympathetic regulatory technique is paraspinal inhibition, a gentle, passive technique targeting the fascia surrounding the spine, aimed at reducing sympathetic output by affecting the sympathetic chain ganglia in the paraspinal region from T1-L2. Another technique, supine rib raising, was employed to address the restricted excursion of the rib cage, a direct method to regulate thoracic sympathetic chain ganglia activity by encouraging normalized articulation with the thoracic spine. Additionally, condylar decompression, a passive, direct cranial technique, is aimed at freeing local restrictions around the occipitoatlantal joint to normalize parasympathetic tone in the vagus nerve, a mechanism that is a focus in this study to decrease cortisol levels given its innervation of hormone-producing organs. While the sacrum is a prominent region for parasympathetic innervation, we believed that omission of sacral regulation techniques would not significantly impact our ability to assess parasympathetic modulation through vagal tone [13].

The rationale behind employing these osteopathic techniques is rooted in the overarching goal of OMM to restore functionality and to normalize physiologic barriers in range of motion by utilizing the relationship between the neuromusculoskeletal system and other bodily systems [14].

Statistical methods description

In our study, we employed an unpaired t-test, the Mann–Whitney U test, and effect-size calculation to analyze the impact of OMTs on cortisol levels in medical students. The unpaired t-test was utilized to compare the average weekly changes in cortisol levels (measured through OD) between the treatment and control groups, assessing whether the difference in means was statistically significant. Considering our small sample size and the potential for a nonnormal distribution of cortisol levels, we also applied the Mann–Whitney U test, a nonparametric alternative to the t-test, to validate our findings. Finally, to quantify the magnitude of OMT’s effect on cortisol levels, we calculated the effect size utilizing Cohen’s d. This provided a standardized measure of the treatment’s efficacy, indicating a significant effect of OMT on reducing cortisol levels in the treatment group compared to the control group.

Changes in optical density

The study assessed the weekly change in optical density (∆OD) measured at 450 nm for both the treatment and control groups. The sample size for each group was n=5. The treatment group exhibited a mean ∆OD of 0.02 (median, 0.01; range, −0.005 to 0.05) with a standard deviation (SD) of 0.02, while the control group exhibited a mean ∆OD of −0.004 (median, −0.005; range, −0.003 to 0.005) with an SD of 0.006. The average ∆OD of the treatment and control groups, along with the ∆OD change of each participant, is shown in Table 1.

Based on the CSSS responses, there was no statistically significant difference in perceived stress between the control and treatment groups (p=0.9, two-tailed). The mean weekly change in perceived stress scores was −1.1 (median, −1.7; range, −1.8 to 1; SD=1.2) for the treatment group and a mean of −1.2 (median, −1.4; range, −2.2 to 0.7; SD=1.1) for the control group, with a negligible effect size (R²=0.003). The CSSS score change for both groups is visualized in Figure 2.

Figure 2:

Average weekly changes in College Student Stress Scale (CSSS) score.

A two-tailed t-test to compare the average ∆OD between the treatment and control groups. The t-test yielded a t value of 2.3 with 8 degrees of freedom (df), resulting in a p value of 0.049, which is statistically significant at the p<0.05 level, as shown in Figure 3. This test produced a p value of 0.03, further supporting statistical significance. The effect sizes were calculated utilizing the means and SDs. Cohen’s d was found to be 1.5, and the effect-size r was 0.6. The power of this study is calculated to be 53 %.

Figure 3:

Average weekly changes in optical density (∆OD).

Analysis of the change in LPI revealed no statistically significant difference in cognitive performance between the treatment and control groups (p=0.9, two-tailed). The mean change in LPI scores was 85.6 (median, 67.5; range, 39–196; SD, 68.5) for the treatment group and 81.1 (median, 82.2; range, 13–173; SD=38.3) for the control group, with a minimal effect size (R²=0.001). The LPI score change for both groups is visualized in Figure 4.

Figure 4:

Average weekly change in Lumosity Performance Index (LPI).

Limitations

The major limitation of this study was the 10-person sample size. Even though a statistically significant difference in ∆OD (and indirectly cortisol levels) was found between the experimental and control groups, a larger sample size could have provided a stronger correlation between OMT and a reduced rate of cortisol increase in first-year medical students. Despite achieving a statistically significant difference in cortisol levels between the treatment and control groups (p=0.0317), the power analysis revealed a power of approximately 53 %, suggesting that while the findings are promising, a larger sample size would be needed to confirm these results. A large sample size could have also helped determine if there was a correlation between subjective perception of stress and OMT or a link between OMT and cognitive performance.

Another major limitation of this study arises due to the difficult nature of stress quantification. Even though cortisol is regarded as the gold standard of physiological stress markers, salivary cortisol levels fluctuate throughout the day and can be affected by external factors such as caffeine intake, physiological health, and daily activities [18], 19]. We chose not to exclude caffeine intake or stimulant use, because doing so would have significantly limited the study population. Instead, we focused on observing longitudinal changes in cortisol levels relative to each participant’s personal baseline.

Additionally, the study design only allowed us to obtain weekly salivary cortisol samples, which provides only a snapshot at the participant’s cortisol levels and indirectly their physiological stress level. The weekly measurements made it more difficult to account for external influencers of cortisol levels during the data analysis due to limited data points. More frequent or continuous salivary cortisol measurements would have provided better insight into how participants’ salivary cortisol levels and physiological stress levels change in the control and experimental groups due to OMT.

One limitation of the survey methodology was that it did not account for any stress management activities and techniques that each participant utilized in their everyday lives. A future study can expand on this pilot study and see whether OMT can work adjunctively with other stress management techniques or to compare the efficacy of OMT vs. other activities such as yoga, meditation, or regular exercise.