The Effects of Group Therapeutic Singing on Cortisol and Motor Symptoms in Persons With Parkinson's
The inclusion of music into the treatment plan for persons with Parkinson's disease (PD) may be a viable strategy to target multiple motor symptoms. However, potential mechanisms to explain why music has an impact on multiple motor symptoms in persons with PD remain understudied. The purpose of this study was to examine the acute effects of 1 h of group therapeutic singing (GTS) on physiological measures of stress and clinical motor symptoms in persons with PD. We posit that improvement in motor symptoms after GTS may be related to stress reduction. Seventeen participants with PD completed 1 h of GTS and eight participants completed 1 h of a quiet reading (control session). Cortisol was collected via passive drool immediately before and after the singing and control session. The Unified Parkinson's Disease Rating Scale (UPDRS) Part-III (motor examination) was also video-recorded immediately before and after the singing and control session and scored by two raters masked to time and condition. Secondary outcome measures for quality of life, depression, and mood were collected. Results revealed no significant change in cortisol or motor UPDRS scores, as well as no significant relationship between cortisol and motor UPDRS scores. There was a trend for the singing group to report feeling less sad compared to the control group after the 1-h session (effect size = 0.86), and heart rate increased in the singing group while heart rate decreased in the control group after the 1-h session. These results suggest that an acute session of GTS is not unduly stressful and promotes the use of GTS for persons with PD. Multiple mechanisms may underlie the benefits of GTS for persons with PD. Further exploring potential mechanisms by which singing improves motor symptoms in persons with PD will provide greater insight on the therapeutic use of music for persons with PD.
Over the next 20 years, the prevalence of Parkinson's disease (PD) is likely to double. Yet, there is no cure. Current predominant forms of treatment (i.e., drug therapy and deep brain stimulation) provide substantial relief but have significant side effects and are expensive (Borgohain et al., 2012; Borovac, 2016), and many symptoms of PD are not fully ameliorated by current treatments. Thus, there is a pressing need to develop therapeutic strategies that limit side effects, reduce treatment costs, and target multiple symptoms of PD.
Dance and music have been incorporated into current treatment strategies for PD. Learning and performing ballroom dance steps improved functional mobility, gait, and postural stability (Hackney and Earhart, 2009, 2010; Foster et al., 2013). Ballet and Irish dancing have resulted in acute improvements in functional mobility and postural instability (Houston and McGill, 2013; Volpe et al., 2013). Drumming has been shown to improve walking rate in persons with PD (Pantelyat et al., 2016). Our group has shown that group therapeutic singing (GTS) improved respiratory control, swallow, and quality of life (Stegemöller et al., 2016, 2017a). The singing groups were enjoyable for participants as they offered a way to relieve stress and have fun (Stegemöller et al., 2017b). Participants also viewed the groups as an avenue to express their concerns about having PD and build camaraderie with other people with PD (Stegemöller et al., 2017b). Taken together, this suggests that the inclusion of music into the treatment plan for persons with PD may be a viable strategy to target multiple motor symptoms as well as improve mood and quality of life.
Building on evidence showing promising outcomes, the next step is to uncover potential mechanisms to explain why music has an impact on multiple motor symptoms in persons with PD. The positive benefits of dance and drumming in PD may be related to increased physical activity as prior studies have shown that participation is associated with improvements in balance, gait, risk for falls, physical function, sleep cognition, and quality of life (Feng et al., 2020). However, it remains challenging to isolate the benefits of music vs. physical activity. GTS does not require an overt amount of physical activity, yet various motor symptoms and quality of life are improved. Further exploring the mechanism by which singing improves motor symptoms in persons with PD will provide greater insight on the therapeutic effects of music alone.
Building from our previous research revealing that participants with PD reported feeling less stressed after group therapeutic singing (Stegemöller et al., 2017b) and research that demonstrated music and singing can reduce perceived stress and reduce cortisol in various clinical populations (Miluk-Kolasa et al., 1994; Scheufele, 2000; Khalaf et al., 2003; Fukui and Toyoshima, 2008; Bradt et al., 2014; Fancourt et al., 2016), we posit that the improvement in motor symptoms may be due to reduced stress. When persons with PD experience stress, their motor symptoms frequently worsen (van der Heide et al., 2021). Indeed, when clinically evaluating tremor, patients are often given a mild cognitive stressor (i.e., count backwards by three) to trigger the emergence of tremor. To our knowledge, no study has examined the effects of singing on stress (or stress reduction) in persons with PD. The purpose of this study is to determine the acute effects of group therapeutic singing on clinical motor symptoms and stress. We hypothesized that after 1 h of singing, (1) clinical motor scores would improve, (2) cortisol, a biomarker of stress, would decrease, and (3) there would be a relationship between improved clinical motor scores and cortisol.
Twenty-five participants were enrolled into the study. Inclusion criteria included age between 40 and 85, a diagnosis of PD, and on the same PD medication for the past 30 days. Exclusion criteria included a score <24 on the Mini Mental State Exam. Demographic. Disease information at the day of study enrollment is shown in Table 1. All participants were tested on their optimal PD medication, following their regular timing and dosage, as prescribed by their treating physician. Time since last PD medication is shown in Table 1. All participants gave written informed consent prior to inclusion in the study, and the Institutional Review Board of Iowa State University approved the procedures. Participants were recruited from ongoing GTS groups in surrounding areas as well as from a general listserve of persons with PD interested in research. Participants currently participating in a GTS group were assigned to the singing intervention group. Those participant not currently participating in a GTS group were assigned to the control group. This resulted in 17 participants enrolled in the singing session, and eight participants enrolled in the control session.
Seventeen participants completed 1 h of GTS. The singing session began with a greeting song lasting ~5 min. A series of vocal exercises lasting ~15 min followed the greeting song and included diaphragmatic breathing exercises, lip buzzing, glissandos, and articulation exercises. The vocal exercises have been used in previous group therapeutic singing studies.11−13 Specific songs targeting pitch range, articulation, and breath support followed the vocal exercises for ~15 min. Participants were then asked to choose songs they would like to sing for ~20 min. The session concluded with a closing song lasting ~5 min. Participants completed all songs and vocal exercises without written music or lyrics. A review of lyrics was provided as needed prior to singing each song. Participants were instructed to sit with appropriate posture, breathe from the diaphragm, lift the palate, and show facial expression while singing. A piano was used to accompany the vocal exercises and songs. The session was led by a board certified music therapist with over 15 years' experience leading therapeutic singing groups for persons with PD.
Eight participants completed 1 h of a control (i.e., no singing) session. Participants were instructed to sit in a quiet room together and read quietly for 1 h. The room was in the same building where the singing sessions were held.
Data collection for both groups were completed using the same location. Prior to completing the singing or control session, participants completed a series of questionnaires. The Parkinson's Disease Questionnaire (PDQ-39) was collected as a measure of quality of life and the Beck Depression Index (BDI) was collected as a measure of depression (Jenkinson et al., 1997; Goodarzi et al., 2016). The total Unified Parkinson's Disease Rating Scale (MDS-UPDRS) was collected as a measure of disease severity (Martinez-Martin et al., 2013). Number of years singing in the therapeutic singing group was also collected (Table 1). In addition, a daily diary was completed documenting food intake, exercise, tobacco use, and unusual events for 24 h prior to data collection. The daily diary also included a subjective report of anxiety, anger, happiness, and sadness on a scale from 1 to 7. This scale was completed prior to and after the singing or control session and served as secondary outcome measures for further exploratory analyses (Table 2). Resting heart rate and blood pressure collected pre and post-session are shown in Table 2.
Unified Parkinson's Disease Rating Scale
The motor MDS-UPDRS was used as the primary outcome measure for clinical motor symptoms. The scale was administered by a trained rater immediately before and after the singing session. Video recordings were completed and later scored by two movement disorders neurologists that were masked to the study. The neurologists were not informed of the intervention used (i.e., singing or control), and the videos were coded to mask pre or post-intervention order.
The primary outcome measure of cortisol, a widely used marker of stress, was collected immediately before and after the singing session via passive drool into sterile Wheaton Cryogenic 2 ml vials. The sessions were held from 3 to 4 p.m. central standard time, so the sample was collected within 30 min before and 30 min after the sessions. Because salivating can be challenging for patients with PD, we provided participants with water 5 min prior to sample collection, and participants were taught to use a chewing motion to enhance flow. To limit potential stress of providing a sample, participants were instructed that they had 5 min to complete the sampling and that whatever they were able to produce was sufficient. For cortisol, only 50 μL of saliva is needed for duplicate tests, which most participants provided within 1–2 min. Samples were frozen within 1 h at −80°C for later analysis.
Cortisol was analyzed with the Salimetrics® Cortisol Enzyme Immunoassay Kit, a commercially-available FDA cleared kit with a wide detection range (0.007 ug/dL−3 ug/dL) and minimal cross-reactivity with other biomarkers. Saliva was assayed in duplicate. Duplicates that varied by >7% were re-assayed. With each assay plate, a standard curve was calculated; standard curves that were R < 0.997 were re-assayed. High and low controls were also calculated with each assay plate; controls that are out of range or varied by >20% were re-assayed. Duplicates were averaged, reported as ug/dL, and inspected for normality. Typical for cortisol, the distribution was skewed, so the data were winsorized and log-transformed.
Normality was tested using the Shapiro-Wilk test. Data followed approximately a normal distribution, including cortisol which was transformed. Independent-sample t-tests were conducted for the two sets of motor UPDRS scores to determine if there were differences between the masked raters' scores. No significant differences were revealed (pre-session scores: p = 0.48; post-session scores: p = 0.55). Therefore, the average of the two motor UPDRS scores was calculated and used for the remaining statistical analyses. Independent-samples t-tests probed for differences between groups for the demographic data, disease information data, and change scores (post-value–pre-value) for the secondary outcome measures, heart rate, and blood pressure. Effect sizes using Hedges' g were calculated, as sample sizes were different between groups.
To test the hypothesis that clinical motor scores will improve and cortisol will decrease after an acute session of singing, a 2 (pre- and post-session scores) × 2 (singing vs. control group) repeated measures ANOVA was estimated for each primary outcome measure (motor UPDRS and cortisol). Any demographic or disease variable that was found to be significantly different between groups was entered as a covariate in the ANOVA. Post-hoc analyses were completed using Tukey's Honestly Significant Difference test. Significance was set at p < 0.05. To determine if there was a difference in the magnitude of change in the primary outcome measures (motor UPDRS and cortisol) between groups, independent-samples t-tests were conducted using the change scores (post-value–pre-value).
To test the hypothesis that there was a relationship between clinical motor scores and cortisol, a Pearson product-moment correlation was estimated to determine the relationship between motor UPDRS and cortisol across both groups, and for the singing group and control group separately. Change scores were calculated (post-value–pre-value) and used as data for the Pearson correlation.
Additional exploratory analyses were completed to determine if demographics, disease information, or change in secondary outcome measures (i.e., subjective reports of anxiety, anger, happiness, and sadness) account for the change in motor UPDRS scores or cortisol. A stepwise linear regression model was used to determine the predictors of the change in each primary outcome measure (motor UPDRS and cortisol) for both groups combined and for each group separately (singing and control). Using change scores for the primary outcome measures, participants were categorized based on their response (decrease or increase/no change). A chi-square test for differences in the percentage of participants in each group (singing vs. control) demonstrated a decrease in motor UPDRS scores. A parallel separate chi-square test for difference in the percentage of participants in each group demonstrated a decrease in cortisol. Significance was set a p < 0.05. Effect sizes using Cramer's V were calculated for the chi-square tests.
Data from the daily diary indicated that all participants had eaten a meal within 3 h before the first data collection, nine of the participants (five in the singing group, four in the control group) had exercised on the day of the data collection (all ~5 h prior), no participants used tobacco, and there were no significant unusual events within 24 h prior to the first data collection. Comparisons between groups for demographic and disease information revealed a significant difference for only the BDI [t(23) = 2.36, p = 0.03, g = 1.01]. The singing group had a higher score than the control group. No other comparisons attained statistical significance (Table 1). For blood pressure and heart rate, results revealed a significant difference between groups for heart rate only [t(23) = 2.17, p = 0.04, g = 0.93]. Heart rate increased after the session for the singing group while heart rate decreased after the session for the control group (Table 2). For the secondary outcome measures (participant reports of mood) there were no significant differences between groups, although there was a trend for the singing group to report feeling less sad than the control group [t(23) = −1.99, p = 0.06, g = 0.86] (Table 2).
Original Source and full article: https://www.frontiersin.org/articles/10.3389/fnhum.2021.703382/full