Effectiveness of Singing-Based Therapy on Voice Outcomes in Parkinson's Disease: A Systematic Review and Meta-Analysis

Abstract

Background: Communication impairments significantly impact the quality of life for individuals with Parkinson's disease (PD), underscoring the need for effective interventions. Singing, by engaging shared neural networks and structural mechanisms involved in speech production, holds therapeutic potential for addressing speech disorders in this population. This study explores the effects of singing-based therapeutic intervention on voice in patients diagnosed with PD.

Methods: We systematically searched four electronic databases to find relevant studies. Data extraction and analysis involved calculating mean differences (MD) or standardized mean difference (SMD) for pre- and post-singing interventions, including their 95% confidence intervals (CI). Statistical significance was evaluated with a P-value threshold >0.05.

Results: Our systematic review and meta-analysis included 21 studies, encompassing 449 patients. Singing showed no significant effect on speaking fundamental frequency (MD 2.98, 95% CI: -6.79, 12.75, P = 0.55), jitter (MD -0.13, 95% CI: -0.47, 0.22, P = 0.47), shimmer (MD -0.71, 95% CI: -1.68, 0.26, P = 0.15), or health-related quality-of-life outcomes: Voice Handicap Index (MD -4.60, 95% CI: -9.29, 0.09, P = 0.05) and Voice-Related Quality of Life (SMD 0.08, 95% CI: -0.28, 0.44, P = 0.65). However, singing significantly improved vocal frequency range (MD 2.60, 95% CI: 1.17, 4.03, P = 0.0004), maximum expiratory pressure (MD 14.26, 95% CI: 9.57, 18.96, P < 0.00001), maximum inspiratory pressure (MD 6.22, 95% CI: 2.96, 9.48, P = 0.0002), and maximum phonation time (MD 1.83, 95% CI: 0.73, 2.92, P = 0.001). Vocal intensity showed no significant difference (MD 1.09, 95% CI: -0.71, 2.88, P = 0.24).

Conclusion: Our study found that singing interventions positively affect vocal frequency range and respiratory outcomes. However, significant changes were not observed in other speech metrics.

Keywords: Maximal respiratory pressures; Parkinson disease; Singing; Speech; Speech disorders; Voice-related quality of life.