Association Between Transcranial Direct Current Stimulation and Disability and Quality of Life in Individuals with Parkinsonism. Cross-sectional Study

RAVI SHANKAR REDDY^1,2*Jaya Shanker Tedla^1,2Irshad Ahmad¹Venkata Nagaraj Kakaraparthi¹Snehil Dixit¹Kumar Gular¹Paul Silvian¹Suhail Mansour Aljehani¹Feras Ahmed Alarabi¹

• ¹Program of Physical Therapy, Department of Medical Rehabilitation Sciences, College of Applied Medical Sciences, King Khalid University, Abha 61421, Saudi Arabia, Abha, Saudi Arabia
• ²King Salman Center for Disability Research, Riyadh, Saudi Arabia

Background: Parkinsonism is a progressive neurodegenerative disorder characterized by motor and non-motor impairments, significantly impacting quality of life (QoL).Transcranial direct current stimulation (tDCS) has shown promise in improving motor and cognitive functions when combined with physical therapy. This study aimed to explore the association between tDCS exposure and disability levels, as well as its impact on self-reported QoL in individuals with Parkinsonism undergoing physical therapy.: This cross-sectional study enrolled 51 participants diagnosed with Parkinsonism from a tertiary care hospital's neurology outpatient clinic. Based on clinical records of tDCS sessions, participants were stratified into tDCS-exposed and nonexposed groups. Disability was assessed using the World Health Organization Disability Assessment Schedule, and QoL was measured using the Parkinson's Disease Questionnaire (PDQ-39). Statistical analyses included t-tests for comparing means and Pearson correlation coefficients for assessing relationships between tDCS exposure, disability, and QoL.The tDCS-exposed group demonstrated lower mean disability scores (WHODAS 2.0: 42.50 ± 8.12) and better quality of life scores (PDQ-39: 35.10 ± 6.45) compared to the non-exposed group (WHODAS 2.0: 45.30 ± 9.21; PDQ-39: 40.15 ± 7.32); however, these differences were not statistically significant (disability: p = 0.131; QoL: p = 0.236). Subgroup analyses revealed statistically significant improvements among participants under 65 years of age (disability mean difference = -3.3, 95% CI: -6.17 to -0.43, p = 0.023) and those in Hoehn and Yahr stages 1-2 (QoL mean difference = -3.7, 95% CI: -6.16 to -1.24, p = 0.004). Additionally, a moderate negative correlation was observed between tDCS session frequency and disability scores (r = -0.60, 95% CI: -0.78 to -0.30, p = 0.04), and a weak negative correlation with quality of life scores (r = -0.43, 95% CI: -0.66 to -0.11, p = 0.039).These findings suggest possible associations between tDCS exposure and clinical outcomes in individuals with Parkinsonism; however, due to the cross-sectional design and underpowered subgroup analyses, results should be interpreted with caution and viewed as hypothesis-generating.