Objective: To explore associations between cardio-respiratory fitness (VO2peak), cortico-spinal excitability (CSE) and motor learning in people with Parkinson’s Disease (PwPD).

Background: PwPD show alterations in different measures of corticospinal excitability (CSE) as a result of the degeneration of midbrain dopaminergic neurons¹. These alterations, which tend to be mitigated with dopaminergic medications, have been associated with disease severity and motor learning impairments^1,2. Regular cardiovascular exercise, which is usually associated with higher cardio-respiratory fitness (VO2peak), has shown to have the potential to normalize CSE alterations and improve motor learning in PwPD^3-5.

Method: Thirty-two PwPD in the early stages of the disease were tested on two separate days while ON and OFF dopaminergic medications. CSE measures assessed in 28 PwPD by applying transcranial magnetic stimulation over the contralateral M1 to the dominant hand included resting (REX) and active excitability (AEX), short intracortical inhibition (SICI) and facilitation (ICF), as well as the cortical silent period (CSP). In 32 PwPD, motor learning was assessed while OFF medication with a visuomotor tracking task performed with the dominant hand and VO2peak with a graded exercise test. Differences in CSE measures between ON and OFF medication status and associations between VO2peak, CSE, and motor learning capacity were tested with Student’s t-tests and Pearson’s correlations, respectively.

Results: No differences in CSE measures between ON and OFF medications were found. VO2peak was associated with AEX (F_(1,26) = 5.67; r = 0.411; p = 0.027) and CSP (F_(1,26) = 13.22; r = -0.541; p = 0.003) while ON medications and with AEX (F_(1,26) = 11.44; r = 0.559; p = 0.002), SICI (F_(1,26) = 7.65; r = -0.464; p = 0.013), and ICF (F_(1,26) = 6.82; r = 0.456; p = 0.013) while OFF medications. Higher VO2 values were associated with greater motor learning capacity (F_(1,29) = 9.92; r = 0.499; p = 0.004).

Conclusion: PwPD with higher cardio-respiratory fitness levels show better motor learning capacity and less pronounced alterations in M1, particularly during the OFF state. These findings add new evidence to previous studies^3-5 suggesting that exercise could be a valuable intervention to reduce motor learning impairments and abnormalities in cortico-spinal networks.

References: 1 Underwood, C. F. & Parr-Brownlie, L. C. Primary motor cortex in Parkinson’s disease: Functional changes and opportunities for neurostimulation. Neurobiol Dis 147, 105159 (2021). https://doi.org:10.1016/j.nbd.2020.105159
2 Udupa, K., Bhattacharya, A., Bhardwaj, S., Pal, P. K. & Chen, R. Parkinson’s disease: Alterations of motor plasticity and motor learning. Handb Clin Neurol 184, 135-151 (2022). https://doi.org:10.1016/b978-0-12-819410-2.00007-2
3 Duchesne, C. et al. Enhancing both motor and cognitive functioning in Parkinson’s disease: Aerobic exercise as a rehabilitative intervention. Brain and Cognition 99, 68-77 (2015). https://doi.org:https://doi.org/10.1016/j.bandc.2015.07.005
4 Fisher, B. E. et al. The effect of exercise training in improving motor performance and corticomotor excitability in people with early Parkinson’s disease. Arch. Phys. Med. Rehabil. 89, 1221-1229 (2008). https://doi.org:10.1016/j.apmr.2008.01.013
5 Petzinger, G. M. et al. Exercise-enhanced neuroplasticity targeting motor and cognitive circuitry in Parkinson’s disease. Lancet Neurol 12, 716-726 (2013). https://doi.org:10.1016/s1474-4422(13)70123-6

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cardio-respiratory-fitness-is-associated-with-corticospinal-excitability-and-motor-learning-in-parkinsons-disease/