High-intensity interval vs. continuous moderate-intensity aerobic exercise for improving neurotransmitter level and neurocognitive performance in individuals with Parkinson's disease

Abstract

In individuals with Parkinson's disease (PD), cognitive impairments can cause their quality of life to deteriorate and aggravate their motor symptoms. No studies have yet explored the neurophysiological and neurobiochemical mechanisms of changes in cognitive processing underlying neuropsychological problems exhibited by this group. The current study aimed to investigate and compare the acute effects of high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE) on the neurocognitive performance and neurotransmitter levels of individuals with PD. In addition, the relationship between changes in neurocognitive performance and those in the peripheral dopamine level induced by HIIE and CMIE interventions were also examined. Using a within-subjects design, twenty-three participants with mild to moderate PD completed a single session of both HIIE and CMIE, as well as a session in a control condition (REST) in counterbalanced order. The neurocognitive indices of working memory [i.e., accuracy rate (AR), reaction time (RT), and latencies and amplitudes of N2 and P3 event-related potentials (ERPs)] were assessed. Blood samples were taken before and after the three intervention modes. During the working memory task, acute HIIE and acute CMIE brought about faster RTs and P3 ERP waves with higher amplitudes in individuals with PD. Furthermore, better ARs and a shorter N2 latency were associated with engaging in HIIE and CMIE, respectively. On the other hand, only the acute CMIE intervention was associated with significant increases in the plasma dopamine level. Finally, no significant correlation was obtained between changes in neurocognitive performance and those in the dopamine level which were assessed both before and after taking part in the interventions. For individuals with mild to moderate PD, acute HIIE and CMIE proved to be tolerable, safe, and effective modes of aerobic exercise. These types of exercise are well-suited to be practiced at home and in a community setting in order to decrease the risk of cognitive impairment in general and more specifically the risk of developing dementia as a comorbidity of PD. However, the acute benefits underlying the two dynamic forms of exercise appear to be intensity-dependent in PD.