Abstract
Background: Attention is crucial to voluntary perform actions in Parkinson’s disease (PD), allowing patients to bypass the impaired habitual motor control. The asymmetrical degeneration of the dopaminergic system could affect the attentional functions.Objective: To investigate the relationship between the asymmetric dopaminergic degeneration and the attentional resources in Parkinsonian patients with right-side (RPD) and left-side (LPD) motor symptoms predominance.Methods: 50 RPD, 50 LPD, and 34 healthy controls underwent visual (V), auditory (A), and multiple choices (MC) reaction time (RTs) tasks. For PD patients, these tasks were performed before and after a 4-week intensive, motor-cognitive rehabilitation treatment (MIRT). The effectiveness of treatment was evaluated assessing Unified Parkinson’s disease Rating Scale (UPDRS) III and Timed-up and Go Test (TUG).Results: RTs did not differ between PD patients and healthy controls. Before MIRT, no differences between LPD and RPD patients were observed in RTs (p = 0.20), UPDRS III (p = 0.60), and TUG (p = 0.38). No differences in dopaminergic medication were found between groups (p = 0.44 and p = 0.66 before and after MIRT, respectively). After MIRT, LPD patients showed a significant reduction in MC RTs (p = 0.05), V RTs (p = 0.02), and MC-V RTs. A significant association between changes in RTs and improvements in UPDRS III and TUG was observed in LPD patients.Conclusion: attention does not differ among RPD patients, LPD patients and healthy controls. Only LPD patients improved their performances on attentional tasks after MIRT. We argue that the increased early susceptibility of the left nigrostriatal system to degeneration affects differently the cognitive modifiability and the neuroplastic potential. Our results could provide insight into new therapeutic approaches, highlighting the importance to design different treatments for RPD patients and LPD patients.
Highlights
Parkinson’s disease (PD) is the second most common neurodegenerative disorder characterized by different motor and non-motor symptoms
In order to understand to what extent dopamine-related asymmetry affects attention and the cortical functioning, in this study we have examined specific attentional processes (Posner and Petersen, 2012) in right-side motor symptoms predominance (RPD) patients, left-side motor symptoms predominance (LPD) patients and healthy controls, separately
Dopamine-related asymmetry seems to play a role on the modifiability of the attentional resources, as we found that a motor-cognitive, intensive and goal-based rehabilitation treatment is effective in improving attention in LPD patients, but none in RPD patients
Summary
Parkinson’s disease (PD) is the second most common neurodegenerative disorder characterized by different motor and non-motor symptoms. The lateralization of motor symptoms is associated with a more severe contralateral degeneration of dopaminergic neurons (Haaxma et al, 2010), which is in turn responsible for a hypodopaminergic state in the striatum and frontal regions (Marie et al, 1995; Mattay et al, 2002; Cheesman et al, 2005). In a review of 36 published studies, Verreyt et al (2011) concluded that PD patients with right-side motor symptoms predominance (RPD) mostly present problems in language and verbal memory tasks, whereas PD patients with left-side motor symptoms predominance (LPD) show impairments in visuospatial orienting, spatial attention and mental imagery (Verreyt et al, 2011). Attention is crucial to voluntary perform actions in Parkinson’s disease (PD), allowing patients to bypass the impaired habitual motor control. The asymmetrical degeneration of the dopaminergic system could affect the attentional functions
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