Lateralization of Cognitive Deficits and Rehabilitation in Parkinson's Disease

Background: Parkinson's disease (PD) is a chronic and progressive neurodegenerative disease which is associated with significant loss of dopaminergic cells in the substantia nigra. This loss results in disruption to a number of motor and cognitive functions. PD typically has a unilateral symptom onset. People with PD may develop greater left-side of the body motor symptom severity (LPD) or right-side of the body motor symptom severity (RPD). From these unilateral motor deficits, we infer contralateral brain pathology. Hemispheric asymmetry in the pathology of LPD or RPD subgroups may lead to different cognitive deficits within each group, including impairments in response inhibition, switching, language processing and social cognitive abilities. However, the relationship between motor symptom asymmetry and cognitive impairments remains understudied. Thus, we compared the cognitive abilities of people with LPD versus RPD. A novel therapeutic intervention aimed at simultaneously addressing motor and cognitive impairments in PD is also explored.;Results: In Study 1, LPD participants were significantly slower to complete the Color Word inhibition task and the Trail Making task compared to RPD participants and Controls. In Study 2, LPD participants were also significantly more impaired on prosody emotion recognition tasks compared to RPD participants and Controls. Finally, in Study 3, PD participants who completed dance movement training (DMT) showed improved motor performance such as increased ability to balance and reduced risk of falling, as well as improved cognitive performance such as increased switching ability and creativity. They also reported significantly increased satisfaction in activities of daily living. PD participants who did not receive the DMT intervention did not show any of these changes.;Conclusions: Findings from Studies 1 & 2 suggest that left and right motor symptom onset results in different patterns of cognitive dysfunction. LPD participants showed deficits in cognitive abilities including response inhibition, switching and emotion recognition and may be at greater risk for cognitive dysfunction than RPD participants. Findings from Study 3 indicate that dance movement training is an effective form of therapy for people with PD who experience motor, cognitive and quality of life impairments.