Two sides of the same coin: Impairment in perception of temporal components of rhythm and cognitive functions in Parkinson’s disease

• Impairment in perception of various temporal components of rhythm viz., rhythm discrimination, rhythmic contour, meter and beat in musical context and cognitive functions viz., attention, immediate memory, verbal and visual working memory tests of was assessed in patients with Parkinson’s disease (PD) and compared with age, gender and education matched healthy participants (HC).
• PD performed poorly on tests assessing the perception of various components of rhythm as well as cognitive functions compared to HC. There was significant correlation between cognitive functions and various components of rhythm perception.
• Step wise linear regression analysis showed that verbal working memory with higher task difficulty and focused attention predicted the performance on the various components of rhythm perception.
• Step wise linear regression analysis also showed that beat based rhythm discrimination predicted the performance on verbal working memory and focussed attention, beat perception in musical context predicted the performance on visual working memory.
• It may be hypothesized from the findings on the present study that rhythm based intervention that targets motor, gait functions may also benefit improvement in cognitive functions and perhaps vice-versa, which are known to be impaired in PD.

BackgroundPatients with Parkinson’s disease (PD) have motor dysfunction, cognitive dysfunction, impairment in temporal processing and rhythm discrimination. Apart from beat-based rhythm discrimination, perception of other temporal components of rhythm such as meter, contour and beat perception in musical context has not been studied hitherto. So far relation between cognitive functions and perception and discrimination of temporal components of rhythm has not been examined.MethodsPerformance of PD (n = 21) in comparison with matched healthy-controls (HC) on beat-discrimination, rhythmic contour, meter perception and beat-perception in musical context and on cognitive tests measuring immediate memory, focussed attention, verbal and visual working memory in the non-musical domain was examinedResultsPD performed poorly on all the cognitive tests and rhythm tests compared to HC (p = <0.01). Verbal working memory, and focussed attention correlated significantly with rhythm perception. Step wise linear regression analysis showed that focussed attention and verbal working memory predicted the performance on the rhythm tests and beat discrimination, beat perception in musical context and discrimination of rhythmic contour predicted performance on the cognitive tests. Findings indicate that patients with PD have deficits in rhythm perception and discrimination and there is a close inter-relation between cognitive processes and perception and discrimination of various temporal components of rhythm.ConclusionsCognitive functions are closely linked with rhythm perception. Cognitive functions and rhythm perception predict the performance on the other. The findings also have implication on planning rhythm-based intervention and cognitive remediation that may have mutual benefits in both the domains.