Objective: Explore how cholinergic activity (measured by short latency afferent inhibition [SAI]) and attention relate to quality of turning performance over a week of daily life in people with Parkinson’s disease (PD).

Background: Turning is a complex measure of functional mobility that may require cognitive resources for optimal performance. Difficulty turning while walking is an early sign in PD leading to reduced mobility and increased risk of falls. Although dopaminergic therapy is effective for many motor impairments, the effect is limited for a number of measures of balance and gait, including turning. This evidence suggests the involvement of non-dopaminergic systems in complex mobility function, with increasing evidence that the cholinergic system plays a key role.

Method: So far, 6 healthy older adults and 5 people with PD have been recruited. Cholinergic activity was assessed using the transcranial magnetic stimulation technique of SAI while ‘on’ levodopa. Attention was measured using a simple reaction time (SRT) and choice reaction time (CRT) battery. Turning during gait was assessed in the home and community environment over 7 days with participants wearing a body-worn inertial sensor at the fifth lumbar vertebrae. Turning characteristics were averaged over seven days to assess the average number of turns per half hour as well as average turn duration and peak turn velocity.

Results: Preliminary results suggest poorer cholinergic activity in people with PD (SAI; 90%) compared to older adults (SAI; 77%), but this did not reach significance (Z=-1.5, p=0.14). In addition, people with PD demonstrated significantly poorer attention (CRT, Z=-2.2, p=0.03). Furthermore, people with PD demonstrated significantly poorer quantity and quality of turning in daily life (reduced number of turns, slower turn velocity and longer turn duration). Across both groups there was a significant relationship between poorer attention and increased average turn angle (rho=-.73, p=0.01) but no relationship between SAI and turning.

Conclusion: These preliminary findings suggest that cholinergic activity, attention and turning are often poorer in PD than healthy older adults. Poorer cholinergic function and attention therefore may relate to turning ability in PD. The mediating effects of cholinergic activity on attention and quality of turning needs to be determined in a larger cohort.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-interplay-between-cholinergic-activity-attention-and-turning-in-parkinsons-disease/