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2 results

  • Short-Latency Afferent Inhibition Correlates with Stage of Disease in Parkinson’s Patients

  • Supriyo Choudhury, Ummatul Siddique, Simin Rahman, Yogesh Kumar, Sattwika Banerjee, Mark R. Baker, Stuart N. Baker, Hrishikesh Kumar
  • Journal:
    Canadian Journal of Neurological Sciences / Volume 50 / Issue 4 / July 2023
    Published online by Cambridge University Press:
    10 June 2022, pp. 579-583
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  • Background:

    Sensory-motor decoupling at the cortical level involving cholinergic circuitry has also been reported in Parkinson’s Disease (PD). Short-latency afferent inhibition (SAI) is a transcranial magnetic stimulation (TMS) paradigm that has been used previously to probe cortical cholinergic circuits in well-characterised subgroups of patients with PD. In the current study, we compared SAI in a cohort of PD patients at various stages of disease and explored correlations between SAI and various clinical measures of disease severity.

    Methods:

    The modified Hoehn and Yahr (H&Y) scale was used to stage disease in 22 patients with PD. Motor and cognitive function were assessed using the MDS-UPDRS (Movement Disorder Society-sponsored revision of the Unified Parkinson’s Disease Rating Scale) part III and MoCA (Montreal Cognitive Assessment) score, respectively. Objective gait assessment was performed using an electronic walkway (GAITRite®). SAI was measured as the average percentage inhibition of test motor-evoked potentials (MEPs) conditioned by electrical stimulation of the contralateral median nerve at the wrist.

    Results:

    SAI was significantly reduced in patients with advanced PD (H&Y stage 3) compared to early PD patients (H&Y stage 1) on pairwise comparison. The visuospatial executive function and orientation domains of cognition demonstrated significant negative associations with SAI.

    Conclusion:

    Cortical sensory-motor integration is progressively diminished as disease progresses. The observation that a reduction in SAI is associated with a reduction in cognitive function possibly reflects the progressive involvement of cortical cholinergic circuits in PD with increasing motor stage. Future longitudinal studies are necessary to confirm this preliminary result.

  • Age Differences in Reaction Times and a Neurophysiological Marker of Cholinergic Activity

  • Marielle Young-Bernier, Annick N. Tanguay, François Tremblay, Patrick S. R. Davidson
  • Journal:
    Canadian Journal on Aging / La Revue canadienne du vieillissement / Volume 34 / Issue 4 / December 2015
    Published online by Cambridge University Press:
    02 November 2015, pp. 471-480

  • The deterioration of the cholinergic system in aging is hypothesized to contribute to age-related declines in attention. We investigated potential age differences in performance on the Attention Network Test (ANT) and intra-individual variability in speed (RT-IIV) on go/no-go and choice reaction time tasks in young and healthy older adults. We also asked whether short-latency afferent inhibition (SAI), a neurophysiological marker of central cholinergic activity obtained via transcranial magnetic stimulation, might be correlated with performance. Older adults were slower on the ANT and exhibited greater RT-IIV than young adults on the multiple choice RT task, but there were no age differences on the ANT network scores (alerting, orienting, and executive control). SAI was diminished in older adults, but it was not significantly correlated with performance. It may only be in cases of severe cholinergic dysfunction that relations with attention emerge. Other brain mechanisms may also be stronger predictors of functions relating to attention.