Objective: To investigate the hypothesis that altered ‘top down’ processing contributes to the development of pain in Parkinson’s disease (PD).

Background: Altered ‘top down’ processing of pain characterises several chronic pain conditions and occurs when the cortex modifies the incoming pain signal as it reaches the brain [1]. This contrasts with ‘bottom up’ enhancement of pain whereby the pain signal is amplified on its way up to the brain. Chronic pain is common in people with PD, and is often considered to be caused by the motor impairments associated with the disease. Although several studies have demonstrated altered ‘bottom up’ pain processing in PD, the contribution of enhanced pain anticipation and enhanced ‘top down’ processing of pain has not been fully explored.

Methods: In the present study, EEG was recorded whilst noxious stimuli was delivered by a carbon dioxide laser to the forearm. Prior to the noxious stimuli, a visual cue and a three second auditory countdown was delivered to investigate anticipation of the stimuli. Participants with PD were compared with a Healthy Control (HC) group.

Results: EEG source localisation reported an increased activation in the mid and posterior cingulate cortex in the PD group compared to the HC group during late anticipation, indicating enhanced cortical activity before the pain signal. Subsequently, the PD group was more sensitive to the laser and required a lower energy level to induce pain.

Conclusions: The cingulate cortex is associated with the emotional processing of pain. Previous studies have demonstrated that anticipation correlates with the subsequent pain perceived via ‘top down mechanisms’ [1]. This study therefore provides evidence supporting the hypothesis that enhanced ‘top down’ processing of pain contributes to the development of chronic pain in PD.

References: 1. Brown, C.A., W. El-Deredy, and A.K.P. Jones, When the brain expects pain: common neural responses to pain anticipation are related to clinical pain and distress in fibromyalgia and osteoarthritis. Eur J Neurosci, 2013.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/enhanced-cingulate-activity-while-anticipating-pain-evidence-for-altered-top-down-processing-of-pain-in-pd/