Background & Aims
Most studies investigating EEG power bands as biomarkers of neuropathic pain have reported associations between increased theta power and pain, while the relationship between pain and alpha and beta power have been more controversial. The aim of this study was to assess whether or not changes in widespread pain from Gulf War Illness (GWI) are associated with changes in EEG resting state theta, alpha, and beta power bands after one month on the low glutamate diet.
Methods
An ongoing clinical trial is recruiting Gulf War veterans who have symptoms consistent with Gulf War Illness (GWI), a chronic multisymptom condition characterized by widespread chronic pain, fatigue, cognitive dysfunction, sleep issues, mood dysregulation, and gastrointestinal symptoms. Preliminary analysis was conducted on data from 26 participants with significant pain who have completed their participation. Measures were collected at baseline and after one month on the low glutamate diet. Widespread pain was measured using tenderpoint exam and dolorimetry (averaging across 18 tenderpoint sites). Brain wave activity was measured using electroencephalography (EEG). Resting state EEG was recorded, 5 minutes with eyes closed and 5-minutes eyes open. Paired t-tests were used to compare pre-diet and post-diet measures and correlations were run to compare pain and EEG theta, alpha, and beta power band change scores after 1-month on the diet. Analyses were computed using R studio; significance defined as p<0.05.
Results
After one month on the low glutamate diet, significant reductions were observed in both myalgic score (p < 0.001) and the number of tenderpoints (p < 0.001), and the average pain threshold increased (p < 0.001) as measured by dolorimetry. Reduction in the number of tender points was positively correlated with reductions in posterior (p = 0.008), and global (p = 0.03) relative theta power with eyes open, and between total myalgic score and posterior relative theta power with eyes open (p = 0.02). Similarly, relative alpha power with eyes open was also positively correlated with total myalgic score in posterior regions (p = 0.02). The reduced number of tender points was also correlated with reductions in frontal (p = 0.01), central (p = 0.03), and global (p = 0.03) relative beta power with eyes closed. Changes in pain threshold were not correlated with changes in these brain waves.
Conclusions
This preliminary analysis on 26 participants is consistent with our previous findings showing that the low glutamate diet reduces pain. This reduction in pain was correlated with reductions in theta, alpha, and beta relative power, which is partially consistent with prior literature examining EEG as a biomarker for pain.
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