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Zack Y. Shan

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2 papers

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YNICL Journal 2018 Journal Article

Brain function characteristics of chronic fatigue syndrome: A task fMRI study

Zack Y. Shan
Kevin Finegan
Sandeep Bhuta
Timothy Ireland
Donald R. Staines
Sonya M. Marshall-Gradisnik
Leighton R. Barnden

The mechanism underlying neurological dysfunction in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is yet to be established. This study investigated the temporal complexity of blood oxygenation level dependent (BOLD) changes in response to the Stroop task in CFS patients. 43 CFS patients (47. 4 ± 11. 8 yrs) and 26 normal controls (NCs, 43. 4 ± 13. 9 yrs) were included in this study. Their mental component summary (MCS) and physical component summary (PCS) from the 36-item Short Form Health Survey (SF-36) questionnaire were recorded. Their Stroop colour-word task performance was measured by accuracy and response time (RT). The BOLD changes associated with the Stroop task were evaluated using a 2-level general linear model approach. The temporal complexity of the BOLD responses, a measure of information capacity and thus adaptability to a challenging environment, in each activated region was measured by sample entropy (SampEn). The CFS patients showed significantly longer RTs than the NCs (P < 0. 05) but no significant difference in accuracy. One sample t-tests for the two groups (Family wise error adjusted PFWE < 0. 05) showed more BOLD activation regions in the CFS, although a two sample group comparison did not show significant difference. BOLD SampEns in ten regions were significantly lower (FDR-q < 0. 05) in CFS patients. BOLD SampEns in 15 regions were significantly associated with PCS (FDR-q < 0. 05) and in 9 regions were associated with MCS (FDR-q < 0. 05) across all subjects. SampEn of the BOLD signal in the medioventral occipital cortex could explain 40% and 31% of the variance in the SF-36 PCS and MCS scores, and those in the precentral gyrus could explain an additional 16% and 7% across all subjects. This is the first study to investigate BOLD signal SampEn in response to tasks in CFS. The results suggest the brain responds differently to a cognitive challenge in patients with CFS, with recruitment of wider regions to compensate for lower information capacity.

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YNICL Journal 2018 Journal Article

Hyperintense sensorimotor T1 spin echo MRI is associated with brainstem abnormality in chronic fatigue syndrome

Leighton R. Barnden
Zack Y. Shan
Donald R. Staines
Sonya Marshall-Gradisnik
Kevin Finegan
Timothy Ireland
Sandeep Bhuta

We recruited 43 Chronic Fatigue Syndrome (CFS) subjects who met Fukuda criteria and 27 healthy controls and performed 3T MRI T1 and T2 weighted spin-echo (T1wSE and T2wSE) scans. T1wSE signal follows T1 relaxation rate (1/T1 relaxation time) and responds to myelin and iron (ferritin) concentrations. We performed MRI signal level group comparisons with SPM12. Spatial normalization after segmentation was performed using T2wSE scans and applied to the coregistered T1wSE scans. After global signal-level normalization of individual scans, the T1wSE group comparison detected decreased signal-levels in CFS in a brainstem region (cluster-based inference controlled for family wise error rate, P FWE = 0. 002), and increased signal-levels in large bilateral clusters in sensorimotor cortex white matter (cluster P FWE < 0. 0001). Moreover, the brainstem T1wSE values were negatively correlated with the sensorimotor values for both CFS (R 2 = 0. 31, P = 0. 00007) and healthy controls (R 2 = 0. 34, P = 0. 0009), and the regressions were co-linear. This relationship, previously unreported in either healthy controls or CFS, in view of known thalamic projection-fibre plasticity, suggests brainstem conduction deficits in CFS may stimulate the upregulation of myelin in the sensorimotor cortex to maintain brainstem – sensorimotor connectivity. VBM did not find group differences in regional grey matter or white matter volumes. We argued that increased T1wSE observed in sensorimotor WM in CFS indicates increased myelination which is a regulatory response to deficits in the brainstem although the causality cannot be tested in this study. Altered brainstem myelin may have broad consequences for cerebral function and should be a focus of future research.

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