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ObjectiveThis study aimed to explore whether olfactory response can be a sign of consciousness and represent higher cognitive processing in patients with disorders of consciousness (DoC) using clinical and electroencephalogram data.MethodsTwenty-eight patients with DoC [13 vegetative states (VS)/unresponsive wakefulness syndrome (UWS) and 15 minimally conscious states (MCS)] were divided into two groups: the presence of olfactory response (ORES) group and the absence of olfactory response (N-ORES) group according to behavioral signs from different odors, i.e., vanillin, decanoic acid, and blank stimuli. We recorded an olfactory task-related electroencephalogram (EEG) and analyzed the relative power and functional connectivity at the whole-brain level in patients with DoC and healthy controls (HCs). After three months, the outcomes of DoC patients were followed up using the coma recovery scale-revised (CRS-R).ResultsA significant relationship was found between olfactory responses and the level of consciousness (χ2(1) = 6.892, p = 0.020). For olfactory EEG, N-ORES patients showed higher theta functional connectivity than ORES patients after stimulation with vanillin (p = 0.029; p = 0.027). Patients with N-ORES showed lower alpha and beta relative powers than HCs at the group level (p = 0.019; p = 0.033). After three months, 62.5% (10/16) of the ORES patients recovered consciousness compared to 16.7% (2/12) in the N-ORES group. The presence of olfactory response was significantly associated with an improvement in consciousness (χ2(1) = 5.882, p = 0.023).ConclusionOlfactory responses should be considered signs of consciousness. The differences in olfactory processing between DoC patients with and without olfactory responses may be a way to explore the neural correlates of olfactory consciousness in these patients. The olfactory response may help in the assessment of consciousness and may contribute to therapeutic orientation.

Background Repetitive transcranial magnetic stimulation (rTMS), as a non-invasive brain stimulation technique, has shown potentials for consciousness recovery of patients with disorders of consciousness (DoC), as, to a certain extent, it is effective in regulating the excitability of central nervous system. However, it is difficult to achieve satisfactory effect with “one size fits all” rTMS treatment due to different clinical conditions of patients. There is an urgent need to develop individualized strategy to improve the effectiveness of rTMS on patients with DoC. Methods Our protocol is a randomized double-blind sham-controlled crossover trial that includes 30 DoC patients. Each patient will received 20 sessions, in which 10 sessions will be rTMS-active stimulus, and the other 10 sessions will be sham stimulus, separated by no less than 10 days’ washout period. The rTMS-active will include 10 Hz rTMS over the individualized-targeted selection area for each patient according to the different insult regions of the brain. Coma Recovery Scale-Revised (CRS-R) will be used as primary outcome at baseline, after the first stage of stimulation, at the end of the washout period, and after the second stage of stimulation. Secondary outcomes will be measured at the same time, including efficiency, relative spectral power, and functional connectivity of high-density electroencephalograph (EEG). Adverse events will be recorded during the study. Discussion rTMS has obtained grade A evidence in treating patients with several central nervous system diseases, and there has been some evidence showing partial improvement on level of consciousness in DoC patients. However, the effectiveness of rTMS in DoC is only 30~36%, mostly due to the non-specific target selection. In this protocol, we present a double-blind crossover randomized sham-controlled trial based on the individualized-targeted selection strategy that aims to study the effectiveness of rTMS therapy for DoC, and the result may provide new insights to non-invasive brain stimulation. Trial registration ClinicalTrials.gov: NCT05187000. Registered on January 10, 2022.

ObjectiveWhen regaining consciousness, patients who emerge from a minimally conscious state (EMCS) present with different levels of functional disability, which pose great challenges for treatment. This study investigated the frontoparietal activity in EMCS patients and its effects on functional disability.Materials and methodsIn this preliminary study, 12 EMCS patients and 12 healthy controls were recruited. We recorded a resting-state scalp electroencephalogram (EEG) for at least 5 min for each participant. Each patient was assessed using the disability rating scale (DRS) to determine the level of functional disability. We analyzed the EEG power spectral density and sensor-level functional connectivity in relation to the patient’s functional disability.ResultsIn the frontoparietal region, EMCS patients demonstrated lower relative beta power (P < 0.01) and higher weighted phase lag index (wPLI) values in the theta (P < 0.01) and gamma (P < 0.01) bands than healthy controls. The frontoparietal theta wPLI values of EMCS patients were positively correlated with the DRS scores (rs = 0.629, P = 0.029). At the whole-brain level, EMCS patients only had higher wPLI values in the theta band (P < 0.01) than healthy controls. The whole-brain theta wPLI values of EMCS patients were also positively correlated with the DRS scores (rs = 0.650, P = 0.022). No significant difference in the power and connectivity between the frontoparietal region and the whole brain in EMCS patients was observed.ConclusionEMCS patients still experience neural dysfunction, especially in the frontoparietal region. However, the theta connectivity in the frontoparietal region did not increase specifically. At the level of the whole brain, the same shift could also be seen. Theta functional connectivity in the whole brain may underlie different levels of functional disability.

Background Microbiome-gut-brain axis may be involved in the progression of age-related cognitive impairment and relevant brain structure changes, but evidence from large human cohorts is lacking. This study was aimed to investigate the associations of gut microbiome with cognitive impairment and brain structure based on multi-omics from three independent populations. Methods We included 1430 participants from the Guangzhou Nutrition and Health Study (GNHS) with both gut microbiome and cognitive assessment data available as a discovery cohort, of whom 272 individuals provided fecal samples twice before cognitive assessment. We selected 208 individuals with baseline microbiome data for brain magnetic resonance imaging during the follow-up visit. Fecal 16S rRNA and shotgun metagenomic sequencing, targeted serum metabolomics, and cytokine measurements were performed in the GNHS. The validation analyses were conducted in an Alzheimer’s disease case–control study (replication study 1, n = 90) and another community-based cohort (replication study 2, n = 1300) with cross-sectional dataset. Results We found protective associations of specific gut microbial genera (Odoribacter, Butyricimonas, and Bacteroides) with cognitive impairment in both the discovery cohort and the replication study 1. Result of Bacteroides was further validated in the replication study 2. Odoribacter was positively associated with hippocampal volume (β, 0.16; 95% CI 0.06–0.26, P = 0.002), which might be mediated by acetic acids. Increased intra-individual alterations in gut microbial composition were found in participants with cognitive impairment. We also identified several serum metabolites and inflammation-associated metagenomic species and pathways linked to impaired cognition. Conclusions Our findings reveal that specific gut microbial features are closely associated with cognitive impairment and decreased hippocampal volume, which may play an important role in dementia development.

Background: Repetitive transcranial magnetic stimulation (rTMS), as a non-invasive brain stimulation technique, has shown potentials for consciousness recovery of patients with disorders of consciousness (DoC), as it is effective in regulating the excitability of central nervous system. However it is difficult to achieve satisfactory effect with “one size fits all” rTMS treatment due to different clinical conditions of patients. There is an urgent need to develop individualized strategy to improve the effectiveness rTMS on patients with DoC.Methods: Our protocol is a randomized double-blind sham-controlled crossover trial that includes 30 DoC patients. Each patient will received 20 sessions, in which 10 sessions will be rTMS-active stimulus and the other 10 sessions will be sham stimulus, separated by no less than 10 days’ washout period. The rTMS-active will include 10 Hz rTMS over the individualized-targeted selection area for each patient according to the different insult regions of the brain. Coma Recovery Scale-Revised (CRS-R) will be used as primary outcome at baseline, after the first stage of stimulation, at the end of the washout period and after the second stage of stimulation. Secondary outcomes will be measured at the same time, including efficiency, relative spectral power and functional connectivity of high-density electroencephalo-graph (EEG). Adverse events will be recorded during the study.Discussion: rTMS has obtained Grade A evidence in treating patients with several central nervous system diseases, and there has been some evidence showing partial improvement on level of consciousness in DoC patients. However, the effectiveness of rTMS in DoC is only 30%~36%, mostly due to the non-specific target selection. In this protocol, we present a double-blind crossover randomized sham-controlled trial based on the individualized-targeted selection strategy that aims to study the effectiveness of rTMS therapy for DoC, and the result may provide new insights to non-invasive brain stimulation.Trial registration: ClinicalTrials.gov: NCT05187000. Registered on January 10, 2022.

Emerging studies have demonstrated that interleukin (IL)-33 and its receptor ST2 act as key factors in inflammatory diseases. Moreover, accumulating evidence has suggested that cytokines, including tumor necrosis factor (TNF)-α and IL-1β, trigger an inflammatory cascade. SIRT1 has been shown to suppress the expression of inflammatory cytokines. However, the effects of SIRT1 on IL-33/ST2 signaling and initiation of the inflammatory cascade via modulation of TNF-α and IL-1β by IL-33 remain unclear. In the present study, we found that the dorsal root ganglion (DRG) IL-33 and ST2 were upregulated in a rat model of spared nerve injury (SNI) and intrathecal injection of either IL-33 or ST2 antibodies alleviated mechanical allodynia and downregulated TNF-α and IL-1β induced by SNI. In addition, activation of SIRT1 decreased enhanced DRG IL-33/ST2 signaling in SNI rats. Artificial inactivation of SIRT1 via intrathecal injection of an SIRT1 antagonist could induce mechanical allodynia and upregulate IL-33 and ST2. These results demonstrated that reduction in SIRT1 could induce upregulation of DRG IL-33 and ST2 and contribute to mechanical allodynia induced by SNI in rats.

The innate immune response, which is tightly regulated by Toll-like receptor 4 (TLR4) pathway, has been shown to play a critical role in brain damage following cerebral ischemia-reperfusion injury. Hydroxysafflor yellow A (HSYA) is the active component extracted from the Flos Carthami and has been reported to decrease neurological deficit scores following ischemia-reperfusion injury. However, the precise mechanism by which it exerts these neuroprotective effects remains poorly understood. In this study, we demonstrated that the administration of HSYA could significantly down-regulate TLR4 expression in middle cerebral artery occlusion (MCAO) mice. Following the down-regulation of TLR4 by HSYA treatment, cerebral infarction and inflammatory neuronal damage was alleviated. The number of apoptotic neurons in the HSYA-treated group was significantly decreased along with the decrease in TLR4 expression in MCAO mice. Activation of the NF-κB and MAPK signaling pathways was observed at 1h following ischemia and at 24h post-reperfusion. HSYA could significantly inhibit NF-κB p-p65, ERE1/2, JNK and p38 phosphorylation, which coincided with the suppressed secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and nitric oxide (NO). Moreover, brain-derived neurotrophic factor (BDNF) was up-regulated following 1h of ischemia and continued to increase initially during reperfusion but was down-regulated at later stages. Following treatment with HSYA, BDNF was up-regulated relative to control MCAO mice at 1h post-ischemia and at 12 and 24h post-reperfusion. Our data suggest that HSYA exerts neurotrophic and anti-inflammatory functions against ischemic stroke by inhibiting TLR4 pathway-mediated signaling responses.

Previous studies have shown that men and women behave differently on diverse cognitive tasks. However, gender differences in recognizing and memorizing faces when in emotional conflict situations are unknown. Therefore, a face-word Stroop task (emotional conflict) and subsequent memory task were used in the present study to examine gender differences among young adults in an emotional conflict situation. Behavioural data showed that men were better able to recognize faces while in emotional conflict, whereas women performed better at the memorization task. Emotional conflict had different effects on memorization performance between men and women. Women memorized more incongruent faces and men more congruent ones. The results confirm the need for further neural study in this area.