Current advances in neurotrauma research: diagnosis, neuroprotection, and neurorepair

Escalation of Tau Accumulation after a Traumatic Brain Injury: Findings from Positron Emission Tomography

Traumatic brain injury (TBI) has come to be recognized as a risk factor for Alzheimer's disease (AD), with poorly understood underlying mechanisms. We hypothesized that a history of TBI would be associated with greater tau deposition in elders with high-risk for dementia. A Groups of 20 participants with self-reported history of TBI and 100 without any such history were scanned using [18F]-AV1451 positron emission tomography as part of the Alzheimer's Disease Neuroimaging Initiative (ADNI). Scans were stratified into four groups according to TBI history, and by clinical dementia rating scores into cognitively normal (CDR = 0) and those showing cognitive decline (CDR ≥ 0.5). We pursued voxel-based group comparison of [18F]-AV1451 uptake to identify the effect of TBI history on brain tau deposition, and for voxel-wise correlation analyses between [18F]-AV1451 uptake and different neuropsychological measures and cerebrospinal fluid (CSF) biomarkers. Compared to the TBI-/CDR ≥ 0.5 group, the TBI+/CDR ≥ 0.5 group showed increased tau deposition in the temporal pole, hippocampus, fusiform gyrus, and inferior and middle temporal gyri. Furthermore, the extent of tau deposition in the brain of those with TBI history positively correlated with the extent of cognitive decline, CSF-tau, and CSF-amyloid. This might suggest TBI to increase the risk for tauopathies and Alzheimer's disease later in life.

Dextromethorphan Attenuates Sensorineural Hearing Loss in an Animal Model and Population-Based Cohort Study

The effect of dextromethorphan (DXM) use in sensorineural hearing loss (SNHL) has not been fully examined. We conducted an animal model and nationwide retrospective matched-cohort study to explore the association between DXM use and SNHL. Eight-week-old CBA/CaJ hearing loss was induced by a white noise 118 dB sound pressure level for 3 h. DXM (30 mg/kg) was administered intraperitoneally for 5 days and boost once round window DXM socking. In population-based study, we examined the medical records over 40 years old in Taiwan’s National Health Insurance Research Database between 2000 and 2015 to establish retrospective matched-cohort to explore the correlation between DXM use and SNHL. Using click auditory brainstem response (ABR), hearing threshold was measured as 48.6 ± 2.9 dB in control mice compared with 42.6 ± 7.0 dB in DXM mice, which differed significantly (p = 0.002) on day 60 after noise exposure with a larger ABR wave I amplitude in DXM mice. In human study, we used a Cox regression hazard model to indicate that a significantly lower percentage individuals developed SNHL compared with and without DXM use (0.44%, 175/39,895 vs. 1.05%, 1675/159,580, p < 0.001). After adjustment for age and other variables [adjusted hazard ratio: 0.725 (95% confidence interval: 0.624–0.803, p < 0.001)], this study also demonstrated that DXM use appeared to reduce the risk of developing SNHL. This animal study demonstrated that DXM significantly attenuated noise-induced hearing loss. In human study, DXM use may have a protective effect against SNHL.

Сlass II histone deacetylases in the post-stroke recovery period-expression, cellular, and subcellular localization-promising targets for neuroprotection

Histone deacetylases (HDAC) inhibitors can protect nerve cells after a stroke, but it is unclear which HDAC isoform is involved in this effect. We studied cellular and intracellular rearrangement of class II HDACs at late periods after photothrombotic infarct (PTI) in the mouse sensorimotor cortex in the tissue surrounding the ischemia core and in the corresponding region of the contralateral hemisphere. We observed a decrease in HDAC4 in cortical neurons and an increase in its nuclear translocation. HDAC6 expression in neurons was also increased. Moreover, HDAC6-positive cells had elevated apoptosis. Tubostatin A (Tub A)-induced decrease in the activity of HDAC6 restored acetylation of α-tubulin during the early poststroke recovery period and reduced apoptosis of nerve cells thus protecting the brain tissue. Selective inhibition of HDAC6 elevated expression of growth-associated protein-43 (GAP43), which remained high up to 14 days after stroke and promoted axogenesis and recovery from the PTI-induced neurological deficit. Selective HDAC6 inhibitor Tub A markedly reduced neuronal death and increased acetylation of α-tubulin and the level of GAP43. Thus, HDAC6 inhibition could be a promising strategy for modulation of brain recovery as it can increase the intensity and reduce the duration of reparation processes in the brain after stroke.

Neurocircuitry of acupuncture effect on cognitive improvement in patients with mild cognitive impairment using magnetic resonance imaging: a study protocol for a randomized controlled trial

Background

Mild cognitive impairment (MCI) is defined as a decline in cognitive state with preservation of activities of daily living. Medications such as donepezil and rivastigmine have been commonly prescribed for MCI, but their use is controversial. Acupuncture has been widely used in Korea and has been shown to improve cognitive function. The aim of this study is to evaluate the efficacy of acupuncture for MCI and investigate the effect of acupuncture on structural and functional brain changes in patients with MCI.

Methods

This study is a randomized, assessor-blinded, sham-controlled trial. Fifty participants with MCI will be randomly assigned to the acupuncture group (n = 25) or sham acupuncture group (n = 25). The acupuncture group will receive acupuncture treatment at nine acupuncture points (GV20, EX-HN1, bilateral LI4, and ST36) twice a week for 12 weeks. The sham acupuncture group will receive sham acupuncture treatment at the same points with non-penetrating sham needles. Both groups will be restricted from all other treatments for the improvement of cognitive function. The primary outcome measure is the Digit Span Test (DST). The secondary outcome measures are the Digit Symbol Substitution Test (DSST), Korean version of Montreal Cognitive Assessment (MoCA-K), Seoul Neuropsychological Screening Battery-II (SNSB-II), Beck Depression Inventory-II (BDI-II), State-Trait Anxiety Inventory (STAI), working memory (WM) task performance score, and structural/functional brain changes. Outcomes will be assessed at screening, baseline, 4 and 8 weeks, and after the end of treatment. We will also observe adverse events. In the statistical analysis, a full analysis set and per-protocol analysis will be performed.

Discussion

This randomized clinical trial aims to examine the efficacy of acupuncture treatment for MCI. Neuropsychological tests, psychological inventories for measuring depression and anxiety, and magnetic resonance imaging will be performed to investigate the underlying neurological mechanisms and the association between cognition, emotion, and brain networks following acupuncture treatment. The results of the trial will provide evidence supporting the efficacy of acupuncture and also add to the neurobiological understanding of acupuncture treatment for MCI.

Trial registration

Clinical Research Information Service, KCT0002896. Registered on 25 May 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3446-9) contains supplementary material, which is available to authorized users.

Dextromethorphan: An update on its utility for neurological and neuropsychiatric disorders

Dextromethorphan (DM) is a commonly used antitussive and is currently the only FDA-approved pharmaceutical treatment for pseudobulbar affect. Its safety profile and diverse pharmacologic actions in the central nervous system have stimulated new interest for repurposing it. Numerous preclinical investigations and many open-label or blinded clinical studies have demonstrated its beneficial effects across a variety of neurological and psychiatric disorders. However, the optimal dose and safety of chronic dosing are not fully known. This review summarizes the preclinical and clinical effects of DM and its putative mechanisms of action, focusing on depression, stroke, traumatic brain injury, seizure, pain, methotrexate neurotoxicity, Parkinson's disease and autism. Moreover, we offer suggestions for future research with DM to advance the treatment for these and other neurological and psychiatric disorders.

Neuroprotective Effects of Electroacupuncture on an Animal Model of Bilateral Common Carotid Artery Occlusion

Mild cognitive impairment (MCI) is considered as an intermediate zone between normal aging and dementia. The most prominent feature of MCI is an isolated mild decline in memory, whereas other cognitive functions remain intact. The symptoms of vascular cognitive impairment (VCI) range from MCI to dementia, and an animal model of VCI has been established in a gerbil by transient bilateral common carotid artery occlusion (BCCAO). In the current study, we set out to investigate whether electroacupuncture (EA) could improve memory in gerbils with BCCAO-induced MCI. Animals were randomly divided into two groups: sham-operated group (n = 17) and a model group that was subdivided into BCCAO, n = 17, and EA-treated BCCAO, n = 28. Gerbils were treated with EA at KI3 or GV20 four times every other day using a set of electrical stimulus pulses (1 mA, 2 Hz) that were applied for 20 min. For investigation of cognitive function, we performed a Y-maze test and Western blotting to identify the expression of neuroinflammatory proteins. EA treatment at KI3 ("Taegye" acupoint) improved cognitive function and reduced the expression of neuroinflammatory proteins including ionized calcium-binding adaptor molecule 1, toll-like receptor 4, tumor necrosis factor alpha, and phospho-extracellular signal-regulated kinase in the hippocampus of gerbils that had undergone BCCAO. Furthermore, using micro-positron emission tomography/computed tomography, we demonstrated that EA treatment increased glucose metabolism in the hippocampus of these animals. The present study highlights the neuroprotective effect of EA treatment against BCCAO-induced memory dysfunction, neuroinflammation, and glucose metabolism. Our findings suggest that EA, which has previously been used in complementary and alternative medicine, might also be considered as a therapy that can improve memory and reduce neuroinflammation associated with dementia.