Vitamin D deficiency may exacerbate adverse neurocognitive outcomes in the progression of diseases such as Parkinson's, Alzheimer's, and other dementias. Mild cognitive impairment (MCI) is prodromal ...for these neurocognitive disorders and neuroimaging studies suggest that, in the elderly, this cognitive impairment is associated with a reduction in hippocampal volume and white matter structural integrity. To test whether vitamin D is associated with neuroanatomical correlates of MCI, we analyzed an existing structural and diffusion MRI dataset of elderly patients with MCI. Based on serum 25‐OHD levels, patients were categorized into serum 25‐OHD deficient (<12 ng/mL, n = 27) or not‐deficient (>12 ng/mL, n = 29). Freesurfer 6.0 was used to parcellate the whole brain into 164 structures and segment the hippocampal subfields. Whole‐brain structural connectomes were generated using probabilistic tractography with MRtrix. The network‐based statistic (NBS) was used to identify subnetworks of connections that significantly differed between the groups. We found a significant reduction in total hippocampal volume in the serum 25‐OHD deficient group especially in the CA1, molecular layer, dentate gyrus, and fimbria. We observed a connection deficit in 13 regions with the right hippocampus at the center of the disrupted network. Our results demonstrate that low vitamin D is associated with reduced volumes of hippocampal subfields and connection deficits in elderly people with MCI, which may exacerbate neurocognitive outcomes. Longitudinal studies are now required to determine if vitamin D can serve as a biomarker for Alzheimer's disease and if intervention can prevent the progression from MCI to major cognitive disorders.
Emerging evidence suggests that the excessive accumulation of iron in subcortical and deep gray matter has been related to dementia. However, the presence and pattern of iron accumulation in vascular ...dementia (VaD) and Alzheimer's disease (AD) are rarely investigated.
To examine and compare the pattern and presence of brain iron accumulation of VaD and AD using quantitative susceptibility mapping (QSM).
Twelve patients with VaD, 27 patients with AD, and 18 control subjects were recruited in this institutional review-board approved study. Susceptibility maps were reconstructed from a three-dimensional multiecho spoiled gradient-echo sequence. Four regions of interest were drawn manually on QSM images, namely the globus pallidus, putamen, caudate nucleus, and pulvinar nucleus of the thalamus. Comparisons of patient demographics, and iron concentrations among the VaD, AD, and control subjects were assessed using analysis of variance and post-hoc analyses. The relationships of age and cognitive state with susceptibility values were assessed using partial correlation analysis.
In VaD and AD, overall susceptibility values were higher than those of control subjects. A significant difference in susceptibility values was found in the putamen and caudate nucleus (p < 0.001 and p = 0.002, respectively). However, susceptibility values did not differ between VaD and AD. Age and cognitive deficit severity were not related to susceptibility values in the VaD and AD groups.
Increased iron deposition in the putamen and caudate nucleus in VaD and AD patients was not associated with age or the severity of cognitive deficits. Further evaluations are needed to determine the temporal changes in iron load and their diagnostic role in dementia pathology.
Air pollution has become one of the most serious issues for human health and has been shown to be particularly concerning for neural and cognitive health. Recent studies suggest that fine particulate ...matter of less than 2.5 (PM2.5), common in air pollution, can reach the brain, potentially resulting in the development and acceleration of various neurological disorders including Alzheimer's disease, Parkinson's disease, and other forms of dementia, but the underlying pathological mechanisms are not clear. Astaxanthin is a red-colored phytonutrient carotenoid that has been known for anti-inflammatory and neuroprotective effects. In this study, we demonstrated that exposure to PM2.5 increases the neuroinflammation, the expression of proinflammatory M1, and disease-associated microglia (DAM) signature markers in microglial cells, and that treatment with astaxanthin can prevent the neurotoxic effects of this exposure through anti-inflammatory properties. Diesel particulate matter (Sigma-Aldrich) was used as a fine particulate matter 2.5 in the present study. Cultured rat glial cells and BV-2 microglial cells were treated with various concentrations of PM2.5, and then the expression of various inflammatory mediators and signaling pathways were measured using qRT-PCR and Western blot. Astaxanthin was then added and assayed as above to evaluate its effects on microglial changes, inflammation, and toxicity induced by PM2.5. PM2.5 increased the production of nitric oxide and reactive oxygen species and upregulated the transcription of various proinflammatory markers including Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Tumor necrosis factor α (TNFα), inducible nitric oxide synthase (iNOS), triggering receptor expressed on myeloid cells 2 (TREM2), Toll-like receptor 2/4 (TLR2/4), and cyclooxygenase-2 (COX-2) in BV-2 microglial cells. However, the mRNA expression of IL-10 and arginase-1 decreased following PM2.5 treatment. PM2.5 treatment increased c-Jun N-terminal kinases (JNK) phosphorylation and decreased Akt phosphorylation. Astaxanthin attenuated these PM2.5-induced responses, reducing transcription of the proinflammatory markers iNOS and heme oxygenase-1 (HO-1), which prevented neuronal cell death. Our results indicate that PM2.5 exposure reformulates microglia via proinflammatory M1 and DAM phenotype, leading to neurotoxicity, and the fact that astaxanthin treatment can prevent neurotoxicity by inhibiting transition to the proinflammatory M1 and DAM phenotypes. These results demonstrate that PM2.5 exposure can induce brain damage through the change of proinflammatory M1 and DAM signatures in the microglial cells, as well as the fact that astaxanthin can have a potential beneficial effect on PM2.5 exposure of the brain.
Autism spectrum disorder (ASD) is a pervasive developmental disorder characterized by three main behavioral symptoms including social deficits, impaired communication, and stereotyped and repetitive ...behaviors. ASD prevalence shows gender bias to male. Prenatal exposure to valproic acid (VPA), a drug used in epilepsy and bipolar disorder, induces autistic symptoms in both human and rodents. As we reported previously, prenatally VPA‐exposed animals at E12 showed impairment in social behavior without any overt reproductive toxicity. Social interactions were not significantly different between male and female rats in control condition. However, VPA‐exposed male offspring showed significantly impaired social interaction while female offspring showed only marginal deficits in social interaction. Similar male inclination was observed in hyperactivity behavior induced by VPA. In addition to the ASD‐like behavioral phenotype, prenatally VPA‐exposed rat offspring shows crooked tail phenotype, which was not different between male and female groups. Both male and female rat showed reduced GABAergic neuronal marker GAD and increased glutamatergic neuronal marker vGluT1 expression. Interestingly, despite of the similar increased expression of vGluT1, post‐synaptic marker proteins such as PSD‐95 and α‐CAMKII expression was significantly elevated only in male offspring. Electron microscopy showed increased number of post‐synapse in male but not in female at 4 weeks of age. These results might suggest that the altered glutamatergic neuronal differentiation leads to deranged post‐synaptic maturation only in male offspring prenatally exposed to VPA. Consistent with the increased post‐synaptic compartment, VPA‐exposed male rats showed higher sensitivity to electric shock than VPA‐exposed female rats. These results suggest that prenatally VPA‐exposed rats show the male preponderance of ASD‐like behaviors including defective social interaction similar to human autistic patients, which might be caused by ectopic increase in glutamatergic synapses in male rats.
Prenatal VPA exposure induces male inclined autistic symptoms including impaired social interactions and seizure susceptibility in rat fetus. These gender‐specific impairments of VPA‐exposed rats, which are similar to human autistic patients, may provide experimental models to elucidate the gender‐dependent symptoms and molecular mechanisms in anti‐social disorders including ASD, especially focusing on the development of excitatory/inhibitory nervous systems and synapses.
This study investigated the associations between exposure to ambient air pollutants and the incidence of osteoporosis using the Korean National Insurance Service-National Sample Cohort.
This ...nationwide, population-based, retrospective cohort study included 237,149 adults aged ≥40 years that did not have a diagnosis of osteoporosis at baseline between January 1, 2003, and December 31, 2015. Osteoporosis was defined as claim codes and prescriptions of bisphosphonates or selective estrogen receptor modulators at least twice annually. After matching values for PM
, NO
, CO, and SO
during the 2002-2015 time period and PM
in 2015 with residential areas, the incidence of osteoporosis was analyzed using a Cox proportional hazards regression model according to the quartile of average yearly concentrations of pollutants.
Overall 22.2% of the study subjects, 52,601 (male: 5.6%, female: 37.6%) adults in total, were newly diagnosed with osteoporosis and treated. Exposure to PM
was positively associated with incidence of osteoporosis (Q4: 1798 per 100,000 person-years vs. Q1: 1655 per 100,000 person-years). The adjusted hazard ratio (HR) with 95% confidence interval (CI) of Q4 in PM
was 1.034 (1.009-1.062). The effect of PM
on osteoporosis incidence was distinct in females (adjusted sub-HR: 1.065, 95% CI: 1.003-1.129), subjects aged < 65 years (adjusted sub-HR: 1.040, 95% CI: 1.010-1.072), and for residents in areas with low urbanization (adjusted sub-HR: 1.052, 95% CI: 1.019-1.087). However, there was no increase in osteoporosis based on exposure to NO
, CO, SO
, or PM
.
Long-term exposure to PM
was associated with newly diagnosed osteoporosis in Korean adults aged ≥40 years. This finding can aid in policy-making that is directed to control air pollution as a risk factor for bone health.
Cognitive decline is one of the most relevant signs of sarcopenia; however, it is challenging to perform tests for sarcopenia in patients with dementia. In a recent study, temporalis muscle thickness ...(TMT), an alternative to appendicular muscle mass (ASM), was found to be a valid index for screening sarcopenia. This study aimed to determine whether TMT correlates with ASM and evaluate the relationship between TMT and cognitive function in dementia patients. We recruited patients with a complaint of memory loss who visited the Memory Clinic of Konkuk University Medical Center between November 2014 and December 2020. Patients with probable Alzheimer’s disease (AD) without weakness were included. TMT was measured on axial T1-weighted magnetic resonance (MR) images, perpendicular to the long axis of the temporal muscle, at the orbital roof level. ASM was measured using body dual-energy X-ray absorptiometry (DXA). It was calculated as the sum of lean soft tissue mass in the arms and legs, and the value by ASM divided by height squared was used. Inter-rater reliability and intra-rater reliability were good and excellent, respectively. We found a correlation between TMT and skeletal ASM, which was obtained from cranial MR images and DXA, respectively (
r
= 0.379,
p
= 0.001). TMT was negatively correlated with age (
r
= − 0.296,
p
= 0.014) and positively correlated with body mass index (BMI) (
r
= 0.303,
p
= 0.012). Additionally, TMT was correlated with MMSE (
r
= 0.350,
p
= 0.003). After adjusting for educational years, there was still a correlation between TMT and MMSE (
r
= 0.256,
p
= 0.038). This study demonstrated that TMT correlates with ASM and cognitive function in patients with dementia. Measuring TMT using cranial MR images could help diagnose sarcopenia accessibly and assess cognitive function in patients with dementia.
Autism spectrum disorder (ASD) is a heterogeneously pervasive developmental disorder in which various genetic and environmental factors are believed to underlie its development. Recently, epigenetics ...has been suggested as a novel concept for ASD aetiology with a proposition that epigenetic marks can be transgenerationally inherited. Based on this assumption of epigenetics, we investigated the transgenerational inheritance of ASD-like behaviours and their related synaptic changes in the VPA animal model of ASD. The first generation (F1) VPA-exposed offspring exhibited autistic-like impaired sociability and increased marble burying. They also showed increased seizure susceptibility, hyperactivity and decreased anxiety. We mated the VPA-exposed F1 male offspring with naïve females to produce the second generation (F2), and then similarly mated the F2 to deliver the third generation (F3). Remarkably, the autism-like behavioural phenotypes found in F1 persisted to the F2 and F3. Additionally, the frontal cortices of F1 and F3 showed some imbalanced expressions of excitatory/inhibitory synaptic markers, suggesting a transgenerational epigenetic inheritance. These results open the idea that E/I imbalance and ASD-like behavioural changes induced by environmental insults in mice can be epigenetically transmitted, at least, to the third generation. This study could help explain the unprecedented increase in ASD prevalence.
Objectives
White matter hyperintensities (WMHs) are implicated in the etiology of dementia. The underlying pathology of WMHs involves myelin and axonal loss due to chronic ischemia. We investigated ...myelin loss in WMHs and normal-appearing white matter (NAWM) in patients with various degrees of cognitive impairment using quantitative synthetic magnetic resonance imaging (MRI).
Methods
We studied 99 consecutive patients with cognitive complaints who underwent 3 T brain MRI between July 2016 and August 2017. Myelin partial volume maps were generated with synthetic MRI. Region-of-interest–based analysis was performed on these maps to compare the myelin partial volumes of NAWM and periventricular and deep WMHs. The effects of myelin partial volume of NAWMs on clinical cognitive function were evaluated using multivariate linear regression analysis.
Results
WMHs were present in 30.3% of patients. Myelin partial volume in NAWM was lower in patients with WMHs than in those without (37.5 ± 2.7% vs. 39.9 ± 2.4%,
p
< 0.001). In patients with WMHs, myelin partial volume was highest in NAWMs (median interquartile range, 37.2% 35.5–39.0%), followed by deep WMHs (7.2% 3.2–10.5%) and periventricular WMHs (2.1% 1.1–3.9%,
p
< 0.001). After adjusting for sex and education years, myelin partial volume in NAWMs was associated with the Clinical Dementia Rating Scale Sum of Box (
β
= -0.189 95% CI, -0.380 to -0.012,
p
= 0.031).
Conclusion
Myelin loss occurs in both NAWM and WMHs of cognitively impaired patients. Synthetic MRI-based myelin quantification may be a useful imaging marker of cognitive dysfunction in patients with cognitive complaints.
Key Points
•
Quantitative synthetic MRI allows simultaneous acquisition of conventional MRI and myelin quantification without additional scanning time.
•
Normal-appearing and hyperintense white matter demonstrate myelin loss in cognitively impaired patients.
•
This myelin loss partially explains cognitive dysfunction in patients with cognitive complaints.
Chronic cerebral hypoperfusion can lead to ischemic white matter injury resulting in vascular dementia. To characterize white matter injury in vascular dementia, we investigated disintegration of ...diverse white matter components using a rat model of chronic cerebral hypoperfusion.
Chronic cerebral hypoperfusion was modeled in Wistar rats by permanent occlusion of the bilateral common carotid arteries. We performed cognitive behavioral tests, including the water maze task, odor discrimination task, and novel object test; histological investigation of neuroinflammation, oligodendrocytes, myelin basic protein, and nodal or paranodal proteins at the nodes of Ranvier; and serial diffusion tensor imaging. Cilostazol was administered to protect against white matter injury.
Diverse cognitive impairments were induced by chronic cerebral hypoperfusion. Disintegration of white matter was characterized by neuroinflammation, loss of oligodendrocytes, attenuation of myelin density, structural derangement at the nodes of Ranvier, and disintegration of white matter tracts. Cilostazol protected against cognitive impairments and white matter disintegration.
White matter injury induced by chronic cerebral hypoperfusion can be characterized by disintegration of diverse white matter components. Cilostazol might be a therapeutic strategy against white matter disintegration in patients with vascular dementia.
Autism spectrum disorder (ASD) is an immensely challenging developmental disorder characterized primarily by two core behavioral symptoms of social communication deficits and restricted/repetitive ...behaviors. Investigating the etiological process and identifying an appropriate therapeutic target remain as formidable challenges to overcome ASD due to numerous risk factors and complex symptoms associated with the disorder. Among the various mechanisms that contribute to ASD, the maintenance of excitation and inhibition balance emerged as a key factor to regulate proper functioning of neuronal circuitry. Interestingly, our previous study involving the valproic acid animal model of autism (VPA animal model) has demonstrated excitatory-inhibitory imbalance (E/I imbalance) due to enhanced differentiation of glutamatergic neurons and reduced GABAergic neurons. Here, we investigated the potential of agmatine, an endogenous NMDA receptor antagonist, as a novel therapeutic candidate in ameliorating ASD symptoms by modulating E/I imbalance using the VPA animal model. We observed that a single treatment of agmatine rescued the impaired social behaviors as well as hyperactive and repetitive behaviors in the VPA animal model. We also observed that agmatine treatment rescued the overly activated ERK1/2 signaling in the prefrontal cortex and hippocampus of VPA animal models, possibly, by modulating over-excitability due to enhanced excitatory neural circuit. Taken together, our results have provided experimental evidence suggesting a possible therapeutic role of agmatine in ameliorating ASD-like symptoms in the VPA animal model of ASD.
•Single treatment of agmatine rescues social impairment in the VPA-induced animal model of autism.•Effect of agmatine in social improvement in the VPA model is induced from agmatine itself, not its metabolite.•Agmatine rescues repetitive and hyperactive behavior, and seizure susceptibility in the VPA model.•Overly activated ERK1/2 in the brain of the VPA model is relieved by agmatine.
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