Polymorphism in the MAGI2 Gene Modifies the Effect of Amyloid ß on Neurodegeneration.

INTRODUCTION: A weak association between amyloid ß (Aß) deposition and neurodegeneration biomarkers, such as brain atrophy, has been repeatedly reported in a subset of patients with Alzheimer disease, suggesting individual differences in response to Aß deposition. METHODS: Here, we performed a genome-wide interaction study to identify single-nucleotide polymorphism (SNP) that modify the effect of Aß (measured by 18F-florbetapir positron emission tomography) on brain atrophy (measured by cortical thickness using magnetic resonance imaging). We used magnetic resonance imaging, positron emission tomography, cerebrospinal fluid, and genetic data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database [discovery cohort, ADNI-GO/2 (n=723) and replication cohort, ADNI-1 (n=129)]. RESULTS: We identified a genome-wide suggestive interaction of rs3807779 SNP (ß=-0.14, SE=0.029, P=9.08×10-7) in the discovery cohort. The greater dosage of rs3807779 SNP increased the detrimental effect of Aß deposition on cortical thickness. In replication analyses, the congruent results were replicated to confirm our findings. Furthermore, rs3807779 SNP augmented the detrimental effect of Aß deposition on cognitive function. Genetic profiling showed that rs3807779 has chromatin interactions with the promoter region of MAGI2 gene, suggesting its association with MAGI2 expression. CONCLUSIONS: These findings demonstrate that subjects carrying the rs3807779 SNP are more susceptible to Aß-related neurodegeneration.

Identifying the Functional Brain Network of Motor Reserve in Early Parkinson's Disease.

BACKGROUND: The severity of motor symptoms in Parkinson's disease (PD) does not always correlate with the degree of nigral dopaminergic neuronal loss. Individuals with greater motor reserve may have milder motor signs than their striatal dopamine loss. In this study, we explored the functional brain network associated with motor reserve in early-stage PD. METHODS: We analyzed 134 patients with de novo PD who underwent dopamine transporter scans and resting-state functional magnetic resonance imaging. We estimated individual motor reserve based on initial motor deficits and striatal dopamine depletion using a residual model. We applied network-based statistic analysis to identify the functional brain network associated with the measure of motor reserve (ie, motor reserve network). We also assessed the effect of motor reserve network connectivity strength on the longitudinal increase in levodopa-equivalent dose during the 2-year follow-up period. RESULTS: Network-based statistic analysis identified the motor reserve network composed of the basal ganglia, inferior frontal cortex, insula, and cerebellar vermis at a primary threshold of P value 0.001. Patients with an increased degree of functional connectivity within the motor reserve network had greater motor reserve. There was a significant interaction between the motor reserve network strength and time in the linear mixed model, indicating that higher motor reserve network strength was associated with slower longitudinal increase in levodopa-equivalent dose. CONCLUSIONS: The present study revealed the functional brain network associated with motor reserve in patients with early-stage PD. Functional connections within the motor reserve network are associated with the individual's capacity to cope with PD-related pathologies. © 2020 International Parkinson and Movement Disorder Society.

Detection of gray matter microstructural changes in Alzheimer's disease continuum using fiber orientation.

BACKGROUND: This study aimed to investigate feasible gray matter microstructural biomarkers with high sensitivity for early Alzheimer's disease (AD) detection. We propose a diffusion tensor imaging (DTI) measure, "radiality", as an early AD biomarker. It is the dot product of the normal vector of the cortical surface and primary diffusion direction, which reflects the fiber orientation within the cortical column. METHODS: We analyzed neuroimages from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, including images from 78 cognitively normal (CN), 50 early mild cognitive impairment (EMCI), 34 late mild cognitive impairment (LMCI), and 39 AD patients. We then evaluated the cortical thickness (CTh), mean diffusivity (MD), which are conventional AD magnetic resonance imaging (MRI) biomarkers, and the amount of accumulated amyloid and tau using positron emission tomography (PET). Radiality was projected on the gray matter surface to compare and validate the changes with different stages alongside other neuroimage biomarkers. RESULTS: The results revealed decreased radiality primarily in the entorhinal, insula, frontal, and temporal cortex with further progression of disease. In particular, radiality could delineate the difference between the CN and EMCI groups, while the other biomarkers could not. We examined the relationship between radiality and other biomarkers to validate its pathological evidence in AD. Overall, radiality showed a high association with conventional biomarkers. Additional ROI analysis revealed the dynamics of AD-related changes as stages onward. CONCLUSION: Radiality in cortical gray matter showed AD-specific changes and relevance with other conventional AD biomarkers with high sensitivity. Moreover, radiality could identify the group differences seen in EMCI, representative of changes in early AD, which supports its superiority in early diagnosis compared to that possible with conventional biomarkers. We provide evidence of structural changes with cognitive impairment and suggest radiality as a sensitive biomarker for identifying early AD.

Comparison of Amyloid ß and Tau Spread Models in Alzheimer's Disease.

Tau and amyloid ß (Aß), 2 key pathogenic proteins in Alzheimer's disease (AD), reportedly spread throughout the brain as the disease progresses. Models of how these pathogenic proteins spread from affected to unaffected areas had been proposed based on the observation that these proteins could transmit to other regions either through neural fibers (transneuronal spread model) or through extracellular space (local spread model). In this study, we modeled the spread of tau and Aß using a graph theoretical approach based on resting-state functional magnetic resonance imaging. We tested whether these models predict the distribution of tau and Aß in the brains of AD spectrum patients. To assess the models' performance, we calculated spatial correlation between the model-predicted map and the actual map from tau and amyloid positron emission tomography. The transneuronal spread model predicted the distribution of tau and Aß deposition with significantly higher accuracy than the local spread model. Compared with tau, the local spread model also predicted a comparable portion of Aß deposition. These findings provide evidence of transneuronal spread of AD pathogenic proteins in a large-scale brain network and furthermore suggest different contributions of spread models for tau and Aß in AD.

Moderate to severe obstructive sleep apnea during REM sleep as a predictor of metabolic syndrome in a Korean population.

PURPOSE: Metabolic syndrome is a cluster of metabolic abnormalities including obesity, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol, and hyperglycemia. Obstructive sleep apnea (OSA) is known to be associated with metabolic syndrome. However, it remains uncertain which sleep parameters of OSA are associated with metabolic syndrome. We aimed to clarify the relationship between sleep variables and the presence of metabolic syndrome in patients with OSA. METHODS: We prospectively recruited patients who visited the institute for the evaluation of sleep-disordered breathing. All patients underwent overnight polysomnography and sleep questionnaires. They were diagnosed with metabolic syndrome according to the 2007 consensus definition by the International Diabetes Federation. We applied multivariate logistic regression models to predict the presence of metabolic syndrome with variables related to sleep parameters. RESULTS: A total of 85 patients (43 men) were enrolled. The mean age (± standard deviation) was 52.0 ± 14.3 years. Metabolic syndrome was diagnosed in 39 (46%) patients. Patients with metabolic syndrome had a significantly higher apnea-hypopnea index (AHI) compared with patients without metabolic syndrome. An AHI greater than 15/h during REM sleep was a significant independent predictor of metabolic syndrome (adjusted OR, 7.08; 95% CI, 1.60-31.41; p = 0.010) after adjusting for age, body mass index, and non-REM AHI ≥ 15/h. In partial correlation analysis, REM AHI was significantly associated with the presence of metabolic syndrome after adjusting for age and BMI (r = 0.229, p = 0.042). CONCLUSION: Korean patients with OSA frequently had comorbid metabolic syndrome. Moderate to severe OSA during REM sleep may be a predictor of metabolic syndrome.

The usefulness of visual rating of posterior atrophy in predicting rapid cognitive decline in Alzheimer disease: A preliminary study.

BACKGROUND: Approximately 10% to 30% of Alzheimer disease (AD) patients progress rapidly in severity and become more dependent on caregivers. Although several studies have investigated whether imaging biomarkers such as medial temporal atrophy (MTA) and posterior atrophy (PA) are useful for predicting the rapid progression of AD, their results have been inconsistent. OBJECTIVE: The study aims to investigate the association of visually rated MTA and PA with rapid disease progression in AD. METHODS: This was a retrospective cohort study of 159 AD patients who were initially diagnosed with mild AD and were followed for 1 year to determine whether they progressed rapidly (a decrease of three points or more on the Mini-Mental State Examination over 1 year). We used 5-point and 4-point visual rating scales to assess MTA and PA, respectively. MTA and PA scores for each patient were dichotomized as normal (without atrophy) or abnormal (atrophy). We performed a logistic regression analysis to determine the odds ratios (ORs) of MTA and PA for rapid disease progression with adjustment for covariates. RESULTS: Within the study population, 47 (29.6%) patients progressed rapidly. Visual assessment of the magnetic resonance imaging (MRI) scans revealed that 112 patients (70.4%) showed MTA, whereas 80 patients (50.3%) showed PA. The ORs with 95% confidence intervals for MTA and PA were 1.825 (0.819-4.070) and 2.844 (1.378-5.835), respectively. The association of visually assessed PA, but not MTA, with rapid progression was significant after adjustment for covariates. CONCLUSION: In patients with mild AD, visual assessment of PA exhibits independent predictive value for rapid disease progression.

Supernumerary phantom limb in a patient with basal ganglia hemorrhage - a case report and review of the literature.

BACKGROUND: Supernumerary phantom limb (SPL) is a rare neurologic phenomenon, in which a patient misperceives an extra limb in addition to the original set of limbs. We report a case of SPL in a patient with a right basal ganglia hemorrhage and review the previous literature about this peculiar phenomenon. CASE PRESENTATION: Two days after the event of a right basal ganglia hemorrhage, a 78-year-old male reported a phantom arm protruding from his left shoulder. He could not see or touch the phantom arm but he felt the presence of an addition arm lateral to his paretic arm. Pain or sensory discomfort were absent in either the paretic arm or the phantom arm. He stated that he could intentionally move the phantom arm independent of his paretic arm. The examination showed that the passive movement of his paretic arm did not elicit any movement of his phantom arm. We diagnosed the SPL as a complication of the hypertensive basal ganglia hemorrhage and treated him with anti-hypertensive medications. His phantom arm persisted for 3 weeks, and it gradually faded away. CONCLUSION: SPL had been reported as a rare complication of various types of cerebral lesions. Right hemispheric lesions were most frequently associated with the SPL. Considering the intentional movement of the phantom arm, we deduced that the SPL might result from the impairment of the sensory feedback system for both internal body image and motor movement.

Association between T1w/T2w ratio in white matter and cognitive function in Alzheimer's disease.

Loss of myelin in the brain may lead to cognitive decline in Alzheimer's disease (AD). The ratio of T1 weighted/T2 weighted (T1w/T2w) on magnetic resonance imaging has been used as a proxy for myelin content in the brain. Using this approach, we investigated the correlation between the white matter (WM) T1w/T2w ratio and both cognitive scores and disease progression in AD. A total of 93 participants who were cognitively unimpaired or diagnosed with mild cognitive impairment or AD dementia were recruited between March 2021 and November 2022. All participants were assessed using neuropsychological tests, and a subset of the participants was assessed every 1 year to monitor disease progression. We observed significant positive associations between the WM T1w/T2w ratio and executive function within the fornix, sagittal stratum, anterior internal capsule, and body of the corpus callosum (False discovery rate [FDR]-corrected P-value < 0.05). There was a marginal interaction between the WM T1w/T2w ratio of the left anterior internal capsule and the longitudinal change in sum of boxes of the Clinical Dementia Rating Scale (FDR-corrected P-value = 0.05). The present study demonstrated that the WM T1w/T2w ratio was associated with executive function and disease progression, suggesting that it may be a novel neuroimaging marker for AD.

Myelin oligodendrocyte glycoprotein antibody-associated disease presenting as unilateral cerebral cortical encephalitis: a case report.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an autoimmune disorder with diverse clinical manifestations including myelitis, meningitis, encephalitis, and optic neuritis. MOGAD rarely presents with unilateral cerebral cortical encephalitis (CCE), rendering the diagnosis difficult in these cases. Furthermore, MOGAD is frequently accompanied by other autoimmune diseases such as thyroid disease or inflammatory bowel disease. Herein, we report a case of unilateral CCE with positive anti-myelin oligodendrocyte glycoprotein (MOG) antibodies. In addition, our patient presented with systemic symptoms as well as neurologic symptoms and was finally diagnosed with ulcerative colitis (UC). A 60-year-old female was admitted to the hospital with an acute onset of headache and fever. Neurological examination revealed left-sided homonymous hemianopsia with intermittent visual hallucinations as flickering red-circular spots in the left visual field. Brain magnetic resonance imaging showed focal hyperintensities and enhancement in the right temporo-parieto-occipital cortex. Electroencephalography indicated a focal seizure in the right occipital cortex. After the administration of an antiepileptic drug, the patient showed clinical and radiological improvements. She tested positive for serum anti-MOG antibodies and was diagnosed with anti-MOG-associated unilateral CCE. However, the gastrointestinal symptoms persisted, thus, a sigmoidoscopy was performed. The patient was diagnosed with comorbid UC. Steroids were administered to treat the UC and the gastrointestinal symptoms improved. To the best of our knowledge, this is the first case of MOGAD presenting as a unilateral CCE in Korea. This case highlights the clinical phenotypes of MOGAD and the need to assess comorbid autoimmune diseases in patients with MOGAD.

Ventral Anterior Cingulate Atrophy as a Predisposing Factor for Transient Global Amnesia.

Background and Purpose: This study aimed to evaluate the brain magnetic resonance imaging (MRI) of patients with acute transient global amnesia (TGA) using volumetric analysis to verify whether the brains of TGA patients have pre-existing structural abnormalities. Methods: We evaluated the brain MRI data from 87 TGA patients and 20 age- and sex-matched control subjects. We included brain MRIs obtained from TGA patients within 72 hours of symptom onset to verify the pre-existence of structural change. For voxel-based morphometric analyses, statistical parametric mapping was employed to analyze the structural differences between patients with TGA and control subjects. Results: TGA patients exhibited significant volume reductions in the bilateral ventral anterior cingulate cortices (corrected p<0.05). Conclusions: TGA patients might have pre-existing structural changes in bilateral ventral anterior cingulate cortices prior to TGA attacks.

A case of hyperacute postvaccinal encephalopathy after BNT162b2 nCoV-19 vaccine.

The global severe acute respiratory syndrome coronavirus 2 pandemic contributed to the development of a large variety of vaccines, of which postvaccinal hyperacute encephalopathy is a very rare complication. Despite its rarity, if diagnosed properly, appropriate treatment can be rapidly applied. A healthy 53-year-old woman was admitted for a seizure on the day she received the second dose of the BNT 162b2 nCoV-19 vaccine. She subsequently developed irritability, which gradually worsened over several days. Cerebrospinal fluid analysis revealed mild pleocytosis and normal protein levels. Brain magnetic resonance imaging (MRI) revealed diffuse sulcal hyperintensity on the entire brain surface on fluid-attenuated inversion recovery images with meningeal enhancement. The patient was diagnosed with hyperacute postvaccinal encephalopathy and received immunosuppressive therapy with corticosteroids and therapeutic plasmapheresis. Fortunately, the patient responded to therapy, achieving almost complete recovery from the neurological symptoms, with only mild memory impairment remaining after 3 weeks. Based on the clinical presentation, electroencephalogram findings, and MRI, our patient developed hyperacute encephalopathy within 24 hours of vaccine administration, which we surmised from the temporal course of symptoms and brain imaging findings. Further studies are required to elucidate the pathogenesis of coronavirus disease 2019 vaccination-related encephalopathy.

Time Perception and Memory in Mild Cognitive Impairment and Alzheimer's Disease: A Preliminary Study.

Background and Purpose: Episodic memory is a system that receives and stores information about temporally dated episodes and their interrelations. Our study aimed to investigate the relevance of episodic memory to time perception, with a specific focus on simultaneity/order judgment. Methods: Experiment 1 employed the simultaneity judgment task to discern differences in time perception between patients with mild cognitive impairment or dementia, and age-matched normals. A mathematical analysis capable of estimating subjects' time processing was utilized to identify the sensory and decisional components of temporal order and simultaneity judgment. Experiment 2 examined how differences in temporal perception relate to performance in temporal order memory, in which time delays play a critical role. Results: The temporal decision windows for both temporal order and simultaneity judgments exhibited marginal differences between patients with episodic memory impairment, and their healthy counterparts (p = 0.15, t(22) = 1.34). These temporal decision windows may be linked to the temporal separation of events in episodic memory (Pearson's ρ = -0.53, p = 0.05). Conclusions: Based on our findings, the frequency of visual events accumulated and encoded in the working memory system in the patients' and normal group appears to be approximately (5.7 and 11.2) Hz, respectively. According to the internal clock model, a lower frequency of event pulses tends to result in underestimation of event duration, which phenomenon might be linked to the observed time distortions in patients with dementia.

Identifying genetic variants for amyloid ß in subcortical vascular cognitive impairment.

Background: The genetic basis of amyloid ß (Aß) deposition in subcortical vascular cognitive impairment (SVCI) is still unknown. Here, we investigated genetic variants involved in Aß deposition in patients with SVCI. Methods: We recruited a total of 110 patients with SVCI and 424 patients with Alzheimer's disease-related cognitive impairment (ADCI), who underwent Aß positron emission tomography and genetic testing. Using candidate AD-associated single nucleotide polymorphisms (SNPs) that were previously identified, we investigated Aß-associated SNPs that were shared or distinct between patients with SVCI and those with ADCI. Replication analyses were performed using the Alzheimer's Disease Neuroimaging Initiative (ADNI) and Religious Orders Study and Rush Memory and Aging Project cohorts (ROS/MAP). Results: We identified a novel SNP, rs4732728, which showed distinct associations with Aß positivity in patients with SVCI (P interaction = 1.49 × 10-5); rs4732728 was associated with increased Aß positivity in SVCI but decreased Aß positivity in ADCI. This pattern was also observed in ADNI and ROS/MAP cohorts. Prediction performance for Aß positivity in patients with SVCI increased (area under the receiver operating characteristic curve = 0.780; 95% confidence interval = 0.757-0.803) when rs4732728 was included. Cis-expression quantitative trait loci analysis demonstrated that rs4732728 was associated with EPHX2 expression in the brain (normalized effect size = -0.182, P = 0.005). Conclusion: The novel genetic variants associated with EPHX2 showed a distinct effect on Aß deposition between SVCI and ADCI. This finding may provide a potential pre-screening marker for Aß positivity and a candidate therapeutic target for SVCI.

Biological Mechanism of Sex Difference in Stroke Manifestation and Outcomes.

BACKGROUND AND OBJECTIVES: Female patients tend to have greater disability and worse long-term outcomes after stroke than male patients. To date, the biological basis of sex difference in ischemic stroke remains unclear. We aimed to (1) assess sex differences in clinical manifestation and outcomes of acute ischemic stroke and (2) investigate whether the sex disparity is due to different infarct locations or different impacts of infarct in the same location. METHODS: This MRI-based multicenter study included 6,464 consecutive patients with acute ischemic stroke (<7 days) from 11 centers in South Korea (May 2011-January 2013). Multivariable statistical and brain mapping methods were used to analyze clinical and imaging data collected prospectively: admission NIH Stroke Scale (NIHSS) score, early neurologic deterioration (END) within 3 weeks, modified Rankin Scale (mRS) score at 3 months, and culprit cerebrovascular lesion (symptomatic large artery steno-occlusion and cerebral infarction) locations. RESULTS: The mean (SD) age was 67.5 (12.6) years, and 2,641 (40.9%) were female patients. Percentage infarct volumes on diffusion-weighted MRI did not differ between female patients and male patients (median 0.14% vs 0.14%, p = 0.35). However, female patients showed higher stroke severity (NIHSS score, median 4 vs 3, p < 0.001) and had more frequent END (adjusted difference 3.5%; p = 0.002) than male patients. Female patients had more frequent striatocapsular lesions (43.6% vs 39.8%, p = 0.001) and less frequent cerebrocortical (48.2% vs. 50.7% in patients older than 52 years, p = 0.06) and cerebellar (9.1% vs. 11.1%, p = 0.009) lesions than male patients, which aligned with angiographic findings: female patients had more prevalent symptomatic steno-occlusion of the middle cerebral artery (MCA) (31.1% vs 25.3%; p < 0.001) compared with male patients, who had more frequent symptomatic steno-occlusion of the extracranial internal carotid artery (14.2% vs 9.3%; p < 0.001) and vertebral artery (6.5% vs 4.7%; p = 0.001). Cortical infarcts in female patients, specifically left-sided parieto-occipital regions, were associated with higher NIHSS scores than expected for similar infarct volumes in male patients. Consequently, female patients had a higher likelihood of unfavorable functional outcome (mRS score >2) than male patients (adjusted absolute difference 4.5%; 95% CI 2.0-7.0; p < 0.001). DISCUSSION: Female patients have more frequent MCA disease and striatocapsular motor pathway involvement with acute ischemic stroke, along with left parieto-occipital cortical infarcts showing greater severity for equivalent infarct volumes than in male patients. This leads to more severe initial neurologic symptoms, higher susceptibility to neurologic worsening, and less 3-month functional independence, when compared with male patients.

Large multi-ethnic genetic analyses of amyloid imaging identify new genes for Alzheimer disease.

Amyloid PET imaging has been crucial for detecting the accumulation of amyloid beta (Aß) deposits in the brain and to study Alzheimer's disease (AD). We performed a genome-wide association study on the largest collection of amyloid imaging data (N = 13,409) to date, across multiple ethnicities from multicenter cohorts to identify variants associated with brain amyloidosis and AD risk. We found a strong APOE signal on chr19q.13.32 (top SNP: APOE ɛ4; rs429358; ß = 0.35, SE = 0.01, P = 6.2 × 10-311, MAF = 0.19), driven by APOE ɛ4, and five additional novel associations (APOE ε2/rs7412; rs73052335/rs5117, rs1081105, rs438811, and rs4420638) independent of APOE ɛ4. APOE ɛ4 and ε2 showed race specific effect with stronger association in Non-Hispanic Whites, with the lowest association in Asians. Besides the APOE, we also identified three other genome-wide loci: ABCA7 (rs12151021/chr19p.13.3; ß = 0.07, SE = 0.01, P = 9.2 × 10-09, MAF = 0.32), CR1 (rs6656401/chr1q.32.2; ß = 0.1, SE = 0.02, P = 2.4 × 10-10, MAF = 0.18) and FERMT2 locus (rs117834516/chr14q.22.1; ß = 0.16, SE = 0.03, P = 1.1 × 10-09, MAF = 0.06) that all colocalized with AD risk. Sex-stratified analyses identified two novel female-specific signals on chr5p.14.1 (rs529007143, ß = 0.79, SE = 0.14, P = 1.4 × 10-08, MAF = 0.006, sex-interaction P = 9.8 × 10-07) and chr11p.15.2 (rs192346166, ß = 0.94, SE = 0.17, P = 3.7 × 10-08, MAF = 0.004, sex-interaction P = 1.3 × 10-03). We also demonstrated that the overall genetic architecture of brain amyloidosis overlaps with that of AD, Frontotemporal Dementia, stroke, and brain structure-related complex human traits. Overall, our results have important implications when estimating the individual risk to a population level, as race and sex will needed to be taken into account. This may affect participant selection for future clinical trials and therapies.

Decreased visual acuity is related to thinner cortex in cognitively normal adults: cross-sectional, single-center cohort study.

BACKGROUND: Decreased visual acuity (VA) is reported to be a risk factor for dementia. However, the association between VA and cortical thickness has not been established. We investigated the association between VA and cortical thickness in cognitively normal adults. METHOD: We conducted a cross-sectional, single-center cohort study with cognitively normal adults (aged ≥ 45) who received medical screening examinations at the Health Promotion Center at Samsung Medical Center. Subjects were categorized as bad (VA ≤ 20/40), fair (20/40 < VA ≤ 20/25), and good (VA > 20/25) VA group by using corrected VA in the Snellen system. Using 3D volumetric brain MRI, cortical thickness was calculated using the Euclidean distance between the linked vertices of the inner and outer surfaces. We analyzed the association between VA and cortical thickness after controlling for age, sex, hypertension, diabetes, dyslipidemia, intracranial volume, and education level. RESULTS: A total of 2756 subjects were analyzed in this study. Compared to the good VA group, the bad VA group showed overall thinner cortex (p = 0.015), especially in the parietal (p = 0.018) and occipital (p = 0.011) lobes. Topographical color maps of vertex-wise analysis also showed that the bad VA group showed a thinner cortex in the parieto-temporo-occipital area. These results were more robust in younger adults (aged 45 to 65) as decreased VA was associated with thinner cortex in more widespread regions in the parieto-temporo-occipital area. CONCLUSION: Our results suggest that a thinner cortex in the visual processing area of the brain is related to decreased visual stimuli.

Ethnic differences in the frequency of ß-amyloid deposition in cognitively normal individuals.

We investigated which factors might explain the differences between the frequencies of brain ß-amyloid (Aß) deposition in Korean and European cognitively normal individuals (CNs). We recruited 434 Korean CNs from the Samsung Medical Center (SMC) and 323 European CNs from the US Alzheimer's Disease Neuroimaging Initiative (ADNI). The Korean CNs showed lower education duration (11.8 ± 4.8 years vs. 16.8 ± 2.5 years, p < 0.001) than the European CNs. The frequency of Aß (+) was higher in the European CNs (32.8%) than in the Korean CNs (20.0%; p < 0.001). In the SMC genome-wide association study (GWAS), 10 variants (including rs7481773 on chromosome 11, located near the brain-derived neurotrophic factor gene) exceeded the genome-wide significance level (p < 5 × 10-8). Especially, rs7481773 carriers showed more rapid decline in memory function than non-carriers (p = 0.048). However, this association was not observed in the ADNI GWAS. Our findings suggested that the different frequencies of Aß (+) between CN Koreans and Europeans might be related to decreased cognitive reserve or genetic factors.

Cortical neuroanatomical changes related to specific language impairments in primary progressive aphasia.

Objective: Language function test-specific neural substrates in Korean patients with primary progressive aphasia (PPA) might differ from those in other causes of dementia and English-speaking PPA patients. We investigated the correlation between language performance tests and cortical thickness to determine neural substrates in Korean patients with PPA. Materials and methods: Ninety-six patients with PPA were recruited from the memory clinic. To acquire neural substrates, we performed linear regression using the scores of each language test as a predictor, cortical thickness as an outcome and age, sex, years of education, and intracranial volume as confounders. Results: Poor performance in each language function test was associated with lower cortical thickness in specific cortical regions: (1) object naming and the bilateral anterior to mid-portion of the lateral temporal and basal temporal regions; (2) semantic generative naming and the bilateral anterior to mid-portion of the lateral temporal and basal temporal regions; (3) phonemic generative naming and the left prefrontal and inferior parietal regions; and (4) comprehension and the left posterior portion of the superior and middle temporal regions. In particular, the neural substrates of the semantic generative naming test in PPA patients, left anterior to mid-portion of the lateral and basal temporal regions, quite differed from those in patients with other causes of dementia. Conclusion: Our findings provide a better understanding of the different pathomechanisms for language impairments among PPA patients from those with other causes of dementia.

Transferability of Alzheimer Disease Polygenic Risk Score Across Populations and Its Association With Alzheimer Disease-Related Phenotypes.

Importance: Polygenic risk scores (PRSs), which aggregate the genetic effects of single-nucleotide variants identified in genome-wide association studies (GWASs), can help distinguish individuals at a high genetic risk for Alzheimer disease (AD). However, genetic studies have predominantly focused on populations of European ancestry. Objective: To evaluate the transferability of a PRS for AD in the Korean population using summary statistics from a prior GWAS of European populations. Design, Setting, and Participants: This cohort study developed a PRS based on the summary statistics of a large-scale GWAS of a European population (the International Genomics of Alzheimer Project; 21 982 AD cases and 41 944 controls). This PRS was tested for an association with AD dementia and its related phenotypes in 1634 Korean individuals, who were recruited from 2013 to 2019. The association of a PRS based on a GWAS of a Japanese population (the National Center for Geriatrics and Gerontology; 3962 AD cases and 4074 controls) and a transancestry meta-analysis of European and Japanese GWASs was also evaluated. Data were analyzed from December 2020 to June 2021. Main Outcomes and Measures: Risk of AD dementia, amnestic mild cognitive impairment (aMCI), earlier symptom onset, and amyloid ß deposition (Aß). Results: A total of 1634 Korean patients (969 women [59.3%]), including 716 individuals (43.6%) with AD dementia, 222 (13.6%) with aMCI, and 699 (42.8%) cognitively unimpaired controls, were analyzed in this study. The mean (SD) age of the participants was 71.6 (9.0) years. Higher PRS was associated with a higher risk of AD dementia independent of APOE ɛ4 status in the Korean population (OR, 1.95; 95% CI, 1.40-2.72; P < .001). Furthermore, PRS was associated with aMCI, earlier symptom onset, and Aß deposition independent of APOE ɛ4 status. The PRS based on a transancestry meta-analysis of data sets comprising 2 distinct ancestries showed a slightly improved accuracy. Conclusions and Relevance: In this cohort study, a PRS derived from a European GWAS identified individuals at a high risk for AD dementia in the Korean population. These findings emphasize the transancestry transferability and clinical value of PRSs and suggest the importance of enriching diversity in genetic studies of AD.

Effects of Electrical Automatic Massage on Cognition and Sleep Quality in Alzheimer's Disease Spectrum Patients: A Randomized Controlled Trial.

PURPOSE: Muscle relaxation following electrical automatic massage (EAM) has been found to reduce fatigue, depression, stress, anxiety, and pain in individuals with various conditions. However, the effects of EAM have not been extensively explored in patients with Alzheimer's disease (AD). MATERIALS AND METHODS: Here, we conducted a randomized controlled study to evaluate the effects of EAM on the cognitive and non-cognitive functions of patients with AD spectrum disorders. RESULTS: We found that EAM attenuated changes in attention-associated cognitive scores and subjective sleep quality relative to those in controls. CONCLUSION: While further studies in a clinical setting are needed to support our findings, these encouraging results suggest that EAM may be an alternative therapy for the management of associated symptoms in AD (ClinicalTrials.gov ID: NCT03507192, 24/04/2018).