Measuring Human Auditory Evoked Fields with a Flexible Multi-Channel OPM-Based MEG System.

BACKGROUND: Magnetoencephalography (MEG) is a non-invasive imaging technique for directly measuring the external magnetic field generated from synchronously activated pyramidal neurons in the brain. The optically pumped magnetometer (OPM) is known for its less expensive, non-cryogenic, movable and user-friendly custom-design provides the potential for a change in functional neuroimaging based on MEG. METHODS: An array of OPMs covering the opposite sides of a subject's head is placed inside a magnetically shielded room (MSR) and responses evoked from the auditory cortices are measured. RESULTS: High signal-to-noise ratio auditory evoked response fields (AEFs) were detected by a wearable OPM-MEG system in a MSR, for which a flexible helmet was specially designed to minimize the sensor-to-head distance, along with a set of bi-planar coils developed for background field and gradient nulling. Neuronal current sources activated in AEF experiments were localized and the auditory cortices showed the highest activities. Performance of the hybrid optically pumped magnetometer-magnetoencephalography/electroencephalography (OPM-MEG/EEG) system was also assessed. CONCLUSIONS: The multi-channel OPM-MEG system performs well in a custom built MSR equipped with bi-planar coils and detects human AEFs with a flexible helmet. Moreover, the similarities and differences of auditory evoked potentials (AEPs) and AEFs are discussed, while the operation of OPM-MEG sensors in conjunction with EEG electrodes provides an encouraging combination for the exploration of hybrid OPM-MEG/EEG systems.

A Multi-Modal Classification Method for Early Diagnosis of Mild Cognitive Impairment and Alzheimer's Disease Using Three Paradigms With Various Task Difficulties.

Alzheimer's Disease (AD) accounts for the majority of dementia, and Mild Cognitive Impairment (MCI) is the early stage of AD. Early and accurate diagnosis of dementia plays a vital role in more targeted treatments and effectively halting disease progression. However, the clinical diagnosis of dementia requires various examinations, which are expensive and require a high level of expertise from the doctor. In this paper, we proposed a classification method based on multi-modal data including Electroencephalogram (EEG), eye tracking and behavioral data for early diagnosis of AD and MCI. Paradigms with various task difficulties were used to identify different severity of dementia: eye movement task and resting-state EEG tasks were used to detect AD, while eye movement task and delayed match-to-sample task were used to detect MCI. Besides, the effects of different features were compared and suitable EEG channels were selected for the detection. Furthermore, we proposed a data augmentation method to enlarge the dataset, designed an extra ERPNet feature extract layer to extract multi-modal features and used domain-adversarial neural network to improve the performance of MCI diagnosis. We achieved an average accuracy of 88.81% for MCI diagnosis and 100% for AD diagnosis. The results of this paper suggest that our classification method can provide a feasible and affordable way to diagnose dementia.

Brain Activation During Working Memory Task in Amnestic Mild Cognitive Impairment Patients and Its Association with Memory and Attention.

BACKGROUND: Amnestic mild cognitive impairment (aMCI) is regarded as a transitional state of Alzheimer's disease, with working memory (WM) impairment. OBJECTIVE: To investigate the brain activity in aMCI patients during WM tasks with the functional near-infrared spectroscopy (fNIRS) technique, as well as explore the association between brain activity and cognitive function in multiple domains. METHODS: This study is a case-control study of 54 aMCI patients and 33 cognitively healthy elderly (NC). All participants underwent neuropsychological assessments. fNIRS was applied to examine the brain activation during the WM task. Multivariable linear regression analysis was applied to evaluate associations between brain activation and cognitive function in multiple domains. RESULTS: Compared to NC subjects, aMCI patients had lower activation in the bilateral prefrontal, parietal, and occipital cortex during the WM task. Additionally, activation in the left prefrontal, bilateral parietal, and occipital cortex during the encoding and maintenance phase was positively associated with memory function. During memory retrieval, higher activity in the left prefrontal, parietal, and occipital cortex were correlated with higher memory scores. Besides, a positive association also formed between attention function and the activation in the left prefrontal, parietal, and occipital cortex during the WM task. CONCLUSION: These findings demonstrated that reduced activation in the prefrontal, parietal and occipital cortex during WM might reflect the risk of cognitive impairment, especially memory and attention function in aMCI patients. Given the brain activation visualization, fNIRS may be a convenient and alternative tool for screening the risk of Alzheimer's disease.

Diagnostic accuracy of multi-component spatial-temporal gait parameters in older adults with amnestic mild cognitive impairment.

Objective: This study aimed to develop a diagnostic model of multi-kinematic parameters for patients with amnestic mild cognitive impairment (aMCI). Method: In this cross-sectional study, 94 older adults were included (33 cognitively normal, CN; and 61 aMCI). We conducted neuropsychological battery tests, such as global cognition and cognitive domains, and collected gait parameters by an inertial-sensor gait analysis system. Multivariable regression models were used to identify the potential diagnostic variables for aMCI. Receiver operating characteristic (ROC) curves were applied to assess the diagnostic accuracy of kinematic parameters in discriminating aMCI from healthy subjects. Results: Multivariable regression showed that multi-kinematic parameters were the potential diagnostic variables for aMCI. The multi-kinematic parameter model, developed using Timed Up and Go (TUG) time, stride length, toe-off/heel stride angles, one-leg standing (OLS) time, and braking force, showed areas under ROC (AUC), 0.96 [95% confidence interval (CI), 0.905-0.857]; sensitivity, 0.90; and specificity, 0.91. In contrast, a single kinematic parameter's sensitivity was 0.26-0.95 and specificity was 0.21-0.90. Notably, the separating capacity of multi-kinematic parameters was highly similar to Montreal Cognitive Assessment (MoCA; AUC: 0.96 vs. 0.95). Compared to cognitive domain tests, the separating ability was comparable to Auditory Verbal Learning Test (AVLT) and Boston Naming Test (BNT; AUC: 0.96 vs. 0.97; AUC: 0.96 vs. 0.94). Conclusion: We developed one diagnostic model of multi-kinematic parameters for patients with aMCI in Foshan.

High Fall Risk Associated With Memory Deficit and Brain Lobes Atrophy Among Elderly With Amnestic Mild Cognitive Impairment and Mild Alzheimer's Disease.

Objectives: This study aimed to primarily examine the association between memory deficit and increased fall risk, second, explore the underlying neuroanatomical linkage of this association in the elderly with aMCI and mild AD. Methods: In this cross-sectional study, a total of 103 older adults were included (55 cognitively normal, CN; 48 cognitive impairment, CI, elderly with aMCI, and mild AD). Memory was assessed by the Auditory Verbal Learning Test (AVLT). Fall risk was evaluated by the Timed Up and Go (TUG) Test, heel strike angles, and stride speed, which were collected by an inertial-sensor-based wearable instrument (the JiBuEn™ gait analysis system). Brain volumes were full-automatic segmented and quantified using AccuBrain® v1.2 from three-dimensional T1-weighted (3D T1W) MR images. Multivariable regression analysis was used to examine the extent of the association between memory deficit and fall risk, the association of brain volumes with memory, and fall risk. Age, sex, education, BMI, and HAMD scores were adjusted. Sensitivity analysis was conducted. Results: Compared to CN, participants with aMCI and mild AD had poorer cognitive performance (p < 0.001), longer TUG time (p = 0.018), and smaller hippocampus and medial temporal volumes (p = 0.037 and 0.029). In the CI group, compared to good short delayed memory (SDM) performance (AVLT > 5), the elderly with bad SDM performance (AVLT ≤ 3) had longer TUG time, smaller heel strike angles, and slower stride speed. Multivariable regression analysis showed that elderly with poor memory had higher fall risk than relative good memory performance among cognitive impairment elderly. The TUG time increased by 2.1 s, 95% CI, 0.54∼3.67; left heel strike angle reduced by 3.22°, 95% CI, -6.05 to -0.39; and stride speed reduced by 0.09 m/s, 95% CI, -0.19 to -0.00 for the poor memory elderly among the CI group, but not found the association in CN group. In addition, serious medial temporal atrophy (MTA), small volumes of the frontal lobe and occipital lobe were associated with long TUG time and small heel strike angles; small volumes of the temporal lobe, frontal lobe, and parietal lobe were associated with slow stride speed. Conclusion: Our findings suggested that memory deficit was associated with increased fall risk in the elderly with aMCI and mild AD. The association might be mediated by the atrophy of medial temporal, frontal, and parietal lobes. Additionally, increased fall risk, tested by TUG time, heel stride angles, and stride speed, might be objective and convenient kinematics markers for dynamic monitoring of both memory function and fall risk.

Sleep duration and efficiency are associated with plasma amyloid-ß in non-demented older people.

STUDY OBJECTIVES: This study aims to investigate the extent to which sleep duration and efficiency are associated with plasma amyloid-ß (Aß) levels in non-demented older people. METHODS: This study is a cross-sectional analysis of 305 non-demented older people. Sleep duration and efficiency were assessed used the Pittsburgh Sleep Quality Index. Levels of plasma Aß were determined by sandwich enzyme-linked immunosorbent assay technique. Associations between sleep variables and plasma Aß levels were evaluated with multivariable linear regression analysis. RESULTS: Compared to those with sleep duration > 7 h, participants with sleep duration < 6 h had a higher plasma Aß42 level (ß = 0.495, 95% CI 0.077~0.913, p = 0.021) and Aß42/Aß40 ratio (ß = 0.101, 95% CI 0.058~0.144, p < 0.001). Compared to those with sleep efficiency ≥ 85%, participants with lower sleep efficiency (65~74%, <65%) had a higher level of plasma Aß42 (<65%: ß = 0.627, 95% CI 0.147~1.108, p = 0.011) and Aß42/Aß40 ratio (65~74%: ß = 0.052, 95% CI 0.007~0.097, p = 0.026; <65%: ß = 0.117, 95% CI 0.067~0.168, p < 0.001). CONCLUSIONS: These findings indicated that short sleep duration and low sleep efficiency were associated with a high level of Aß42. A better comprehending of the link between sleep and plasma Aß levels may lead to effective sleep-based intervention to reduce the risk of Alzheimer's disease.

Subjective Sleep Quality in Amnestic Mild Cognitive Impairment Elderly and Its Possible Relationship With Plasma Amyloid-ß.

STUDY OBJECTIVES: To investigate the extent to which sleep quality associated with plasma Aß levels in amnestic mild cognitive impairment (aMCI) elderly. METHODS: A total of 172 cognitively normal (NC) elderly and 133 aMCI elderly were included in this study. For the evaluation of sleep quality, the Pittsburgh Sleep Quality Index (PSQI) was used. Levels of plasma Aß were determined by the sandwich enzyme-linked immunosorbent assay technique. Multivariable linear regression analysis was applied to evaluate associations between sleep quality and plasma Aß levels after adjusting potential confounders. RESULTS: Compared to NC subjects, participants with aMCI had a higher global PSQI score (8.72 ± 3.87 vs. 7.10 ± 3.07, p < 0.001). The global PSQI score was positively associated with plasma Aß42 level in the aMCI group (ß = 0.063, 95% CI 0.001-0.125, and p = 0.049) but not in the NC group (p > 0.05). Additionally, a higher global PSQI score was associated with a higher plasma Aß42/Aß40 ratio in both NC (ß = 0.010, 95% CI 0.003-0.016, and p = 0.003) and aMCI groups (ß = 0.012, 95% CI 0.005-0.018, and p < 0.001). The association between global PSQI score and plasma Aß42/Aß40 ratio was stronger in individuals with aMCI relative to the NC subjects (ß = 0.076 vs. 0.030, p for interaction = 0.023). CONCLUSION: Poor sleep quality was associated with plasma Aß42 and Aß42/Aß40 ratio, with a stronger effect among individuals with aMCI. A better understanding of the role of sleep in plasma Aß levels in aMCI patients could lead to effective sleep-based intervention against the risk of Alzheimer's disease.

Wearable Sensor-Based Daily Life Walking Assessment of Gait for Distinguishing Individuals With Amnestic Mild Cognitive Impairment.

Objectives: To characterize gait disorders in patients with amnestic mild cognitive impairment (aMCIs) and determine the association between the performance of the gait function and cognition. Methodology: In this study, we enrolled 38 patients with aMCI and 30 cognitively normal individuals normal controls (NC). Neuropsychological assessments included tests of memory, executive function, language, and attention. Using an inertial-sensor-based wearable instrument, we collected the gait data dynamically for at least 1 h/day for 2 weeks. The gait parameters included walking velocity, stride length, stride time, cadence, and stride time variability. Results: The aMCI patients had reduced walking velocity and stride length and increased stride time variability compared with the NCs. The total number of steps, stride time, and cadence did not differ between the two groups. For all the subjects, walking velocity and stride length was positively associated with memory and executive function. Stride time variability was negatively correlated with the cognitive domains including memory, executive function and attention. Conclusion: This study suggested that cognitive impairment-related gait disorders occur (reduced gait speed, gait length, and gait stability) in daily life walking among the aMCI patients. A sensor-based wearable device for gait measurement may be an alternative and convenient tool for screening cognitive impairment.

Corrigendum: Age-Dependent Relationship Between Plasma Aß40 and Aß42 and Total Tau Levels in Cognitively Normal Subjects.

[This corrects the article DOI: 10.3389/fnagi.2019.00222.].

Age-Dependent Relationship Between Plasma Aß40 and Aß42 and Total Tau Levels in Cognitively Normal Subjects.

Both amyloid plaques and neurofibrillary tangles are pathological hallmarks in the brains of patients with Alzheimer's disease (AD). However, the constituents of these hallmarks, amyloid beta (Aß) 40, Aß42, and total Tau (t-Tau), have been detected in the blood of cognitively normal subjects by using an immunomagnetic reduction (IMR) assay. Whether these levels are age-dependent is not known, and their interrelation remains undefined. We determined the levels of these biomarkers in cognitively normal subjects of different age groups. A total of 391 cognitively normal subjects aged 23-91 were enrolled from hospitals in Asia, Europe, and North America. Healthy cognition was evaluated by NIA-AA guidelines to exclude subjects with mild cognitive impairment (MCI) and AD and by cognitive assessment using the Mini Mental State Examination and Clinical Dementia Rating (CDR). We examined the effect of age on plasma levels of Aß40, Aß42, and t-Tau and the relationship between these biomarkers during aging. Additionally, we explored age-related reference intervals for each biomarker. Plasma t-Tau and Aß42 levels had modest but significant correlations with chronological age (r = 0.127, p = 0.0120 for t-Tau; r = -0.126, p = 0.0128 for Aß42), ranging from ages 23 to 91. Significant positive correlations were detected between Aß42 and t-Tau in the groups aged 50 years and older, with Rho values ranging from 0.249 to 0.474. Significant negative correlations were detected between Aß40 and t-Tau from age 40 to 91 (r ranged from -0.293 to -0.582) and between Aß40 and Aß42 in the age groups of 30-39 (r = -0.562, p = 0.0235), 50-59 (r = -0.261, p = 0.0142), 60-69 (r = -0.303, p = 0.0004), and 80-91 (r = 0.459, p = 0.0083). We also provided age-related reference intervals for each biomarker. In this multicenter study, age had weak but significant effects on the levels of Aß42 and t-Tau in plasma. However, the age group defined by decade revealed the emergence of a relationship between Aß40, Aß42, and t-Tau in the 6th and 7th decades. Validation of our findings in a large-scale and longitudinal study is warranted.

Is hyperhomocysteinemia associated with the structural changes of the substantia nigra in Parkinson's disease? A two-year follow-up study.

OBJECTIVE: It was recently found that structural changes in the substantia nigra (SN) and motor symptoms become more prominent in Parkinson's disease (PD) patients with striatal silent lacunar infarction (SSLI) than in those without SSLI. Hyperhomocysteinemia (HHCY) was an independent risk factor for SSLI in PD patients. In this follow-up study, we investigated the relationship between HHCY and structural changes of the SN in PD patients. METHODS: A total of 72 untreated early PD patients without SSLI, divided into control and HHCY groups, were enrolled in this study. All participants underwent conventional MRI and diffusion kurtosis imaging (DKI) twice; at baseline and at the 2-year visit. The differences of the following variables between the two groups were analyzed: mean kurtosis (MK) values of the SN, the severity of disease, daily dosage of levodopa, and the variation of these indexes from baseline to 2-year visit. Logistic regression analysis was used to identify the relationship between HHCY and structural changes of the SN in PD patients. RESULTS: 1.All variables mentioned above showed significant differences between the two groups. 2. The variation in MK values of the SN were positively correlated with the variation in the severity of disease. 3. HHCY was an independent risk factor for the variation in MK values of the SN in PD patients. CONCLUSION: HHCY is associated with the structural changes of the SN in PD patients. As PD progresses, motor symptoms become aggravated with increased structural changes to the SN, especially in patients with HHCY.

The etiological effect of a new low-frequency ESR1 variant on Mild Cognitive Impairment and Alzheimer's Disease: a population-based study.

Latent genetic variations of cholesterol metabolism-related genes in late-onset Alzheimer's disease, especially, as well as in mild cognitive impairment pathogenesis are still to be studied extensively. Thus, we performed the targeted-sequencing of 12 nuclear receptor genes plus APOE which were involved in cholesterol content modulation to screen susceptible genetic variants and focused on a new risk variant ESR1 rs9340803 at 6q25.1 for both late-onset Alzheimer's disease (OR=3.30[1.84~4.22], p<0.001) and mild cognitive impairment (OR=3.08[1.75~3.89], p<0.001). This low-frequency variant was validated in three independent cohorts totaling 854 late-onset Alzheimer's disease cases, 1059 mild cognitive impairment cases and 1254 controls from nine provinces of China mainland. Preliminary functional study on it revealed decreased ESR1 expression in vitro. Besides, we detected higher serum Aß1-40 concentration in participants carrying this variant (p=0.038) and lower plasma total cholesterol level in this variant carriers with late-onset Alzheimer's disease (p=0.009). In summary, we identified a susceptible variant which might contribute to developing mild cognitive impairment at earlier stage and Alzheimer's Disease later. Our study would provide new insight into the disease causation of late-onset Alzheimer's disease and could be exploited therapeutically.

The cost of Alzheimer's disease in China and re-estimation of costs worldwide.

INTRODUCTION: The socioeconomic costs of Alzheimer's disease (AD) in China and its impact on global economic burden remain uncertain. METHODS: We collected data from 3098 patients with AD in 81 representative centers across China and estimated AD costs for individual patient and total patients in China in 2015. Based on this data, we re-estimated the worldwide costs of AD. RESULTS: The annual socioeconomic cost per patient was US $19,144.36, and total costs were US $167.74 billion in 2015. The annual total costs are predicted to reach US $507.49 billion in 2030 and US $1.89 trillion in 2050. Based on our results, the global estimates of costs for dementia were US $957.56 billion in 2015, and will be US $2.54 trillion in 2030, and US $9.12 trillion in 2050, much more than the predictions by the World Alzheimer Report 2015. DISCUSSION: China bears a heavy burden of AD costs, which greatly change the estimates of AD cost worldwide.

Higher Adiposity Is Associated With Slower Cognitive Decline in Hypertensive Patients: Secondary Analysis of the China Stroke Primary Prevention Trial.

BACKGROUND: Obesity is a risk factor for many diseases. However, the potential association between adiposity and cognitive decline in hypertensive patients is inconclusive. We performed a secondary data analysis of the CSPPT (China Stroke Primary Prevention Trial) to examine whether adiposity is correlated with longitudinal cognitive performance in hypertensive adults. METHODS AND RESULTS: The analysis included 16 791 patients in the CSPPT who received at least 2 cognitive assessments by the Mini-Mental State Examination (MMSE) during the follow-up (median, 4.5 years; interquartile range, 4.2-4.8 years). Outcomes included changes in MMSE scores and cognitive impairment (defined as MMSE score less than education-specific cutoff point). A marked reduction in MMSE scores at the final (compared with at the 1-year) follow-up was apparent in both men (n=4838; mean [SD] score, 0.41 [3.62]) and women (n=7190; mean [SD] score, 1.07 [4.61]; both P<0.001). Analysis using a mixed-effects model revealed an association between higher body mass index with less MMSE decline, even after controlling for demographics and comorbidities (men, ß=0.0134 [SE, 0.0036]; women, ß=0.0133 [SE, 0.0034]; both P<0.001). A total of 1037 men (15.3%) and 3317 women (33.1%) developed cognitive impairment. In multivariable Cox regression analyses, being obese in men (11.3% versus 18.0%; hazard ratio, 0.75; 95% confidence interval, 0.60-0.94) and women (30.1% versus 36.5%; hazard ratio, 0.82; 95% confidence interval, 0.74-0.91) was a protective factor against cognitive impairment compared with normal body mass index. CONCLUSIONS: Higher adiposity is independently associated with slower cognitive decline in Chinese hypertensive adults. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885 CSPPT.

The effects of striatal silent lacunar infarction on the substantia nigra and movement disorders in Parkinson's disease: A follow-up study.

OBJECTIVE: Striatal silent lacunar infarction (SSLI) is associated with structural changes to the substantia nigra (SN), detectable by diffusion kurtosis imaging (DKI). In this follow-up study, we investigated the effects of SSLI on the SN and movement disorders in patients with Parkinson's disease (PD). METHODS: A total of 60 untreated patients with early-stage PD, divided into control and SSLI groups, were enrolled in this study. All participants underwent conventional MRI and DKI twice; at baseline and after a 1-year period. We analyzed the differences of the following variables between the two groups: mean kurtosis (MK) values of the SN, the severity of disease, daily dosage of levodopa, and the variation of these indexes from baseline to 1-year visit. Logistic regression analysis was used to identify the major risk factors for SSLI in PD patients. RESULTS: 1. All variables showed significant differences between the two groups. 2. The variation in MK values of the SN had a positive correlation with the variation in the severity of disease. 3. Hypertension and hyperhomocysteinemia were independent factors for SSLI in patients with PD. CONCLUSION: As PD progresses, movement disorders become more prominent, with increased structural changes to the SN, especially in patients with SSLI. Furthermore, PD patients with hypertension and hyperhomocysteinemia are more likely to have SSLI.

Elevated Plasma Homocysteine Level Increased the Risk of Early Renal Impairment in Acute Ischemic Stroke Patients.

Renal insufficiency is associated with the prognosis of acute ischemic stroke (AIS) and homocysteine (Hcy) levels. This study investigated the association between plasma Hcy levels and renal insufficiency in patients with AIS. A total of 987 patients with AIS who had been treated at the First People's Hospital of Foshan between 2011 and 2014 were retrospectively studied. Based on their cystatin C (Cys C) levels, the patients were divided into the normal renal function group (Cys C ≤ 1.25 mg/L) or the renal impairment group (Cys C > 1.25 mg/L). Multivariate regression analysis was applied to reveal the association between hyperhomocysteinemia (HHcy) and renal impairment. The renal impairment group showed more advanced age of onset, higher percentage of prior stroke and hypertension, higher baseline National Institute of Health Stroke Scale score, lower high-density lipoprotein cholesterol levels, and higher Hcy levels compared with the normal renal function group. A multivariate analysis revealed a relationship between early renal impairment and Hcy levels: an increase of Hcy by 1 µmol/L was associated with an increase of 12-18% of the risk of renal impairment among patients with AIS and HHcy. Patients with AIS and HHcy had a 2.42-3.51 fold increase of the risk of renal impairment compared with patients with normal Hcy level (P < 0.001). In conclusion, patients with stroke and HHcy could be more prone to renal impairment.

Striatal silent lacunar infarction is associated with changes to the substantia nigra in patients with early-stage Parkinson's disease: A diffusion kurtosis imaging study.

A recent study has shown that striatal silent infarction may occur secondary to the degeneration of dopaminergic neurons in the substantia nigra (SN) of mice. However, it is uncertain whether this phenomenon occurs in patients with early-stage Parkinson's disease (PD) and can be detected by diffusion kurtosis imaging (DKI). A total of 72 untreated patients with early-stage PD underwent conventional MRI and DKI. Participants were divided into control and striatal silent lacunar infarction (SSLI) groups. The differences in mean kurtosis (MK) values of the SN, Hoehn-Yahr (H-Y) staging, and Unified Parkinson's Disease Rating Scale (UPDRS) III score between groups, were analyzed. Linear regression analysis was used to correlate age, SSLI count, silent lacunar infarction count in other brain areas and age-related white matter change score with MK values of the SN. Spearman correlation coefficient analysis was used to correlate MK values of the SN and SSLI count with H-Y staging and UPDRS III score. There was no significant difference in the severity of disease between two groups; however, MK values of the SN with SSLI present were significantly higher than in SN without SSLI. In addition, SSLI count had linear correlation with MK values of the SN, which had positive correlation with H-Y-staging and UPDRS III score. SSLI is associated with structural changes to the SN in patients with early-stage PD, detectable by DKI, and may aggravate their motor impairments.

Distinct Patterns of Cognitive Aging Modified by Education Level and Gender among Adults with Limited or No Formal Education: A Normative Study of the Mini-Mental State Examination.

BACKGROUND: Dementia is increasingly prevalent due to rapid aging of the population, but under-recognized among people with low education levels. This is partly due to a lack of appropriate and precise normative data, which underestimates cognitive aging in the use of screening tools for dementia. OBJECTIVE: We aimed to improve the precision of screening for cognitive impairment, by characterizing the patterns of cognitive aging and derived normative data of the Mini-Mental State Examination (MMSE) for illiterate and low-educated populations. METHODS: This community-based study included data from 2,280 individuals aged 40 years or older from two rural areas. Multiple linear modeling examined the effect of aging on cognition reflected by the MMSE, stratified by education level and gender. Threshold effect of age on cognition was performed using a smoothing function. RESULTS: The majority of participants (60.4%) were illiterate or had attended only primary school (24.6%). The effect of aging on cognition varied by gender and education. Primary-school educated females and males remained cognitively stable up to 62 and 71 years of age, respectively, with MMSE score declining 0.4 and 0.8 points/year in females and males thereafter. Illiterates females scored 2.3 points lower than illiterate males, and scores for both declined 0.2 points/year. According to these results, normative data stratified by age, education and gender was generated. CONCLUSION: This study suggests gender and educational differences exist in cognitive aging among adults with limited or no formal education. To improve screening precision for cognitive impairment with the use of MMSE in low-educated population, age, gender, and education level should be considered.

Diffusion Kurtosis Imaging of Substantia Nigra Is a Sensitive Method for Early Diagnosis and Disease Evaluation in Parkinson's Disease.

Background. To diagnose Parkinson disease (PD) in an early stage and accurately evaluate severity, it is important to develop a sensitive method for detecting structural changes in the substantia nigra (SN). Method. Seventy-two untreated patients with early PD and 72 healthy controls underwent diffusion tensor and diffusion kurtosis imaging. Regions of interest were drawn in the rostral, middle, and caudal SN by two blinded and independent raters. Mean kurtosis (MK) and fractional anisotropy in the SN were compared between the groups. Receiver operating characteristic (ROC) and Spearman correlation analyses were used to compare the diagnostic accuracy and correlate imaging findings with Hoehn-Yahr (H-Y) staging and part III of the Unified Parkinson's Disease Rating Scale (UPDRS-III). Result. MK in the SN was increased significantly in PD patients compared with healthy controls. The area under the ROC curve was 0.976 for MK in the SN (sensitivity, 0.944; specificity, 0.917). MK in the SN had a positive correlation with H-Y staging and UPDRS-III scores. Conclusion. Diffusion kurtosis imaging is a sensitive method for PD diagnosis and severity evaluation. MK in the SN is a potential biomarker for imaging studies of early PD that can be widely used in clinic.