Ding Geng Chen

Cognitive and Neural Effects of Vision-Based Speed-of-Processing Training in Older Adults with Amnestic Mild Cognitive Impairment: A Pilot Study

To examine the cognitive and neural effects of vision‐based speed‐of‐processing (VSOP) training in older adults with amnestic mild cognitive impairment (aMCI) and contrast those effects with an active control (mental leisure activities (MLA)).

Frequency of Mentally Stimulating Activities Modifies the Relationship Between Cardiovascular Reactivity and Executive Function in Old Age

OBJECTIVES Recent evidence suggests that younger and middle-age adults who show greater cardiovascular reactivity (CVR) to acute mental stress demonstrate better reasoning and memory skills. The purpose of this study was to examine whether older adults would exhibit a similar positive association between CVR and executive function and whether regular engagement in mentally stimulating activities (MSA) would moderate this association. DESIGN Secondary cross-sectional analysis. SETTING Three clinical research centers in the Midwest and on the West Coast and East Coast. PARTICIPANTS A total of 487 older adults participating in an ongoing national survey. MEASUREMENTS Heart rate (HR) and low-frequency (LF) and high-frequency (HF) domains of heart rate variability (HRV) were measured at baseline and in response to standard mental stress tasks (Stroop color word task and mental arithmetic). Executive function was measured separately from the stress tasks by using five neuropsychological tests. MSA was measured by self-reported frequency of six common MSA. RESULTS Higher HR reactivity was associated with better executive function after controlling for demographic and health characteristics and baseline HR, and the interaction between HR reactivity and MSA was significant for executive function. Higher LF-HRV reactivity was also associated with executive function, but subsequent analyses indicated that frequency of MSA was the strongest predictor of executive function in models that included LF-HRV or HF-HRV. CONCLUSIONS Higher HR reactivity to acute psychological stress is related to better executive function in older adults. For those with lower HR reactivity, engaging frequently in MSA produced compensatory benefits for executive function.

Longitudinal effects of metabolic syndrome on Alzheimer and vascular related brain pathology.

Background/Aims: This study examines the longitudinal effect of metabolic syndrome (MetS) on brain-aging indices among cognitively normal (CN) and amnestic mild cognitive impairment (aMCI) groups [single-domain aMCI (saMCI) and multiple-domain aMCI (maMCI)]. Methods: The study population included 739 participants (CN = 226, saMCI = 275, and maMCI = 238) from the Alzheimers Disease Neuroimaging Initiative, a clinic-based, multi-center prospective cohort. Confirmatory factor analysis was employed to determine a MetS latent composite score using baseline data of vascular risk factors. We examined the changes of two Alzheimers disease (AD) biomarkers, namely [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) regions of interest and medial temporal lobe volume over 5 years. A cerebrovascular aging index, cerebral white matter (cWM) volume, was examined as a comparison. Results: The vascular risk was similar in all groups. Applying generalized estimating equation modeling, all brain-aging indices declined significantly over time. Higher MetS scores were associated with a faster decline of cWM in the CN and maMCI groups but with a slower decrement of regional glucose metabolism in FDG-PET in the saMCI and maMCI groups. Conclusion: At the very early stage of cognitive decline, the vascular burden such as MetS may be in parallel with or independent of AD pathology in contributing to cognitive impairment in terms of accelerating the disclosure of AD pathology.

A Note on the Maximum Likelihood Estimation for the Generalized Gamma Distribution Parameters under Progressive Type-II Censoring

Based on the progressively type-Ⅱ censored sample, the maximum likelihood estimates for the parameters of the generalized Gamma distribution are studied. In dealing with the parameter confounding in this distribution, a new re-parametrization is proposed to reformulate the generalized Gamma distribution to sustain the numerical stability in the search algorithm for the maximum likelihood estimation. Intensive simulation is conducted to evaluate the maximum likelihood estimates in terms of the mean squared error and bias via the proposed reparameterization. Finally, a real data set from censored times to breakdown of an insulating fluid is used to demonstrate its applicability.

Cusp Catastrophe Polynomial Model: Power and Sample Size Estimation

Guastello’s polynomial regression method for solving cusp catastrophe model has been widely applied to analyze nonlinear behavior outcomes. However, no statistical power analysis for this modeling approach has been reported probably due to the complex nature of the cusp catastrophe model. Since statistical power analysis is essential for research design, we propose a novel method in this paper to fill in the gap. The method is simulation-based and can be used to calculate statistical power and sample size when Guastello’s polynomial regression method is used to cusp catastrophe modeling analysis. With this novel approach, a power curve is produced first to depict the relationship between statistical power and samples size under different model specifications. This power curve is then used to determine sample size required for specified statistical power. We verify the method first through four scenarios generated through Monte Carlo simulations, and followed by an application of the method with real published data in modeling early sexual initiation among young adolescents. Findings of our study suggest that this simulation-based power analysis method can be used to estimate sample size and statistical power for Guastello’s polynomial regression method in cusp catastrophe modeling.

Kansas City Cardiomyopathy Questionnaire Administered to Hospitalized Patients With Heart Failure.

Background and Purpose: The psychometric properties of the Kansas City Cardiomyopathy Questionnaire (KCCQ) have been examined primarily in community-dwelling patients with heart failure (HF). The objective of this research was to examine the properties of the KCCQ administered to patients hospitalized with HF (N = 233). Methods: Confirmatory factor analysis, Cronbach’s alphas, and correlations were performed to examine the scale’s dimensions, reliability, and validity. Results: Confirmatory factor analysis indicated a 5-factor solution (63.6% of the variance). The Cronbach’s alpha levels were greater than .70, except for the self-efficacy dimension (.60). Convergent validity was not verified between the KCCQ and several illness severity measures. Conclusions: The psychometric properties of the KCCQ may be different based on the population in which the KCCQ is administered, which may have clinical implications.