Accounting for retest effects in cognitive testing with the Bayesian double exponential model via intensive measurement burst designs

The effects of the Multicultural Healthy Diet on cognitive decline & Alzheimer's disease risk: A randomized controlled trial in middle-aged adults

BACKGROUND

Anti-inflammatory dietary patterns are associated with slower cognitive decline in older adults; however, little is known about effects of an anti-inflammatory dietary pattern in middle-age.

OBJECTIVES

To adapt an anti-inflammatory diet to a multicultural setting and assess its impact on cognitive decline and Alzheimer's Disease risk and related dementias in healthy middle-aged adults.

METHODS

We performed a phase II pilot randomized clinical trial in adults (40-65 years old; n=290) in Bronx, New York. Participants were assigned to follow either the Multicultural Healthy Diet (MHD) an anti-inflammatory diet, or usual diet (Comparison). Diet was evaluated using National Cancer Institute's Automated Self-Administered 24-hr food records. The primary cognitive outcome was assessed at 9 months following randomization using a global composite score derived from three ambulatory cognitive assessments of visuospatial memory (Grid Memory), processing speed (Symbol Search) and short-term associative memory binding (Color Shapes). Secondary outcomes included performance on individual tests and association of dietary components with cognitive performance.

RESULTS

At 9 month follow-up the MHD arm had a lower Dietary Inflammatory Index (DII) score based on self-reported diet, with an adjusted MHD minus Comparison difference of -0.64 (95% CI: -1.02, -0.27) and -0.94 (95% CI: -1.34, -0.54) for the DII and energy-adjusted DII scores respectively, indicating intervention participants had adhered to an anti-inflammatory dietary pattern. Group session and telephone contact completion averaged 93% and 72% respectively for the MHD arm. No statistically significant difference between arms was found in the primary outcome- cognitive global score change- from baseline: -0.06 (95% CI: -0.15, 0.04), p=0.259.

CONCLUSIONS

The MHD was feasible and acceptable in this multicultural US cohort. While the influence of MHD at 9 months was non-significant based on the composite cognitive score, additional research using other measures such as day-to-day variability in cognitive function and peak performance is warranted.

CLINICAL TRIAL REGISTRY NUMBER

NCT03240406, https://clinicaltrials.gov/study/NCT03240406?term=Diet%20%26%20Cognition&page=3&rank=30. The protocol can be accessed at this website.

Cognitive Health Benefits of Everyday Physical Activity in a Diverse Sample of Middle-Aged Adults

BACKGROUND

Physical activity has been associated with a wide range of health benefits including long-term benefits for cognitive and brain health. Whether episodes of everyday physical activity are associated with immediate cognitive benefits remains unknown.

PURPOSE

The purpose of the current study was to examine whether episodes of physical activity, occurring over the course of participants' daily lives, are associated with short-term improvements in cognitive health.

METHODS

Participants completed a 9-day ecological momentary assessment protocol involving 5 daily assessments of self-reported physical activity and ambulatory cognitive assessments of processing speed and visuospatial working memory. Data were analyzed in a multilevel modeling framework to explore changes in performance on each task associated with physical activity during the period leading up to the assessment as well as individual differences in average frequency of physical activity.

RESULTS

Results of MLMs indicated that engaging in physical activity during the period (~3.5 hr) leading up to an assessment was associated with improvements in processing speed equivalent to 4 years of cognitive aging. Such improvements were observed for both light and moderate-to-vigorous physical activity levels. No association was observed for visuospatial working memory accuracy; however, response time during the working memory task reliably mirrored the association observed for processing speed. The short-term benefits were observed, particularly, for individuals with an overall higher frequency of reported physical activity.

CONCLUSIONS

Our findings suggest that engaging in everyday physical activity of any intensity level may have short-term, acute benefits for cognitive health and point to new potential targets for intervention.

CLINICAL TRIAL INFORMATION

NCT03240406.

Cognotoxemia: endotoxemia and gender predict changes in working memory performance in healthy adults

Introduction

Examining the contribution of peripheral systems to cognitive function under healthy circumstances may improve our understanding of the systems that confer risk or resilience in diseased states. Endotoxemia-a pro-inflammatory response to the translocation of bacteria that reside in the gut on other sources (e.g., respiratory tract; infection) into the blood-was hypothesized to relate to worsened cognitive functioning. Gender was explored as a moderator.

Methods

A sample of 162 healthy adults (25-65 years old) provided plasma, from which a measure of endotoxemia was determined [i.e., the ratio of lipopolysaccharide binding protein (LBP) to soluble cluster of differentiation 14 receptors (sCD14)]. Participants performed an array of laboratory and ambulatory cognitive tasks at three timepoints, each separated by 9 months. Two sets of multilevel models were used: Prospective models, linking endotoxemia at baseline with changes in cognition across time, and coupling models, which examine correlations of endotoxemia with cognition across time.

Results

A prospective model indicated lower levels of endotoxemia at baseline predicted improvements in working memory across the three timepoints; higher levels were associated with no change in cognitive performance. Gender was not found to modulate this finding. Interestingly, a coupling analysis of endotoxemia and gender across time showed that in men, those with higher endotoxemia performed better at the working memory task overall; in women, working memory performance was similar regardless of endotoxemia level.

Conclusion

This work provides initial evidence that endotoxemia may be associated with a dampening of improvement in working memory, improvement consistent with practice effects, which should be expected in a sample of healthy, relatively young adults. The findings also provide preliminary evidence that, at least for men, higher degrees of endotoxemia are not inherently negative, and may link with short term positive outcomes for working memory.

Remote Digital Technologies for the Early Detection and Monitoring of Cognitive Decline in Patients With Type 2 Diabetes: Insights From Studies of Neurodegenerative Diseases

Type 2 diabetes (T2D) is a risk factor for cognitive decline. In neurodegenerative disease research, remote digital cognitive assessments and unobtrusive sensors are gaining traction for their potential to improve early detection and monitoring of cognitive impairment. Given the high prevalence of cognitive impairments in T2D, these digital tools are highly relevant. Further research incorporating remote digital biomarkers of cognition, behavior, and motor functioning may enable comprehensive characterizations of patients with T2D and may ultimately improve clinical care and equitable access to research participation. The aim of this commentary article is to review the feasibility, validity, and limitations of using remote digital cognitive tests and unobtrusive detection methods to identify and monitor cognitive decline in neurodegenerative conditions and apply these insights to patients with T2D.

Perceived but not objective measures of neighborhood safety and food environments are associated with longitudinal changes in processing speed among urban older adults

BACKGROUND

Although a growing body of literature documents the importance of neighborhood effects on late-life cognition, little is known about the relative strength of objective and subjective neighborhood measures on late-life cognitive changes. This study examined effects of objective and subjective neighborhood measures in three neighborhood domains (neighborhood safety, physical disorder, food environments) on longitudinal changes in processing speed, an early marker of cognitive aging and impairment.

METHODS

The analysis sample included 306 community-dwelling older adults enrolled in the Einstein Aging Study (mean age = 77, age range = 70 to 91; female = 67.7%; non-Hispanic White: 45.1%, non-Hispanic Black: 40.9%). Objective and subjective measures of neighborhood included three neighborhood domains (i.e., neighborhood safety, physical disorder, food environments). Processing speed was assessed using a brief Symbol Match task (unit: second), administered on a smartphone device six times a day for 16 days and repeated annually for up to five years. Years from baseline was used as the within-person time index.

RESULTS

Results from mixed effects models showed that subjective neighborhood safety (β= -0.028) and subjective availability of healthy foods (β= -0.028) were significantly associated with less cognitive slowing over time. When objective and subjective neighborhood measures were simultaneously examined, subjective availability of healthy foods remained significant (β= -0.028) after controlling for objective availability of healthy foods. Associations of objective neighborhood crime and physical disorder with processing speed seemed to be confounded by individual-level race and socioeconomic status; after controlling for these confounders, none of objective neighborhood measures showed significant associations with processing speed.

CONCLUSION

Subjective neighborhood safety and subjective availability of healthy foods, rather than objective measures, were associated with less cognitive slowing over time over a five-year period. Perception of one's neighborhood may be a more proximal predictor of cognitive health outcomes as it may reflect one's experiences in the environment. It would be important to improve our understanding of both objective and subjective neighborhood factors to improve cognitive health among older adults.

Utilizing Technology to Enhance the Ecological Validity of Cognitive and Functional Assessments in Schizophrenia: An Overview of the State-of-the-Art

Cognitive impairment is a core feature of schizophrenia and a key determinant of functional outcome. Although conventional paper-and-pencil based cognitive assessments used in schizophrenia remained relatively static during most of the 20th century, this century has witnessed the emergence of innovative digital technologies that aim to enhance the ecological validity of performance-based assessments. This narrative review provides an overview of new technologies that show promise for enhancing the ecological validity of cognitive and functional assessments. We focus on 2 approaches that are particularly relevant for schizophrenia research: (1) digital functional capacity tasks, which use simulations to measure performance of important daily life activities (e.g., virtual shopping tasks), delivered both in-person and remotely, and (2) remote device-based assessments, which include self-administered cognitive tasks (e.g., processing speed test) or functionally-focused surveys regarding momentary activities and experiences (e.g., location, social context), as well as passive sensor-based metrics (e.g., actigraphy measures of activity), during daily life. For each approach, we describe the potential for enhancing ecological validity, provide examples of select measures that have been used in schizophrenia research, summarize available data on their feasibility and validity, and consider remaining challenges. Rapidly growing evidence indicates that digital technologies have the potential to enhance the ecological validity of cognitive and functional outcome assessments, and thereby advance research into the causes of, and treatments for, functional disability in schizophrenia.