Effect size measure for mediation analysis with a multicategorical predictor.

Many currently available effect size measures for mediation have limitations when the predictor is nominal with three or more categories. The mediation effect size measure υ was adopted for this situation. A simulation study was conducted to investigate the performance of its estimators. We manipulated several factors in data generation (number of groups, sample size per group, and effect sizes of paths) and effect size estimation [different R-squared (R 2) shrinkage estimators]. Results showed that the Olkin-Pratt extended adjusted R 2 estimator had the least bias and the smallest MSE in estimating υ across conditions. We also applied different estimators of υ in a real data example. Recommendations and guidelines were provided about the use of this estimator.

The Rapid Naming Test: Development and initial validation in typically aging adults.

ObjectiveProgressive word-finding difficulty is a primary cognitive complaint among healthy older adults and a symptom of pathological aging. Classic measures of visual confrontation naming, however, show ceiling effects among healthy older adults. To address the need for a naming test that is sensitive to subtle, age-related word-finding decline, we developed the Rapid Naming Test (RNT), a computerized, one-minute, speeded visual naming test.MethodFunctionally intact older (n = 145) and younger (n = 69) adults completed the RNT. Subsets of older adults also completed neuropsychological tests, a self-report scale of functional decline, amyloid-ß PET imaging, and repeat RNT administration to determine test-retest reliability.ResultsRNT scores were normally distributed and exhibited good test-retest reliability. Younger adults performed better than older adults. Within older adults, lower scores were associated with older age. Higher scores correlated with measures of language, processing speed, and episodic learning and memory. Scores were not correlated with visuospatial or working memory tests. Worse performance was related to subjective language decline, even after controlling for a classic naming test and speed. The RNT was also negatively associated with amyloid-ß burden.ConclusionsThe RNT appears to be a reliable test that is sensitive to subtle, age-related word-finding decline. Convergent and divergent validity are supported by its specific associations with measures relying on visual naming processes. Ecological validity is supported by its relationship with subjective real-world language difficulties. Lastly, worse performance was related to amyloid-ß deposition, an Alzheimer's disease biomarker. This study represents a key step toward validating a novel, sensitive naming test in typically aging adults.

Health Locus of Control and Neurocognitive Function in Latinx and Non-Latinx White People Living With HIV: A Cross-sectional Study.

ABSTRACT: Research suggests that health locus of control (HLOC) is related to important health and neurocognitive outcomes in people living with HIV. However, the role of ethnicity in these relationships remains poorly understood. This study explored the role of HLOC on neurocognition in a diverse sample of 134 people living with HIV (Latinx: n = 96; non-Latinx White: n = 38) who completed comprehensive neurocognitive evaluations and the Multidimensional HLOC Scale-Form C. Results indicate no ethnocultural differences in HLOC beliefs (ps > .05). External HLOC (i.e., chance and powerful others) related to worse neurocognition in the Latinx group and contributed to significant variance in global neurocognition and learning, memory, and verbal fluency, underscoring the role of external HLOC beliefs on neurocognition, particularly for Latinx individuals. Additional research is needed to better characterize the mechanistic relationship between HLOC beliefs and neurocognitive function and to further explore this relationship among other underrepresented populations also disproportionately affected by HIV.

Variable objective sleep quality is related to worse spatial learning and memory in young adults.

OBJECTIVE: The majority of research on sleep and cognition has focused on mean markers of sleep across multiple nights; however, variable sleep patterns have become increasingly common in the modern era. The purpose of this study was to examine whether objective intraindividual variability in sleep quantity and quality are related to verbal and visuospatial learning and memory functioning in young adults. METHODS: A total of 218 young adult college students were recruited from a university in the Eastern United States, among which 187 participants (70.6% female; mean age = 20.5, SD = 1.5) had complete actigraphy and cognitive performance data. Objective intraindividual means and variabilities of sleep quantity (total sleep time) and sleep quality (percent wake after sleep onset) were measured over a 1- to 2-week timeframe using wrist actigraphy. Verbal and visuospatial learning and memory were assessed using the International Shopping List and Groton Maze Learning tests of the Cogstate computerized test battery. RESULTS: Greater intraindividual variability in actigraphy-derived sleep quality was associated with poorer visuospatial learning and memory performance after controlling for mean sleep quality and visuomotor attention and processing speed (ps < 0.05). Actigraphic measures of sleep quantity were not related to any learning and memory measures. CONCLUSION: In young adults, intraindividual variability in objective sleep quality was significantly related to visuospatial learning and memory, over and above mean sleep quality. Given these associations, future studies should aim to identify modifiable lifestyle and environmental factors contributing to variable sleep quality.

The Brain Health Assessment for Detecting and Diagnosing Neurocognitive Disorders.

BACKGROUND/OBJECTIVES: Brief cognitive screens lack the sensitivity to detect mild cognitive impairment (MCI) or support differential diagnoses. The objective of this study was to validate the 10-minute, tablet-based University of California, San Francisco (UCSF) Brain Health Assessment (BHA) to overcome these limitations. DESIGN: Cross-sectional. SETTING: UCSF Memory and Aging Center. PARTICIPANTS: Older adults (N = 347) (neurologically healthy controls (n = 185), and individuals diagnosed with MCI (n = 99), dementia (n = 42), and as normal with concerns (n = 21)). MEASUREMENTS: The BHA includes subtests of memory, executive function and speed, visuospatial skills, and language and an optional informant survey. Participants completed the Montreal Cognitive Assessment (MoCA) and criterion-standard neuropsychological tests. Standardized structural 3T brain magnetic resonance imaging was performed in 145 participants. RESULTS: At a fixed 85% specificity rate, the BHA had 100% sensitivity to dementia and 84% to MCI; the MoCA had 75% sensitivity to dementia and 25% to MCI. The BHA had 83% sensitivity to MCI likely due to AD and 88% to MCI unlikely due to AD, and the MoCA had 58% sensitivity to MCI likely AD and 24% to MCI unlikely AD. The BHA subtests demonstrated moderate to high correlations with the criterion-standard tests from their respective cognitive domains. Memory test performance correlated with medial temporal lobe volumes; executive and speed with frontal, parietal, and basal ganglia volumes; and visuospatial with right parietal volumes. CONCLUSION: The BHA had excellent combined sensitivity and specificity to detect dementia and MCI, including MCI due to diverse etiologies. The subtests provide efficient, valid measures of neurocognition that are critical in making a differential diagnosis.

Associations Between Tau, ß-Amyloid, and Cognition in Parkinson Disease.

Importance: Multiple disease processes are associated with cognitive impairment in Parkinson disease (PD), including Lewy bodies, cerebrovascular disease, and Alzheimer disease. It remains unknown whether tau pathology relates to cognition in patients with PD without dementia. Objective: To compare tau aggregation in patients with PD who are cognitively normal (PD-CN), patients with PD with mild cognitive impairment (PD-MCI), and healthy control participants, and evaluate the relationships between ß-amyloid (Aß), tau, and cognition in patients with PD who did not have dementia. Design, Setting, and Participants: This cross-sectional study recruited 30 patients with Parkinson disease (15 with PD-CN and 15 with PD-MCI) from a tertiary care medical center and research institutions from July 2015 through October 2016. One patient with PD-MCI did not receive a magnetic resonance imaging scan and thus was excluded from all analyses; 29 patients with PD were included in the present study. Participants underwent tau positron emission tomographic (PET) scanning with fluorine 18-labeled AV-1451, Aß PET scanning with carbon 11-labeled Pittsburgh compound B, magnetic resonance imaging, cognitive testing, and neurologic evaluation. Imaging measures were compared with 49 healthy control participants. Main Outcomes and Measures: Outcomes were tau PET measurements of groups of patients with PD-CN and PD-MCI. We hypothesized that tau aggregation across groups would be related to age and Aß status. Results: Of the 78 participants, 47 (60%) were female, and the mean (SD) age was 71.1 (6.6) years. Six patients with PD (21%) were Aß-positive, of whom 1 was mildly cognitively impaired; 23 were Aß-negative (79%). (Of the 49 healthy controls, 25 were Aß-negative and 24 Aß-positive.) Voxelwise contrasts of whole-brain tau PET uptake between patients with PD-CN and patients with PD-MCI, and additionally between all patients with PD and Aß-negative controls, did not reveal significant differences. Tau PET binding did not differ between patients with PD-MCI and PD-CN in brain regions reflecting Alzheimer disease Braak stages 1/2, 3/4, or 5/6, and did not differ from Aß-negative healthy older adults. Mean (SD) tau PET binding was significantly elevated in Aß-positive patients with PD relative to Aß-negative patients with PD within brain regions reflecting Alzheimer disease Braak stage 3/4 (1.22 [0.07] vs 1.14 [0.07]; P = .03) and Braak stage 5/6 (1.20 [0.07] vs 1.11 [0.08]; P = .02). Conclusions and Relevance: These findings suggest that patterns of cortical Aß and tau do not differ in people with PD-CN, people with PD-MCI, and healthy older adults. Age, Aß, and tau do not differentiate patients with PD-CN and PD-MCI. Tau deposition is related to Aß status and age in both people with PD and healthy older adults. Cognitive deficits in people with PD without dementia do not appear to reflect measureable Alzheimer disease.

The Relationship Between Emotion Regulation, Executive Functioning, and Aggressive Behaviors.

Emotion regulation deficits and executive functioning deficits have independently been shown to increase vulnerability toward engaging in aggressive behaviors. The effects of these risk factors, however, have not been evaluated in relation to one another. This study evaluated the degree to which each was associated with aggressive behaviors in a sample of 168 undergraduate students. Executive functioning (cognitive inhibition and mental flexibility) was assessed with a Stroop-like neuropsychological task. Emotion regulation and aggressive behaviors were assessed via self-report inventories. Results showed main effects for both emotion regulation and executive functioning, as well as a significant interaction, indicating that those who scored lowest in both domains reported engaging in aggressive behaviors the most frequently. When different types of aggression were examined, this interaction was only significant for acts of physical aggression, not for acts of verbal aggression. Therefore, for physical aggression, emotion regulation and executive functioning exerted a moderating effect on one another. The implications are that, at least for acts of physical aggression, relatively strong capabilities in either domain may buffer against tendencies to engage in aggressive behaviors. Thus, both emotion regulation skills and executive functioning abilities may be valuable targets for interventions aiming to reduce aggressive behaviors.