Sleep-wake behavior, perceived fatigability, and cognitive reserve in older adults.

INTRODUCTION: The effects of sleep-wake behavior on perceived fatigability and cognitive abilities when performing daily activities have not been investigated across levels of cognitive reserve (CR). METHODS: CR Index Questionnaire (CRIq) data were collected and subjected to moderated mediation analysis. RESULTS: In amnestic mild cognitive impairment (aMCI; n = 41), CR moderated sleep-related impairments (SRIs), and fatigability at low CR (CRIq < 105.8, p = 0.004) and mean CR (CRIq = 126.9, p = 0.03) but not high CR (CRIq > 145.9, p = 0.65) levels. SRI affected cognitive abilities mediated by fatigability at low CR (p < 0.001) and mean CR (p = 0.003) levels. In healthy controls (n = 13), SRI in fatigability did not alter cognitive abilities across CR levels; controls had higher leisure scores than patients with aMCI (p = 0.003, effect size = 0.93). DISCUSSION: SRI can amplify impaired cognitive abilities through exacerbation of fatigability in patients with aMCI with below-mean CR. Therefore, improving sleep-wake regulation and leisure activities may protect against fatigability and cognitive decline. HIGHLIGHTS: Clinical fatigue and fatigability cannot be alleviated by rest. Clinical fatigability disrupts daily activities during preclinical Alzheimer's. High cognitive reserve mitigates sleep-wake disturbance effects. High cognitive reserve attenuates clinical fatigability effects on daily functioning. Untreated obstructive sleep apnea potentiates Alzheimer's pathology in the brain.

Validity of the Web-Based, Self-Directed, NeuroCognitive Performance Test in Mild Cognitive Impairment.

BACKGROUND: Digital cognitive tests offer several potential advantages over established paper-pencil tests but have not yet been fully evaluated for the clinical evaluation of mild cognitive impairment. OBJECTIVE: The NeuroCognitive Performance Test (NCPT) is a web-based, self-directed, modular battery intended for repeated assessments of multiple cognitive domains. Our objective was to examine its relationship with the Alzheimer's Disease Assessment Scale-Cognition Subscale (ADAS-Cog) and Mini-Mental State Examination (MMSE) as well as with established paper-pencil tests of cognition and daily functioning in mild cognitive impairment (MCI). METHODS: We used Spearman correlations, regressions and principal components analysis followed by a factor analysis (varimax rotated) to examine our objectives. RESULTS: In MCI subjects, the NCPT composite is significantly correlated with both a composite measure of established tests (r = 0.78, p < 0.0001) as well as with the ADAS-Cog (r = -0.55, p < 0.0001). Both NCPT and paper-pencil test batteries had a similar factor structure that included a large "g" component with a high eigenvalue. The correlation for the analogous tests (e.g., Trails A and B, learning memory tests) were significant (p < 0.0001). Further, both the NCPT and established tests significantly (p < 0.0001) predicted the University of California San Diego Performance-Based Skills Assessment and Functional Activities Questionnaire, measures of daily functioning. CONCLUSION: The NCPT, a web-based, self-directed, computerized test, shows high concurrent validity with established tests and hence offers promise for use as a research or clinical tool in MCI. Despite limitations such as a relatively small sample, absence of control group and cross-sectional nature, these findings are consistent with the growing literature on the promise of self-directed, web-based cognitive assessments for MCI.

Computerized Games versus Crosswords Training in Mild Cognitive Impairment.

BACKGROUND: Mild cognitive impairment (MCI) increases the risk of dementia. The efficacy of cognitive training in patients with MCI is unclear. METHODS: In a two-site, single-blinded, 78-week trial, participants with MCI - stratified by age, severity (early/late MCI), and site - were randomly assigned to 12 weeks of intensive, home-based, computerized training with Web-based cognitive games or Web-based crossword puzzles, followed by six booster sessions. In mixed-model analyses, the primary outcome was change from baseline in the 11-item Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) score, a 70 point scale in which higher scores indicate greater cognitive impairment at 78 weeks, adjusted for baseline. Secondary outcomes included change from baseline in neuropsychological composite score, University of California San Diego Performance-Based Skills Assessment (functional outcome) score, and Functional Activities Questionnaire (functional outcome) score at 78 weeks, adjusted for baseline. Changes in hippocampal volume and cortical thickness on magnetic resonance imaging were assessed. RESULTS: Among 107 participants (n=51 [games]; n=56 [crosswords]), ADAS-Cog score worsened slightly for games and improved for crosswords at week 78 (least squares [LS] means difference, -1.44; 95% confidence interval [CI], -2.83 to -0.06; P=0.04). From baseline to week 78, mean ADAS-Cog score worsened for games (9.53 to 9.93) and improved for crosswords (9.59 to 8.61). The late MCI subgroup showed similar results (LS means difference, -2.45; SE, 0.89; 95% CI, -4.21 to -0.70). Among secondary outcomes, the Functional Activities Questionnaire score worsened more with games than with crosswords at week 78 (LS means difference, -1.08; 95% CI, -1.97 to -0.18). Other secondary outcomes showed no differences. Decreases in hippocampal volume and cortical thickness were greater for games than for crosswords (LS means difference, 34.07; SE, 17.12; 95% CI, 0.51 to 67.63 [hippocampal volume]; LS means difference, 0.02; SE, 0.01; 95% CI, 0.00 to 0.04 [cortical thickness]). CONCLUSIONS: Home-based computerized training with crosswords demonstrated superior efficacy to games for the primary outcome of baseline-adjusted change in ADAS-Cog score over 78 weeks. (Supported by the National Institutes of Health, National Institute on Aging; ClinicalTrials.gov number, NCT03205709.).

Critical skating intensity on a slide board: physiological and neuromuscular responses and correlation with performance on ice.

The aim of this study was to assess the physiological and neuromuscular responses at critical skating intensity on a slide board and to investigate the correlations between critical cadence (CC) and skating performances on ice. Thirteen well-trained speed skaters (age,19.8 ± 4.2 years; weight, 69.6 ± 9.06 kg) performed a maximal skating incremental test (IT) on a slide board. CC was determined from 3 to 4 trials to exhaustion lasting from 3.1 ± 0.7 to 13.9 ± 3.1 min, using linear and hyperbolic mathematical fittings. A time to exhaustion test at CC (TTE-CC) was performed. CC values (55.3 ± 5.0 ppm) were significantly higher than cadence at the respiratory compensation point (RCP) (53.5 ± 4.0 ppm). Mean duration of TTE-CC was 22.9 ± 4.8 min. Peak values of oxygen uptake, heart rate (HR), ventilation, respiratory exchange ratio (RER), and ratings of perceived exertion (RPE) during TTE-CC were significantly lower (p < 0.05) than the peak values reached during the IT. Oxygen uptake, HR, ventilation, RER, and RPE significantly increased from 25% to 100% of TTE-CC. Muscle activity (integrated electromyography) significantly increased after 75% of TTE-CC for vastus lateralis and gluteus maximus muscles. Oxygen uptake at CC was better associated to skating performance on 500, 1000, 1500, and 5000 m than peak oxygen uptake at IT and oxygen uptake at RCP. Physiological responses indicate that critical skating intensity on slide board occurred within the heavy exercise domain where oxygen uptake increases but does not reach its maximum. Critical cadence could be used as a better indicator of performance and training prescription for long track speed skating distances.

Incidental nest predation in freshwater turtles: inter- and intraspecific differences in vulnerability are explained by relative crypsis.

There has long been interest in the influence of predators on prey populations, although most predator-prey studies have focused on prey species that are targets of directed predator searching. Conversely, few have addressed depredation that occurs after incidental encounters with predators. We tested two predictions stemming from the hypothesis that nest predation on two sympatric freshwater turtle species whose nests are differentially prone to opportunistic detection-painted turtles (Chrysemys picta) and snapping turtles (Chelydra serpentina)-is incidental: (1) predation rates should be density independent, and (2) individual predators should not alter their foraging behavior after encountering nests. After monitoring nest survival and predator behavior following nest depredation over 2 years, we confirmed that predation by raccoons (Procyon lotor), the primary nest predators in our study area, matched both predictions. Furthermore, cryptic C. picta nests were victimized with lower frequency than more detectable C. serpentina nests, and nests of both species were more vulnerable in human-modified areas where opportunistic nest discovery is facilitated. Despite apparently being incidental, predation on nests of both species was intensive (57% for painted turtles, 84% for snapping turtles), and most depredations occurred within 1 day of nest establishment. By implication, predation need not be directed to affect prey demography, and factors influencing prey crypsis are drivers of the impact of incidental predation on prey. Our results also imply that efforts to conserve imperiled turtle populations in human-modified landscapes should include restoration of undisturbed conditions that are less likely to expose nests to incidental predators.

Semantic processing in alcoholics with and without antisocial symptomatology.

OBJECTIVE: Chronic alcoholics with a comorbid diagnosis of antisocial personality (ASP) symptomatology often exhibit early onset, severe course, and poor treatment outcomes. In addition, antisocial characteristics have been associated with a variety of cognitive deficits, including abnormalities of semantic processing, a deficit also found in alcoholics. Using the N400 task, this study investigated whether comorbid ASP symptomatology in alcoholics and community controls contributes to deficits in cognitive efficiency. METHOD: The N400 component of the event-related potential was elicited in detoxified alcoholics (n = 71; 56 male) and community controls (n = 36; 22 female) by sentences with congruent, related/incongruent or unrelated/incongruent terminal words. Difference waveforms were derived, and both amplitude and latency measures were obtained. Antisocial personality symptomatology was assessed using the ASP section of the Diagnostic Interview Schedule IV. RESULTS: Data were analyzed via linear regression using alcoholism, ASP positive (ASP+) status and their interaction term as predictors of N400 amplitude and latency. Significant latency findings were noted in the related/incongruent sentence condition. Increased N400 latency was predicted by ASP+ status at electrode site Pz (p = .01). The interaction of alcoholism and ASP+ status predicted increased N400 latency at electrode site P4 (p = .009), with ASP+ alcoholics demonstrating the greatest latency. CONCLUSIONS: The presence of N400 latency differences in response to related/incongruent semantic information in the current study differs from previous findings in studies of chronic alcoholism that do not account for ASP. These data suggest that antisocial personality disorder and alcoholism may affect cognitive function via different underlying mechanisms.

A comparison of substance abuse among female offender subtypes.

The relationship between substance abuse and female criminal offending has been understudied. To aid in clarification of this relation, substance use histories of female offender subtypes were compared. Participants were 152 female prison inmates subgrouped on the basis of offense category: violent (n = 79), property (n = 39), and drug (n = 34). As hypothesized, substance use histories differed across offender subgroups. Violent offenders were most clearly distinguished from other offender subgroups. The data provide evidence linking alcohol, combined cocaine and alcohol, and marijuana misuse with serious violent offending among women and show that violent offenders, compared with other offender subgroups, perceive less association between alcohol consumption and alcohol-related negative consequences.