Influences of APOE ε4 and expertise on performance of older pilots

A phase 2, double-blind, placebo-controlled study of NSI-189 phosphate, a neurogenic compound, among outpatients with major depressive disorder

NSI-189 is a novel neurogenic compound independent of monoamine reuptake pathways. This trial evaluated oral NSI-189 as monotherapy in major depressive disorder. To improve signal detection, the sequential-parallel comparison design (SPCD) was chosen. Two hundred and twenty subjects were randomized to NSI-189 40 mg daily, 80 mg daily, or placebo for 12 weeks. The primary outcome measure was the Montogmery Asberg Depression Rating Scale (MADRS). Secondary subject-rated measures included the Symptoms of Depression Questionnaire (SDQ), the Cognitive and Physical Functioning Scale (CPFQ), the patient-rated version of the Quick Inventory of Depressive Symptomatology Scale (QIDS-SR), and subtests from the CogScreen and Cogstate cognitive tests. MADRS score reduction versus placebo did not reach significance for either dose (40 mg pooled mean difference -1.8, p = 0.22, 80 mg pooled mean difference -1.4, p = 0.34, respectively). However, the 40 mg dose showed greater overall reduction in SDQ (pooled mean difference -8.2; Cohen's d for Stages 1 and 2 = -0.11 and -0.64, p = 0.04), and CPFQ scores (pooled mean difference -1.9; Cohen's d for Stages 1 and 2 = -0.28 and -0.47, p = 0.03) versus placebo, as well as QIDS-SR scores in Stage 2 of SPCD (-2.5; Cohen's d Stages 1 and 2 = -0.03 and -0.68, p = 0.04). The 40 mg dose also showed advantages on some objective cognitive measures of the CogScreen (absolute Cohen's d ranged between 0.12 and 1.12 in favor of NSI-189, p values between 0.002 and 0.048 for those with overall significance), but not the Cogstate test. Both doses were well tolerated. These findings replicate those of phase 1b study, and warrant further exploration of the antidepressant and pro-cognitive effects of NSI-189.

Preclinical Alzheimer's disease: Definition, natural history, and diagnostic criteria

During the past decade, a conceptual shift occurred in the field of Alzheimer's disease (AD) considering the disease as a continuum. Thanks to evolving biomarker research and substantial discoveries, it is now possible to identify the disease even at the preclinical stage before the occurrence of the first clinical symptoms. This preclinical stage of AD has become a major research focus as the field postulates that early intervention may offer the best chance of therapeutic success. To date, very little evidence is established on this "silent" stage of the disease. A clarification is needed about the definitions and lexicon, the limits, the natural history, the markers of progression, and the ethical consequence of detecting the disease at this asymptomatic stage. This article is aimed at addressing all the different issues by providing for each of them an updated review of the literature and evidence, with practical recommendations.

The STEP model: Characterizing simultaneous time effects on practice for flight simulator performance among middle-aged and older pilots

Understanding the possible effects of the number of practice sessions (practice) and time between practice sessions (interval) among middle-aged and older adults in real-world tasks has important implications for skill maintenance. Prior training and cognitive ability may impact practice and interval effects on real-world tasks. In this study, we took advantage of existing practice data from 5 simulated flights among 263 middle-aged and older pilots with varying levels of flight expertise (defined by U.S. Federal Aviation Administration proficiency ratings). We developed a new Simultaneous Time Effects on Practice (STEP) model: (a) to model the simultaneous effects of practice and interval on performance of the 5 flights, and (b) to examine the effects of selected covariates (i.e., age, flight expertise, and 3 composite measures of cognitive ability). The STEP model demonstrated consistent positive practice effects, negative interval effects, and predicted covariate effects. Age negatively moderated the beneficial effects of practice. Additionally, cognitive processing speed and intraindividual variability (IIV) in processing speed moderated the benefits of practice and/or the negative influence of interval for particular flight performance measures. Expertise did not interact with practice or interval. Results indicated that practice and interval effects occur in simulated flight tasks. However, processing speed and IIV may influence these effects, even among high-functioning adults. Results have implications for the design and assessment of training interventions targeted at middle-aged and older adults for complex real-world tasks.

Pilot expertise and hippocampal size: associations with longitudinal flight simulator performance

BACKGROUND

Previous research suggests that the size of the hippocampus can vary in response to intensive training (e.g., during the acquisition of expert knowledge). However, the role of the hippocampus in maintenance of skilled performance is not well understood. The Stanford/Veterans Affairs Aviation MRI Study offers a unique opportunity to observe the interaction of brain structure and multiple levels of expertise on longitudinal flight simulator performance.

METHODS

The current study examined the relationship between hippocampal volume and three levels of aviation expertise, defined by pilot proficiency ratings issued by the U.S. Federal Aviation Administration (11). At 3 annual time points, 60 pilots who varied in their level of aviation expertise (ages ranging from 45 to 69 yr) were tested.

RESULTS

At baseline, higher expertise was associated with better flight simulator performance, but not with hippocampal volume. Longitudinally, there was an Expertise x Hippocampal volume interaction, in the direction that a larger hippocampus was associated with better performance at higher levels of expertise.

DISCUSSION

These results are consistent with the notion that expertise in a cognitively demanding domain involves the interplay of acquired knowledge ('mental schemas') and basic hippocampal-dependent processes.

Initial cognitive performance predicts longitudinal aviator performance

OBJECTIVES

The goal of the study was to improve prediction of longitudinal flight simulator performance by studying cognitive factors that may moderate the influence of chronological age.

METHOD

We examined age-related change in aviation performance in aircraft pilots in relation to baseline cognitive ability measures and aviation expertise. Participants were aircraft pilots (N = 276) aged 40-77.9. Flight simulator performance and cognition were tested yearly; there were an average of 4.3 (± 2.7; range 1-13) data points per participant. Each participant was classified into one of the three levels of aviation expertise based on Federal Aviation Administration pilot proficiency ratings: least, moderate, or high expertise.

RESULTS

Addition of measures of cognitive processing speed and executive function to a model of age-related change in aviation performance significantly improved the model. Processing speed and executive function performance interacted such that the slowest rate of decline in flight simulator performance was found in aviators with the highest scores on tests of these abilities. Expertise was beneficial to pilots across the age range studied; however, expertise did not show evidence of reducing the effect of age.

DISCUSSION

These data suggest that longitudinal performance on an important real-world activity can be predicted by initial assessment of relevant cognitive abilities.

The roles of COMT val158met status and aviation expertise in flight simulator performance and cognitive ability

The polymorphic variation in the val158met position of the catechol-O-methyltransferase (COMT) gene is associated with differences in executive performance, processing speed, and attention. The purpose of this study is: (1) replicate previous COMT val158met findings on cognitive performance; (2) determine whether COMT val158met effects extend to a real-world task, aircraft navigation performance in a flight simulator; and (3) determine if aviation expertise moderates any effect of COMT val158met status on flight simulator performance. One hundred seventy two pilots aged 41-69 years, who varied in level of aviation training and experience, completed flight simulator, cognitive, and genetic assessments. Results indicate that although no COMT effect was found for an overall measure of flight performance, a positive effect of the met allele was detected for two aspects of cognitive ability: executive functioning and working memory performance. Pilots with the met/met genotype benefited more from increased levels of expertise than other participants on a traffic avoidance measure, which is a component of flight simulator performance. These preliminary results indicate that COMT val158met polymorphic variation can affect a real-world task.