Distinct performance profiles on the Brixton test in frontotemporal dementia

The Brixton Spatial Anticipation Test is a well-established test of executive function that evaluates the capacity to abstract, follow, and switch rules. There has been remarkably little systematic analysis of Brixton test performance in the prototypical neurodegenerative disorder of the frontal lobes: behavioural variant frontotemporal dementia (bvFTD) or evaluation of the test’s ability to distinguish frontal from temporal lobe degenerative disease. We carried out a quantitative and qualitative analysis of Brixton performance in 76 patients with bvFTD and 34 with semantic dementia (SD) associated with temporal lobe degeneration. The groups were matched for demographic variables and illness duration. The bvFTD group performed significantly more poorly (U = 348, p < .0001, r = .58), 53% of patients scoring in the poor–impaired range compared with 6% of SD patients. Whereas bvFTD patients showed problems in rule acquisition and switching, SD patients did not, despite their impaired conceptual knowledge. Error analysis revealed more frequent perseverative errors in bvFTD, particularly responses unconnected to the stimulus, as well as random responses. Stimulus-bound errors were rare. Within the bvFTD group, there was variation in performance profile, which could not be explained by demographic, neurological, or genetic factors. The findings demonstrate sensitivity and specificity of the Brixton test in identifying frontal lobe degenerative disease and highlight the clinical value of qualitative analysis of test performance. From a theoretical perspective, the findings provide evidence that semantic knowledge and the capacity to acquire rules are dissociable. Moreover, they exemplify the separable functional contributions to executive performance.     

Selecting the “Best” Factor Structure and Moving Measurement Validation Forward: An Illustration

Despite the broad literature base on factor analysis best practices, research seeking to evaluate a measure's psychometric properties frequently fails to consider or follow these recommendations. This leads to incorrect factor structures, numerous and often overly complex competing factor models and, perhaps most harmful, biased model results. Our goal is to demonstrate a practical and actionable process for factor analysis through (a) an overview of six statistical and psychometric issues and approaches to be aware of, investigate, and report when engaging in factor structure validation, along with a flowchart for recommended procedures to understand latent factor structures; (b) demonstrating these issues to provide a summary of the updated Posttraumatic Stress Disorder Checklist (PCL–5) factor models and a rationale for validation; and (c) conducting a comprehensive statistical and psychometric validation of the PCL–5 factor structure to demonstrate all the issues we described earlier. Considering previous research, the PCL–5 was evaluated using a sample of 1,403 U.S. Air Force remotely piloted aircraft operators with high levels of battlefield exposure. Previously proposed PCL–5 factor structures were not supported by the data, but instead a bifactor model is arguably more statistically appropriate.     

Lifestyle differences between smokers,ex-smokers and non-smokers,and implications for their health

Abstract

Much evidence has been published in order to demonstrate that smoking cessation leads to a decrease in morbidity and mortality. Using data from the Health and Lifestyle Survey respondents were divided into three groups: smokers, ex-smokers and non-smokers and lifestyle characteristics such as diet and exercise were compared. Smokers were more likely to eat chips (French fries), fried food, butter and less likely to eat fresh fruit in winter, green vegetables and margarine high in polyunsaturated fats. Non-smokers were more likely than smokers and ex-smokers to take part in keepfit, jogging and swimming. Non-smokers in smoking households were more likely than non-smokers in non-smoking households to eat fried food, chips and butter and less likely to eat fruit in winter or margarine high in polyunsaturated fats. Results suggest that part of the assumed health benefits of smoking cessation are due to ex-smokers having a healthier diet than that of smokers.     

The link between mental rotation ability and basic numerical representations

Mental rotation and number representation have both been studied widely, but although mental rotation has been linked to higher-level mathematical skills, to date it has not been shown whether mental rotation ability is linked to the most basic mental representation and processing of numbers. To investigate the possible connection between mental rotation abilities and numerical representation, 43 participants completed four tasks: 1) a standard pen-and-paper mental rotation task; 2) a multi-digit number magnitude comparison task assessing the compatibility effect, which indicates separate processing of decade and unit digits; 3) a number-line mapping task, which measures precision of number magnitude representation; and 4) a random number generation task, which yields measures both of executive control and of spatial number representations. Results show that mental rotation ability correlated significantly with both size of the compatibility effect and with number mapping accuracy, but not with any measures from the random number generation task. Together, these results suggest that higher mental rotation abilities are linked to more developed number representation, and also provide further evidence for the connection between spatial and numerical abilities.