Traumatic Brain Injury as a Risk Factor for Alzheimer's Disease: A Review

Accumulating epidemiological evidence implicates traumatic brain injury as a pathogenic agent in the development of Alzheimer's disease (AD). Considering the increase in the prevalence of both traumatic brain injury and AD in recent times, the possibility that brain trauma may provoke the early development of AD has important implications for health service planning, preventative efforts, and medico-legal compensation settlements. This paper evaluates the plausibility of the proposed link between traumatic brain injury and AD, largely by way of exploring a theoretical perspective advanced by Satz (1993) and considering recent contributions from the epidemiological, neuropathological, and biochemical literature that are pertinent to this issue. The literature reviewed provides sufficient support and empirical vindication to give credence to the proposed association between these two neuropsychological entities at the statistical, theoretical, and biological level.     

Attention capacity and task difficulty in visual search

When a visual search task is very difficult (as when a small feature difference defines the target), even detection of a unique element may be substantially slowed by increases in display set size. This has been attributed to the influence of attentional capacity limits. We examined the influence of attentional capacity limits on three kinds of search task: difficult feature search (with a subtle featural difference), difficult conjunction search, and spatial-configuration search. In all 3 tasks, each trial contained sixteen items, divided into two eight-item sets. The two sets were presented either successively or simultaneously. Comparison of accuracy in successive versus simultaneous presentations revealed that attentional capacity limitations are present only in the case of spatial-configuration search. While the other two types of task were inefficient (as reflected in steep search slopes), no capacity limitations were evident. We conclude that the difficulty of a visual search task affects search efficiency but does not necessarily introduce attentional capacity limits.     

Developing a Community Science Research Agenda for Building Community Capacity for Effective Preventive Interventions

Research has shown that prevention programming can improve community health when implemented well. There are examples of successful prevention in local communities, however many continue to face significant challenges, demonstrating a gap between science and practice. Common strategies within the United States to address this gap are available (e.g., trainings), but lack outcomes. Building community capacity to implement high quality prevention can help communities achieve positive health outcomes, thereby narrowing the gap. While there is ample research on the efficacy of evidence-based programs, there is little on how to improve community capacity to improve prevention quality. In order to narrow the gap, a new model of research—one based in Community Science—is suggested that improves the latest theoretical understanding of community capacity and evaluates technologies designed to enhance it. In this article, we describe this model and suggest a research agenda that can lead to improved outcomes at the local level.     

Faulty Judgment,Expert Opinion,and Decision-Making Capacity

An assessment of decision-making capacity is the accepted procedure for determining when a person is not competent. An inferential gap exists between the criteria for capacity specific abilities and the legal requirements to understand relevant information and appreciate the consequences of a decision. This gap extends to causal influences on a person'scapacity to decide. Using a published case of depression, we illustrate that assessors' uses of diagnostic information is frequently not up to the task of bridging this inferential gap in a justifiable way. We then describe cases of faulty judgement which challenge the understanding of diagnostic causal influences. These cases help to clarify the nature of the expertise required for capacity assessments. In practice, the requirements of decision-making capacity are often abandoned to other considerations due to a lack of requisite expertise. The legal policy supporting decision-making capacity as a means to protective intervention is justified only if the requisite expertise is developed. We propose the requisite expertise to be developed in the long term as a distinct multidisciplinary endeavour.     

Satiation, capacity, and within-session responding

Responding may change substantially over the course of a session (McSweeney, Hinson, & Cannon, 1996). The role of satiation in this effect was investigated in three experiments. Experiment 1 showed that the capacity of pigeons to consume milo over a 1-hr period was relatively stable across three different methods of measurement. In Experiment 2, pigeons were divided into two groups that differed in their capacity based on one of those measures. Key pecking was then reinforced under a variable-interval 30-s schedule with hopper durations of 2 or 5 s. According to the satiation hypothesis, subjects with small capacities should satiate faster and therefore show greater decreases in food-reinforced responding than would subjects with larger capacities. The results confirmed this prediction and showed that the magnitudes of within-session decreases were better predicted by the amount an animal consumed relative to its capacity than by absolute amount alone. In Experiment 3, each pigeon was prefed 0, 5, 15, or 25 g of milo prior to each session. Consistent with the satiation hypothesis, increases in prefeeding produced lower overall response rates in the smaller capacity subjects than in the larger capacity subjects at each level of prefeeding. These experiments demonstrate the importance of a new variable in the control of behavior, and provide a recommended technique for its measurement.     

Perceived Discrimination and Health-Related Quality of Life: Testing the Reserve Capacity Model in Hispanic Americans

ABSTRACT

This study tested aspects of the Reserve Capacity Model (Gallo & Matthews, 2003 Gallo, L. C. and Matthews, K. A. 2003. Understanding the association between socioeconomic status and physical health: Do negative emotions play a role?. Psychological Bulletin, 129: 10–51. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Gallo, Penedo Espinosa de los Monteros, & Arguelles, 2009 Gallo, L. C., Penedo, F. J., Espinosa de los Monteros, K. and Arguelles, W. 2009. Resiliency in the face of disadvantage: Do Hispanic cultural characteristics protect health outcomes?. Journal of Personality, 77: 1707–1746. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) as a means of understanding disparities in health-related quality of life appraisals among Hispanic Americans. Questionnaire data were collected from 236 Hispanic participants, including measures of perceived discrimination, optimism, social support, symptoms of trait anxiety, and physical and mental health-related quality of life. Path analysis indicated direct, negative associations between perceived discrimination and both forms of health-related quality of life. Results also showed that these relationships were partially mediated by the reserve capacity variable of optimism and by symptoms of anxiety, though evidence for mediation by anxiety was stronger than for optimism. Findings suggest that perceived discrimination depletes intrapersonal reserves in Hispanic Americans, which, in turn, induces negative emotions. Implications for community-level interventions are discussed.     

Latent profile analysis of working memory capacity and thinking styles in adults and adolescents

This study of adults (n = 269) and adolescents (n = 308) applied latent profile analysis to preference for rational and/or experiential cognition, coupled with working memory capacity (WMC). A 4-profile solution comprising rationally dominant, experientially dominant, dual preference, and disengaged groups was retained for both adult and adolescent samples. Our solution indicated that high WMC was associated with both preference and ability to engage in rational processing. Profile membership significantly discriminated both adults and adolescents on several reasoning tasks and measures of cognitive biases. Overall our results indicate that cognitive processing styles and WMC can be combined to create a typology that distinguishes between four types of thinkers who significantly differ in their performance on reasoning tasks.     

Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference

Impairment on standard tests of delayed recall is often already maximal in the aMCI stage of Alzheimer's Disease. Neuropathological work shows that the neural substrates of memory function continue to deteriorate throughout the progression of the disease, hinting that further changes in memory performance could be tracked by a more sensitive test of delayed recall. Recent work shows that retention in aMCI patients can be raised well above floor when the delay period is devoid of further material - 'Minimal Interference'. This memory enhancement is thought to be the result of improved memory consolidation. Here we used the minimal interference/interference paradigm (word list retention following 10 min of quiet resting vs. picture naming) in a group of 17 AD patients, 25 aMCI patients and 25 controls. We found (1) that retention can be improved significantly by minimal interference in patients with aMCI and patients with mild to moderate AD; (2) that the minimal interference paradigm is sensitive to decline in memory function with disease severity, even when performance on standard tests has reached floor; and (3) that this paradigm can differentiate well (80% sensitivity and 100% specificity) between aMCI patients who progress and do not progress to AD within 2 years. Our findings support the notion that the early memory dysfunction in AD is associated with an increased susceptibility to memory interference and are suggestive of a gradual decline in consolidation capacity with disease progression.     

Examining Multi-Sector Community Collaboratives as Vehicles for Building Organizational Capacity

While community collaboratives have emerged as a prominent vehicle for fostering a more coordinated community response to complex issues, research to date suggests that the success of these efforts at achieving community/population-level improvements is mixed. As a result, researchers and practitioners are increasing their focus on the intermediate outcomes accomplished by these entities. The purpose of this study is to expand upon this examination of potential intermediate outcomes by investigating the ways in which collaboratives strengthen the capacity of the organizations who participate as members. Utilizing a mixed methods design, we present an empirically-based framework of organizational outcomes associated with participation in a community collaborative. The dimensions of this framework are validated based on quantitative findings from representatives of 614 different organizations and agencies nested within 51 different community collaboratives. This article then explores how the characteristics of organizations and their representatives relate to the nature and type of impacts associated with membership. Based on study findings, we argue that community collaboratives can be effective interventions for strengthening organizational capacity across all sectors in ways that can promote greater community resiliency.