The significance of levels of organization for scientific research: A heuristic approach

Demand Coupling Drives Neurodegeneration: A Model of Age-Related Cognitive Decline and Dementia

The societal burden of Alzheimer's Disease (AD) and other major forms of dementia continues to grow, and multiple pharmacological agents directed towards modifying the pathological "hallmarks" of AD have yielded disappointing results. Though efforts continue towards broadening and deepening our knowledge and understanding of the mechanistic and neuropathological underpinnings of AD, our previous failures motivate a re-examination of how we conceptualize AD pathology and progression. In addition to not yielding effective treatments, the phenotypically heterogeneous biological processes that have been the primary area of focus to date have not been adequately shown to be necessary or sufficient to explain the risk and progression of AD. On the other hand, a growing body of evidence indicates that lifestyle and environment represent the ultimate level of causation for AD and age-related cognitive decline. Specifically, the decline in cognitive demands over the lifespan plays a central role in driving the structural and functional deteriorations of the brain. In the absence of adequate cognitive stimulus, physiological demand-function coupling leads to downregulation of growth, repair, and homeostatic processes, resulting in deteriorating brain tissue health, function, and capacity. In this setting, the heterogeneity of associated neuropathological tissue hallmarks then occurs as a consequence of an individual's genetic and environmental background and are best considered downstream markers of the disease process rather than specific targets for direct intervention. In this manuscript we outline the evidence for a demand-driven model of age-related cognitive decline and dementia and why it mandates a holistic approach to dementia treatment and prevention that incorporates the primary upstream role of cognitive demand.

The levels problem in psychopathology

Psychiatric disorders are studied at multiple levels, but there is no agreement on how these levels are related to each other, or how they should be understood in the first place. In this paper, I provide an account of levels and their relationships that is suited for psychopathology, drawing from recent debates in philosophy of science. Instead of metaphysical issues, the focus is on delivering an understanding of levels that is relevant and useful for scientific practice. I also defend a pragmatic approach to the question of reduction, arguing that even in-principle reductionists should embrace pluralism in practice. Finally, I discuss the benefits and challenges in integrating explanations and models of different levels.

Organising Levels of Organisation for Biology Education: A Systematic Review of Literature

Many authors suggest an explicit reflection on the levels of organisation, based on known difficulties related to understanding biological systems. Yet, there is no scientific consensus on the characteristics of biological levels and the quality of their relationships. This review intends to present the state of the current discussion in order to establish an educational argumentation as a basis for the development of learning environments and teaching experiments in biology education. For this purpose, we conducted a systematic literature review. Three databases (BIOSIS, ERIC, Fachportal-Pädagogik) were searched for literature on levels of organisation. The papers were analysed by means of a qualitative content analysis based on the following research questions: (1) Which levels of organisation do the authors name? (2) How do the authors describe the levels of organisation? (3) How do the authors describe the relationship between different levels of organisation? (4) How do the authors describe the challenges of these levels for biological education? (5) How do the authors describe the benefit of these levels for biological education? Based on the results, we propose a system of levels that features the concept of zooming-in and makes the relationships between the levels explicit.