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Kim H Tran,1,2 Andrew P McDonald,1,3 Ryan CN D’Arcy,2,3 Xiaowei Song1,2 1Clinical Research Centre, Surrey Memorial Hospital, Fraser Health Authority, Surrey, BC, Canada; 2Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada; 3Department of Medicine, University of British Columbia, Vancouver, BC, CanadaCorrespondence: Xiaowei Song 13750 96th Avenue, Surrey, BC V3V 1Z2, CanadaTel +1 604 585 5666 ext. 774 986Email xiaowei.song@fraserhealth.caAbstract: Contextual processing (or context processing; CP) is an integral component of cognition. CP allows people to manage their thoughts and actions by adjusting to surroundings. CP involves the formation of an internal representation of context in relation to the environment, maintenance of this information over a period of time, and the updating of mental representations to reflect changes in the environment. Each of these functions can be affected by aging and associated conditions. Here, we introduced contextual processing research and summarized the literature studying the impact of normal aging and neurodegeneration-related cognitive decline on CP. Through searching the PubMed, PsycINFO, and Google Scholar databases, 23 studies were retrieved that focused on the impact of aging, mild cogniitve impairment (MCI), Alzheimer’s disease (AD), and Parkinson’s disease (PD) on CP. Results indicated that CP is particularly vulnerable to aging and neurodegeneration. Older adults had a delayed onset and reduced amplitude of electrophysiological response to information detection, comparison, and execution. MCI patients demonstrated clear signs of impaired CP compared to normal aging. The only study on AD suggested a decreased proactive control in AD participants in maintaining contextual information, but seemingly intact reactive control. Studies on PD restricted to non-demented older participants, who showed limited ability to use contextual information in cognitive and motor processes, exhibiting impaired reactive control but more or less intact proactive control. These data suggest that the decline in CP with age is further impacted by accelerated aging and neurodegeneration, providing insights for improving intervention strategies. This review highlights the need for increased attention to research this important but understudied field.Keywords: Alzheimer’s disease, Parkinson’s disease, mild-cognitive impairment, aging, dementia, contextual processing, EEG-ERP, behavior

Mathias Schlögl,1 Michael F Holick21University Center for Medicine of Aging Basel, University of Basel, Basel, Switzerland; 2Department of Medicine, Section of Endocrinology, Nutrition, and Diabetes, Vitamin D, Skin, and Bone Research Laboratory, Boston University Medical Center, Boston, MA, USAAbstract: In recent years, emerging evidence has linked vitamin D not only to its known effects on calcium and bone metabolism, but also to many chronic illnesses involving neurocognitive decline. The importance of vitamin D3 in reducing the risk of these diseases continues to increase due to the fact that an increasing portion of the population in developed countries has a significant vitamin D deficiency. The older population is at an especially high risk for vitamin D deficiency due to the decreased cutaneous synthesis and dietary intake of vitamin D. Recent studies have confirmed an association between cognitive impairment, dementia, and vitamin D deficiency. There is a need for well-designed randomized trials to assess the benefits of vitamin D and lifestyle interventions in persons with mild cognitive impairment and dementia.Keywords: vitamin D, 25(OH)D level, cognition, mild cognitive impairment, Alzheimer's disease, vascular dementia