The 24-hour day is spent engaging in activities that include light-physical activity (LPA), moderate-vigorous physical activity (MVPA), sedentary time (i.e., sitting/lying/reclining posture with energy expenditure <1.5 METs, while awake), and sleep. These behaviors are mutually exclusive and time spent in one behavior affects the time spent in another. The time among these 24-hour behaviors is also associated with cardiometabolic health outcomes, including adiposity. Assessing specific behavioral contexts and their relationship within the 24-hour day is underdeveloped, this includes recreational sedentary screen time (rSST). rSST is sedentary time with televisions, computers, smartphones, tablets, inactive video games, and its relationship with other 24-hour behaviors is underdeveloped. This dissertation works evaluates the relationship between rSST and 24-hour behaviors, and adiposity in adults. The first study reviewed the existing observational and experimental evidence for rSST and its relationship with 24-hour behaviors by conducting a scoping review. From the 75 experimental and observational studies included, the evidence supported an overall positive association between rSST and non-screen sedentary behavior, an overall negative association between rSST with physical activity, and overall positive and negative associations between rSST with various sleep variables. The second study assessed the daily associations between rSST and 24-hour behaviors and how associations are influenced by age, sex, chronotype, and week- or weekend days. The findings include significant negative associations at between- and within-person levels for rSST with non-screen sedentary time, standing, LPA, MVPA, and sleep that were differentially influenced by age, chronotype, and week- or weekend day. The third study examined reallocating time between rSST and 24-hour behaviors and the associations with adiposity (i.e., body mass index, body fat percentage, and waist circumference). The results showed significant associations of replacing non-screen sedentary time with MVPA for both body fat percentage and waist circumference; and no significant associations between rSST and 24-hour behaviors for body mass index. Overall, this dissertation work provides important insights into the relationships between rSST and 24-hour behaviors and their relation to adiposity. These findings can be used to inform future intervention development targeting multiple behavior changes and improving health outcomes.

Falls are a public health concern for older adults with or without cognitive impairment, including clinical Mild Cognitive Impairment (MCI) and Alzheimer’s Disease (AD) dementia. Executive function (EF) is linked to falls and is notably impaired in individuals with MCI and AD dementia. However, it is unclear which EF assessments are associated with falls in older adults with intact cognition, MCI, and AD dementia. Apolipoprotein E4 (ApoE4) increases the risk of MCI and AD dementia, with limited information suggesting decreased EF and gait impairment in ApoE4 carriers. The purpose of this study was to 1) investigate the relationships between EF assessments and falls (fall history and future fall) by cognitive status (intact cognition, MCI, AD dementia) and 2) determine if ApoE4 moderates the relationship between EF and falls across cognitive status. EF assessments included Digit Span (DS), Trail Making Test (ΔTMT), Stroop Interference Test, Controlled Oral Word Association assessments of phonemic and semantic fluency (COWAC), and Clock Drawing Test. Binary logistic regression was used with secondary data to analyze the EF and falls relationship. Results showed a significant association of the ΔTMT with fall history but may not be appropriate for use with people with AD dementia due to a floor effect. Significant interaction effects were shown between AD dementia and DS, ΔTMT, and EF as a latent variable, where individuals with a fall history had better EF performance. The interaction effects are influenced by the lower percentage of reported falls in people with severe AD dementia. In the second aim, a confounding effect exposed a potential four-way interaction where higher EF in ApoE4 non-carriers with AD dementia experienced a future fall without a fall history. Overall, more research is needed to determine which EF assessments are best suited for fall risk assessment and whether ApoE4 plays a role in the relationship between EF and falls. Since the low percentage of reported falls in people with severe AD dementia exposed a differing trend between EF and falls, more research is needed to develop valid and reliable tools for collecting fall data in individuals with severe AD dementia.

Due to the enormous effect that dementia has on an individual’s behavior, spatial orientation, and wayfinding, among other things, an emphasis on resilience factors is imperative when designing an appropriate long-term care facility. Some resilience factors in improving quality of life for individuals with dementia include: walking spaces or physical activity, social integration, learning new skills, and support from family or caregivers. To increase these resilience factors and improve the quality of life of those living with dementia, the built environment plays a large role in the facilitation of each factor. For example, having open spaces that allow for families to interact with each other, outdoor space for physical activity or learning new skills, or an intuitive layout for lost individuals to find their way can greatly lessen distress and enhance a living environment. While some of these factors can be assessed from floor plans, understanding how the space is used and organized will further contribute to understanding how accessible and useful the care facilities are for those who inhabit them. Through the analysis of three long-term dementia care facilities, better practices to aid wayfinding, physical activity, and accessibility of the built environment with the ultimate goals of ensuring safety, promoting autonomy, and aiding a person’s adjustment to life in a long-term care facility.