Lifestyle activities, mental health and cognitive function in adults aged 50 to 90 years

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel UniversityIn a series of studies, lifestyle activities, mental health and aerobic fitness were investigated in relation to mean RT and response time variability (trial-to-trial variability in RT performance) obtained from a battery of cognitive measures in 257 healthy adults aged 50 to 90 years (M = 63.60). Cognition was assessed across four domains; psychomotor performance, executive function, visual search and word recognition. Hierarchical multiple regression analyses and structural equation modelling (SEM) were used to explore associations between age and outcome measures in a mediated-moderator analysis. The dedifferentiation of cognition and the dissociation between the outcome measures of mean RT and response time variability was also explored. Additionally, the neural correlates of response time variability were investigated using functional magnetic resonance imaging (fMRI). The findings indicated that poor mental health was associated with greater within-person (WP) variability and slower mean RTs and that this effect was greater in older adults. Higher lifestyle activity scores and higher aerobic fitness (VO2max) attenuated negative age gradients in WP variability and mean RT. Analyses suggested that the above effects were mediated by executive function. There was no evidence of dedifferentiation across cognitive domains and there was selective dissociation between the measures of mean RT and WP variability. The fMRI results suggested that WP variability was associated with fluctuations in executive control and, relatedly, attentional lapses. Overall, the findings suggest that executive function mediates a substantial portion of age-related variance in cognition and that this association is influenced by moderators such as an active lifestyle, aerobic fitness and mental health. The findings underline the potential benefits and importance of interventions to help maintain and promote mental health, and active lifestyles, in old age

Aerobic Fitness and Intraindividual Reaction Time Variability in Middle and Old Age.

Objective: To examine whether aerobic fitness moderated age differences in within-person reaction time variability (WP RT variability) and given conceptual linkage involving the frontal cortex, whether effects were mediated by executive function. Method: Aerobic fitness (estimated VO2max) and WP RT variability were investigated in 225 healthy, community-dwelling adults aged 50-90 years (M = 63.83) across 4 cognitive domains; psychomotor performance, executive function, visual search, and recognition. Results: Significant Age × Aerobic fitness interactions were found in relation to WP variability in 3 cognitive domains: psychomotor performance (4-choice RT), executive function (Flanker and Stroop arrows), and immediate recognition. Lower aerobic fitness was associated with greater RT variability, and this effect increased with age. Additionally, some of these effects were mediated by executive function. Discussion: The findings suggest that aerobic fitness moderated the association between age and intraindividual RT variability, and that executive function selectively mediated that association. It is possible that aerobic fitness helps attenuate the neurobiological decline that contributes to cognitive deficits in old age and that WP variability is a measure that may be particularly sensitive to this effect

A Longitudinal Analysis of Cumulative Risks, Cumulative Promotive Factors, and Adolescent Violent Behavior

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93547/1/jora786.pd

The impact of hearing impairment and hearing aid use on progression to mild cognitive impairment in cognitively healthy adults: An observational cohort study

INTRODUCTION: We assessed the association of self‐reported hearing impairment and hearing aid use with cognitive decline and progression to mild cognitive impairment (MCI). METHODS: We used a large referral‐based cohort of 4358 participants obtained from the National Alzheimer's Coordinating Center. The standard covariate‐adjusted Cox proportional hazards model, the marginal structural Cox model with inverse probability weighting, standardized Kaplan‐Meier curves, and linear mixed‐effects models were applied to test the hypotheses. RESULTS: Hearing impairment was associated with increased risk of MCI (standardized hazard ratio [HR] 2.58, 95% confidence interval [CI: 1.73 to 3.84], P = .004) and an accelerated rate of cognitive decline (P < .001). Hearing aid users were less likely to develop MCI than hearing‐impaired individuals who did not use a hearing aid (HR 0.47, 95% CI [0.29 to 0.74], P = .001). No difference in risk of MCI was observed between individuals with normal hearing and hearing‐impaired adults using hearing aids (HR 0.86, 95% CI [0.56 to 1.34], P = .51). DISCUSSION: Use of hearing aids may help mitigate cognitive decline associated with hearing loss

Dementias Platform UK (DPUK) Data Portal - supporting multi-modal data analysis, data linkage and real-world outcomes

DPUK relaunched the Data Portal in November 2017 to present openly available information on the data availability and technical capability of the Data Portal, which supports multi-modal research studies with various objectives from disease model validation to observation investigation. DPUK not only brings clinical data together from cohorts, but is now supporting multi-modal studies in genetics and imaging, as well as linkage opportunities to routine data using world-leading technical solutions to data sharing. The capacity, adaptability and sophistication of the UK Secure eResearch Platform which the Portal is housed on, allows for unprecedented levels of centralised access to rich cohort and routine data, which is consequentially leading to international collaboration and development ambition within epidemiology, bioinformatics, research methodology and technical research solutions. As of March 2018, DPUK is supporting 50 cohorts, 41 from the UK and 9 from across the rest of the world, alongside furthering links and access to routine data held in the UK and across the world. 20 research studies are underway, and the DPUK mission to enhance data science within dementia research is leading the conversation for developing a community of excellence in this field and across other research genres

Purpose and mastery as predictors of perceived health and substance use problems

We explored whether purpose in life and mastery predicted perceived physical health and problematic substance use among a sample of emerging adults who reported ever using alcohol or drugs. We examined perceived stress and coping as potential mediators of these associations and explored whether parental support moderated any of these associations. In a sample of emerging adults from across the United States (N = 2,564; Mage = 20.87, standard deviation = 1.75; 49.6% male), purpose in life and mastery were associated with better‐perceived health and fewer negative consequences of drug use via lower perceived stress and coping. In addition, parental support modified the relationship between purpose in life and stress and coping. The findings suggest potential health benefits associated with a greater purpose in life and mastery and indicate that parental support may enhance these associations.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150587/1/jcop22200_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150587/2/jcop22200.pd

Trajectories of organized activity participation among urban adolescents: Associations with young adult outcomes

Organized activity participation provides opportunities for adolescents to develop assets that may support favorable outcomes in young adulthood. Activity participation may be especially beneficial for marginalized youth because they are likely to face stressors that increase risk of negative outcomes. We used growth mixture modeling to identify activity participation trajectories among African American adolescents in an urban, disadvantaged community (Wave 1: mean age = 14.86 years, standard deviation = 0.64; 49% male, N = 681). We also investigated if young adult outcomes differed by participation trajectory subgroups, the results of which suggested that a 3‐class model best fit the data: low initial and decreasing levels of participation (74%); moderate initial and consistent (21%); and moderate initial and increasing (5%). Adolescents in the increasing class reported higher life satisfaction and lower substance use in young adulthood compared to the decreasing class. Youth who increase participation in activities over time may experience greater opportunities for building assets related to positive development that support health and well‐being into young adulthood.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136459/1/jcop21863.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136459/2/jcop21863_am.pd