Matching Items (58)
Description
Psychologists report effect sizes in randomized controlled trials to facilitate interpretation and inform clinical or policy guidance. Since commonly used effect size measures (e.g., standardized mean difference) are not sensitive to heterogeneous treatment effects, methodologists have suggested the use of an alternative effect size δ, a between-subjects causal parameter describing the probability that the outcome of a random participant in the treatment group is better than the outcome of another random participant in the control group. Although this effect size is useful, researchers could mistakenly use δ to describe its within-subject analogue, ψ, the probability that an individual will do better under the treatment than the control. Hand’s paradox describes the situation where ψ and δ are on opposing sides of 0.5: δ may imply most are helped whereas the (unknown) underlying ψ indicates that most are harmed by the treatment. The current study used Monte Carlo simulations to investigate plausible situations under which Hand’s paradox does and does not occur, tracked the magnitude of the discrepancy between ψ and δ, and explored whether the size of the discrepancy could be reduced with a relevant covariate. The findings suggested that although the paradox should not occur under bivariate normal data conditions in the population, there could be sample cases with the paradox. The magnitude of the discrepancy between ψ and δ depended on both the size of the average treatment effect and the underlying correlation between the potential outcomes, ρ. Smaller effects led to larger discrepancies when ρ < 0 and ρ = 1, whereas larger effects led to larger discrepancies when 0 < ρ < 1. It was useful to consider a relevant covariate when calculating ψ and δ. Although ψ and δ were still discrepant within covariate levels, results indicated that conditioning upon relevant covariates is still useful in describing heterogeneous treatment effects.
ContributorsLiu, Xinran (Author) / Anderson, Samantha F (Thesis advisor) / McNeish, Daniel (Committee member) / MacKinnon, David (Committee member) / Arizona State University (Publisher)
Created2023
Description
Mediation analysis is integral to psychology, investigating human behavior’s causal mechanisms. The diversity of explanations for human behavior has implications for the estimation and interpretation of statistical mediation models. Individuals can have similar observed outcomes while undergoing different causal processes or different observed outcomes while receiving the same treatment. Researchers can employ diverse strategies when studying individual differences in multiple mediation pathways, including individual fit measures and analysis of residuals. This dissertation investigates the use of individual residuals and fit measures to identify individual differences in multiple mediation pathways. More specifically, this study focuses on mediation model residuals in a heterogeneous population in which some people experience indirect effects through one mediator and others experience indirect effects through a different mediator. A simulation study investigates 162 conditions defined by effect size and sample size for three proposed methods: residual differences, delta z, and generalized Cook’s distance. Results indicate that analogs of Type 1 error rates are generally acceptable for the method of residual differences, but statistical power is limited. Likewise, neither delta z nor gCd could reliably distinguish between contrasts that had true effects and those that did not. The outcomes of this study reveal the potential for statistical measures of individual mediation. However, limitations related to unequal subpopulation variances, multiple dependent variables, the inherent relationship between direct effects and unestimated indirect effects, and minimal contrast effects require more research to develop a simple method that researchers can use on single data sets.
ContributorsSmyth, Heather Lynn (Author) / MacKinnon, David (Thesis advisor) / Tein, Jenn-Yun (Committee member) / McNeish, Daniel (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2022
Description
This thesis attempts to use psychoneuroimmunology (PNI) as a lens for examining different immune and autoimmune disorders, as well as psychological function and dysfunction. Through this examination, it is hypothesized that PNI could point to an accurate theoretical framework for describing the mind-body relation, or at the very least gain a deeper respect for showing the complexity of consciousness and health. Conversely, an appropriate view of the mind-body relation should provide a sound theoretical framework for PNI research.
ContributorsJording, Colten (Author) / Hoffman, Steven (Thesis director) / Robert, Jason (Committee member) / Lewis, Candace (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2023-05
Description
Chronic pain, or reoccurring pain lasting longer than three months, is frequently co- morbid with other chronic conditions. Physiological health problems such as overall general health, immune function, inflammation, stress, and sleep, as well as psychological problems like depression and anxiety are all associated with chronic pain. Previous studies have also shown evidence for the heritability of chronic pain, indicating a genetic factor for chronic pain in children. However, few studies have investigated potential epigenetic processes involved in childhood chronic pain. DNA methylation and other epigenetic processes are highly susceptible to changes during crucial developmental periods in children, and they are heavily influenced by psychosocial factors and environmental factors. During an immune response, various cytokines such as TNFα, IL-6, and CRP are released. Cytokines are involved in the production of pain through their pro-inflammatory properties. Additionally, there is evidence to believe they increase pain sensitivity acutely by acting directly on nociceptors. Previous studies have shown that higher levels of inflammatory cytokines are associated with more pain because the inflammatory response from our immune cells activates pain pathways. A constant or prolonged activation of the immune response may consequently result in chronic pain. In many cases of chronic pain, there is an increase in the circulating pro-inflammatory cytokines in the blood that also leads to hypersensitivity.
ContributorsBaca, Itzahiana (Author) / Lewis, Candace (Thesis director) / Gewirtz, Jonathan (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2023-05
Description
ABSTRACTAutism spectrum disorder (ASD) is a neurodevelopmental condition associated with social communication challenges and restrictive and repetitive behaviors [2]. Despite known lifelong challenges, understanding of cognitive and brain aging with ASD is lacking. Middle-aged adults with ASD have a higher chance of developing Alzheimer’s disease (Alz) and other dementias compared to neurotypical (NT) adults [12].
Apolipoprotein E (APOE) is a lipid transport protein involved in neuronal repair and cholesterol transport and is the strongest genetic risk factor for Alz [22]. Others demonstrated that individuals with ASD are more likely to carry the APOE ε4-allele [21]. This study aimed to determine if the APOE ε4-allele negatively impacts verbal learning and memory in ASD compared to NT adults.
Participants were intellectually able 76 middle-age and older adults (MA+) between the ages of 40-71, including 35 with ASD [mean age=53.06 (±8.91)] and 41 NT adults [mean age=53.90 (±8.44)]. APOE allelic distribution was determined from salivary samples via polymerase chain reaction amplification and genotyped on a tapestation. The Auditory Verbal Learning Test (AVLT) variables were short-term memory, long-term memory, and total learning.
There was a main effect of APOE ε4 for short-term memory and verbal learning, with ε4 carriers performing worse across diagnosis groups. For verbal learning, sex was a significant predictor. So, exploratory analyses separating diagnosis groups by sex were conducted. Only males with ASD were found to be carrying APOE ε4 associated with reduced verbal learning (p=0.02). Finally, the APOE ε4-allele did not significantly affect the participants’ long-term memory.
These findings suggest that the APOE ε4-allele negatively impacts short-term memory and verbal learning in MA+ adults, and that autistic men may be particularly vulnerable to the effects of APOE ε4 on verbal learning. This study is the first to incorporate ASD in APOE’s association with cognition and investigate how sex differences impact memory function. Future research is needed to replicate these findings using a larger sample size to further understand how the ε4-allele affects memory function trajectories in MA+ ASD as they grow older.
ContributorsAl-Hassan, Lamees (Author) / Braden, Blair (Thesis advisor) / Lewis, Candace (Committee member) / Rogalsky, Corianne (Committee member) / Arizona State University (Publisher)
Created2023
Description
The emotional enhancement of memory (EEM) has consistently suggested that memory performance is enhanced for positively and negatively valenced stimuli. Heightened arousal and activation of the noradrenergic system facilitates encoding and the formation of memory traces. However, this EEM can become maladaptive when coupled with the heightened noradrenergic activity associated with posttraumatic stress disorder (PTSD). This heightened noradrenergic response can result in chronic intrusive memories of past traumatic events. This study aims to explore overall recall, retrieval dynamics, output editing, and intrusions as a function of emotional content and prior history with traumatic experiences. Undergraduate students (N=249) from Arizona State University completed a battery surveys measuring PTSD symptomatology and other related constructs including anxiety, depression, and trauma. Participants then completed a memory task, an externalized free recall task for multiple study-blocks utilizing word list stimuli. During recall, participants were instructed to report every word that came to mind regardless of whether it was present or not in the most recent study-block, then make a judgment about recent-list membership. Main effects of valence were found for recall accuracy, intrusion generation, and successful editing. This suggests that the emotional enhancement of memory does in fact play a role in intrusion generation and the ability to edit out false recollections. Only depression levels resulted in a significant interaction effect with valence, specifically when measuring intrusion generation. This suggests that trauma level does not play a significant role in emotional intrusion memory.
ContributorsDziendziel, Hailey K (Author) / Brewer, Gene A (Thesis advisor) / Azuma, Tamiko (Committee member) / Lewis, Candace (Committee member) / Arizona State University (Publisher)
Created2023
Description
Food insecurity is an economic and social condition involving limited or uncertain access to food. The problem of food insecurity in communities is influenced by economic conditions, food deserts, and barriers to accessing healthy food. Individuals experiencing food insecurity often endure concurrent problems of financial instability, hunger, and poor mental and physical health. Public and non-profit services in the U.S., such as the federally supported Supplemental Nutrition Assistance Program (SNAP) and community food banks, provide food-related assistance to individuals who are at a high risk of experiencing food insecurity. Unfortunately, many individuals who qualify for these services still experience food insecurity due to barriers preventing them from accessing food, which may include inadequate finances, transportation, skills, and information. Effective approaches for removing barriers that prevent individuals from accessing food are needed to mitigate the increased risk of hunger, nutritional deficiencies, and chronic disease among vulnerable populations. This dissertation tested a novel food insecurity intervention using informational nudges to promote food security through the elimination of information barriers to accessing food. The intervention used in this mixed-methods feasibility study consisted of informational nudges in the form of weekly text messages that were sent to food pantry clients experiencing food insecurity. The study aims were to test the efficacy and acceptability of the intervention by examining whether the informational nudges could enhance food pantry utilization, increase SNAP registration, and promote food security. Quantitative study results showed a lower prevalence of food insecurity in the intervention group than the control group. Qualitative findings revealed how the intervention group found the text messages to be helpful and informative. These study findings can enhance future food insecurity interventions aiming to eliminate barriers that prevent individuals who are food insecure from accessing healthy food.
ContributorsRoyer, Michael F. (Author) / Wharton, Christopher (Thesis advisor) / Buman, Matthew (Committee member) / Der Ananian, Cheryl (Committee member) / MacKinnon, David (Committee member) / Ohri-Vachaspati, Punam (Committee member) / Arizona State University (Publisher)
Created2023
Description
For my thesis, I conducted a study on a healthy pediatric cohort to investigate how DNA methylation of genes related to myelin may predict total white matter volume in a healthy pediatric cohort. The relatively new field of neuroimaging epigenetics investigates how methylation of genes in peripheral tissue samples is related to certain structural or functional features of the brain, as measured by neuroimaging data. Research has already demonstrated that methylation of genes in peripheral tissues is related to a variety of brain disorders. We hypothesized that methylation of myelin-related genes as measured in saliva samples would predict total white matter volume in a healthy pediatric cohort. After processing DNA methylation data from saliva samples from participants, multiple linear regressions were ran to determine if DNA methylation of myelin related genes was related to total white matter volume, as measured by data from structural MRIs. Results showed that these genes, which included MOG, MBP, and MYRF, significantly predicted total white matter volume. Two genes that were significant in our results have been previously shown to produce proteins that are essential to the structure of myelin.
ContributorsSpencer, Sophie (Author) / Lewis, Candace (Thesis director) / Braden, Blair (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / College of Integrative Sciences and Arts (Contributor)
Created2023-05
Description
Longitudinal recursive partitioning (LRP) is a tree-based method for longitudinal data. It takes a sample of individuals that were each measured repeatedly across time, and it splits them based on a set of covariates such that individuals with similar trajectories become grouped together into nodes. LRP does this by fitting a mixed-effects model to each node every time that it becomes partitioned and extracting the deviance, which is the measure of node purity. LRP is implemented using the classification and regression tree algorithm, which suffers from a variable selection bias and does not guarantee reaching a global optimum. Additionally, fitting mixed-effects models to each potential split only to extract the deviance and discard the rest of the information is a computationally intensive procedure. Therefore, in this dissertation, I address the high computational demand, variable selection bias, and local optimum solution. I propose three approximation methods that reduce the computational demand of LRP, and at the same time, allow for a straightforward extension to recursive partitioning algorithms that do not have a variable selection bias and can reach the global optimum solution. In the three proposed approximations, a mixed-effects model is fit to the full data, and the growth curve coefficients for each individual are extracted. Then, (1) a principal component analysis is fit to the set of coefficients and the principal component score is extracted for each individual, (2) a one-factor model is fit to the coefficients and the factor score is extracted, or (3) the coefficients are summed. The three methods result in each individual having a single score that represents the growth curve trajectory. Therefore, now that the outcome is a single score for each individual, any tree-based method may be used for partitioning the data and group the individuals together. Once the individuals are assigned to their final nodes, a mixed-effects model is fit to each terminal node with the individuals belonging to it.
I conduct a simulation study, where I show that the approximation methods achieve the goals proposed while maintaining a similar level of out-of-sample prediction accuracy as LRP. I then illustrate and compare the methods using an applied data.
I conduct a simulation study, where I show that the approximation methods achieve the goals proposed while maintaining a similar level of out-of-sample prediction accuracy as LRP. I then illustrate and compare the methods using an applied data.
ContributorsStegmann, Gabriela (Author) / Grimm, Kevin (Thesis advisor) / Edwards, Michael (Committee member) / MacKinnon, David (Committee member) / McNeish, Daniel (Committee member) / Arizona State University (Publisher)
Created2019
Description
There is a need to reinvent evidence-based interventions (EBIs) for pediatric anxiety problems to better address the demands of real-word service delivery settings and achieve public health impact. The time- and resource-intensive nature of most EBIs for youth anxiety has frequently been noted as a barrier to the utilization of EBIs in community settings, leading to increased attention towards exploring the viability of briefer, more accessible protocols. Principally, this research reports between-group effect sizes from brief-interventions targeting pediatric anxiety and classifies each as well-established, probably efficacious, possibly efficacious, experimental, or questionable. brief interventions yielded an overall mean effect size of 0.19 on pediatric anxiety outcomes from pre to post. Effect sizes varied significantly by level of intervention: Pre to post-intervention effects were strongest for brief-treatments (0.35), followed by brief-targeted prevention (0.22), and weakest for brief-universal prevention (0.09). No participant or other intervention characteristic emerged as significant moderators of effect sizes. In terms of standard of evidence, one brief intervention is well-established, and five are probably efficacious, with most drawing on cognitive and behavioral change procedures and/or family systems models. At this juncture, the minimal intervention needed for clinical change in pediatric anxiety points to in-vivo exposures for specific phobias (~3 hours), cognitive-behavioral therapy (CBT) with social skills training (~3 hours), and CBT based parent training (~6 hours, eight digital modules with clinician support). This research concludes with a discussion on limitations to available brief EBIs, practice guidelines, and future research needed to capitalize on the viability of briefer protocols in enhancing access to, and impact of, evidence-based care in the real-world.
ContributorsStoll, Ryan (Author) / Pina, Armando A. (Thesis advisor) / Gonzales, Nancy (Committee member) / MacKinnon, David (Committee member) / Perez, Marisol (Committee member) / Arizona State University (Publisher)
Created2019