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Just-in-time adaptive interventions (JITAIs) are time-varying adaptive interventions that use frequent opportunities for the intervention to be adapted-weekly, daily, or even many times a day. The microrandomized trial (MRT) has emerged for use in informing the construction of JITAIs. MRTs can be used to address research questions about whether and under what circumstances JITAI components are effective, with the ultimate objective of developing effective and efficient JITAI. The purpose of this article is to clarify why, when, and how to use MRTs; to highlight elements that must be considered when designing and implementing an MRT; and to review primary and secondary analyses methods for MRTs. We briefly review key elements of JITAIs and discuss a variety of considerations that go into planning and designing an MRT. We provide a definition of causal excursion effects suitable for use in primary and secondary analyses of MRT data to inform JITAI development. We review the weighted and centered least-squares (WCLS) estimator which provides consistent causal excursion effect estimators from MRT data. We describe how the WCLS estimator along with associated test statistics can be obtained using standard statistical software such as R (R Core Team, 2019). Throughout we illustrate the MRT design and analyses using the HeartSteps MRT, for developing a JITAI to increase physical activity among sedentary individuals. We supplement the HeartSteps MRT with two other MRTs, SARA and BariFit, each of which highlights different research questions that can be addressed using the MRT and experimental design considerations that might arise. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Despite widespread interest in variance in affect, basic questions remain pertaining to the relative proportions of between-person and within-person variance, the contribution of days and moments, and the reliability of these estimates. We addressed these questions by decomposing negative affect and positive affect variance across three levels (person, day, moment), and calculating reliability using a coordinated analysis of seven daily diary, ecological momentary assessment (EMA), and diary-EMA hybrid studies (across studies age = 18-84 years, total Npersons = 2,103, total Nobservations = 45,065). Across studies, within-person variance was sizeable (negative affect: 45% to 66%, positive affect: 25% to 74%); in EMA more within-person variance was attributable to momentary rather than daily level. Reliability was adequate to high at all levels of analysis (within-person: .73-.91; between-person: .96-1.00) despite different items and designs. We discuss the implications of these results for the design of future intensive studies of affect variance.

Although stress is a common experience in everyday life, a clear understanding of how often an individual experiences and reports stress is lacking. Notably, there is little information regarding factors that may influence how frequently stress is reported, including which stress dimension is measured (i.e., stressors-did an event happen, subjective stress-how stressed do you feel, conditional stress-how stressful a stressor was) and the temporal features of that assessment (i.e., time of day, day of study, weekday vs. weekend day). The purpose of the present study was to conduct a coordinated analysis of five independent ecological momentary assessment studies utilizing varied stress reporting dimensions and temporal features. Results indicated that, within days, stress was reported at different frequencies depending on the stress dimension. Stressors were reported on 15-32% of momentary reports made within a day; across days, the frequency ranged from 42 to 76% of days. Depending on the cutoff, subjective stress was reported more frequently ranging about 8-56% of all moments within days, and 40-90% of days. Likewise, conditional stress ranged from just 3% of moments to 22%, and 11-69% of days. For the temporal features, stress was reported more frequently on weekdays (compared to weekend days) and on days earlier in the study (relative to days later in the study); time of day was inconsistently related to stress reports. In sum, stress report frequency depends in part on how stress is assessed. As such, researchers may wish to measure stress in multiple ways and, in the case of subjective and conditional stress with multiple operational definitions, to thoroughly characterize the frequency of stress reporting.

Advancing age is often characterized by preserved or even enhanced emotion regulation, which is thought to manifest in terms of age-related reductions in the within-person association between stressors and negative affect. Existing research from ecological momentary assessment and end-of-day daily diary studies examining such age-related benefits have yielded mixed results, potentially due to differences in samples, design, and measurement of everyday stressors and negative affect. We conducted a coordinated analysis of 5 ecological momentary assessments and 2 end-of-day daily diary studies to examine adult age differences in the within-person association between everyday stressors and negative affect. Reported stressor occurrences are robustly associated with higher negative affect, regardless of study design and sample characteristics. Across studies, interactions between age and everyday stressors predicting negative affect revealed a pattern of age-related decreases in the stressor-negative affect association, but this interaction was only significant for 2 studies. Further, examination of statistical power of the included studies suggests that, despite differences in the number of repeated assessments, power to detect within-person stressor-negative affect associations is quite good. In contrast, despite possessing wider age ranges, observed age differences were relatively small in magnitude, and studies are potentially underpowered to detect age differences in these within-person associations. We discuss the importance of study design, interval of repeated assessments and number of participants for examining age differences in everyday stressors and negative affect, as well as the virtue of coordinated analyses for detecting consistent direction of associations, but inconsistent patterns of statistical significance. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Antisocial peer behavior and low parental knowledge of adolescents' activities are key interpersonal risk factors for adolescent substance use. However, how the magnitude of associations between these risk factors and substance use may vary across adolescence remains less well understood. The present study examined the age-varying associations of parental knowledge and antisocial peer behavior with adolescents' substance use (i.e., cigarette use, drunkenness, and marijuana use) using time-varying effect modeling. Using data from the Promoting School-Community-University Partnerships to Enhance Resilience (PROSPER) study, the final sample consists of 8,222 adolescents, followed from Grade 6 to Grade 12 (age 11 to age 18.9), including those who newly joined the schools at the targeted grade levels. Results showed that low parental knowledge and antisocial peer behavior were significantly associated with the use of each of the three substances across the majority of adolescence. The magnitude of the associations between substance use and both risk factors decreased across age, except between peer risk and marijuana use. Further, there was a significant interaction between parent and peer risk factors such that low parental knowledge was less strongly associated with substance use at higher levels of antisocial peer behavior. Findings highlighted early adolescence as an important period to target parent and peer prevention and interventions for reducing early substance use.

Stress is an established risk factor for negative health outcomes, and responses to everyday stress can interfere with health behaviors such as exercise and sleep. In accordance with the Science of Behavior Change (SOBC) program, we apply an experimental medicine approach to identifying stress response targets, developing stress response assays, intervening upon these targets, and testing intervention effectiveness. We evaluate an ecologically valid, within-person approach to measuring the deleterious effects of everyday stress on physical activity and sleep patterns, examining multiple stress response components (i.e., stress reactivity, stress recovery, and stress pile-up) as indexed by two key response indicators (negative affect and perseverative cognition). Our everyday stress response assay thus measures multiple malleable stress response targets that putatively shape daily health behaviors (physical activity and sleep). We hypothesize that larger reactivity, incomplete recovery, and more frequent stress responses (pile-up) will negatively impact health behavior enactment in daily life. We will identify stress-related reactivity, recovery, and response in the indicators using coordinated analyses across multiple naturalistic studies. These results are the basis for developing a new stress assay and replicating the initial findings in a new sample. This approach will advance our understanding of how specific aspects of everyday stress responses influence health behaviors, and can be used to develop and test an innovative ambulatory intervention for stress reduction in daily life to enhance health behaviors.

We examined the prevalence of psychological outcomes (i.e., symptoms of depression and anxiety) by age and age-varying associations between physical activity and psychological outcomes among rural cancer survivors. Participants (N = 219; ages 22-93) completed sociodemographic, psychological, and physical activity questionnaires. Time-varying effect models estimated the prevalence of psychological outcomes and assessed associations between physical activity and psychological outcomes as a flexible function of age. Depression and anxiety symptoms decreased with age among cancer survivors aged 22-40 years and were relatively stable across age among those > 40 years. Positive associations between vigorous physical activity and psychological outcomes in those aged 22-40 years were identified. In those > 70-80 years, there were negative associations between vigorous physical activity and psychological outcomes. Results suggest there is variation across age in the associations between physical activity and psychological outcomes among rural survivors. Future research should further explore these age-varying relationships to identify important intervention targets., Author(s): Nishat Bhuiyan [sup.1] , Ashley N. Linden-Carmichael [sup.3] , Stephanie T. Lanza [sup.2] [sup.3] , Kathryn H. Schmitz [sup.4] , Scherezade K. Mama [sup.1] [sup.5] Author Affiliations: (1) grid.29857.31, [...]

Although alcohol use is related to daily affect, findings regarding affect variability—the degree to which individuals exhibit day-to-day fluctuations in affect—and alcohol use have been mixed. The present study assessed whether individuals who use alcohol tend to have higher positive and negative affect variability than individuals who do not, as well as whether higher affect variability is related to more frequent and intense alcohol use among individuals who use alcohol. We also explored whether affect variability differed between individuals who use alcohol and those who concurrently use alcohol and cannabis. College students (N = 1909; M = 20.1, SD = 1.3; 67.7% female; 76.6% white; n = 1147 individuals who use alcohol) completed a 21-day protocol between February-December 2021 in which they reported daily affect, number of drinks consumed, and any cannabis use. As hypothesized, individuals who used alcohol had higher positive and negative affect variability than individuals who did not. Among individuals who used alcohol, individuals with higher negative affect variability drank alcohol more frequently, and both higher positive and negative affect variability were related to more intense alcohol use. No differences emerged between individuals who used alcohol and those who concurrently used alcohol and cannabis. Taken together, higher positive and negative affect variability were related to higher odds of using alcohol and more frequent and intense use among individuals who use alcohol, over and above average affect. Higher affect variability could relate to alcohol use because of difficulties with emotion regulation or heightened sensitivity to the environment. [ABSTRACT FROM AUTHOR]

The aims of the current study were threefold: (1) specify the skills component of social influence prevention interventions for preadolescents, (2) examine the relationship between resistance skill profiles and substance use among preadolescents, and (3) evaluate whether subgroups of preadolescents based on their resistance skills and refusal confidence may be differentially impacted by the kiR prevention program. Latent class analysis showed a four-class model of 5th grader resistance skill profiles. Approximately half of preadolescents (53%) were familiar with four prototypical resistance skills and showed confidence to apply these skills in real-world settings (highly competent profile); 15% were familiar with resistance skills but had little confidence (skillful profile); 18% were confident yet had little knowledge (confident profile); while 15% had low knowledge and confidence (low competence profile). These skill profiles significantly predicted 8th grade recent substance use (2LL = -2,262.21, df = 3, p = .0005). As predicted by theory, the highly competent skill profile reported lower mean recent substance use than the population sample mean use. Latent transition analysis showed that although patterns of transiting into the highly competent skill profile over time were observed in the expected direction, this pattern was not significant when comparing treatment and control. Identifying skill profiles that predict recent substance use is theoretically consistent and has important implications for healthy and substance-free development.

BackgroundMobile technology has increased the reach of health behavior interventions but raised new challenges in assessing the fidelity of treatment receipt. Fidelity can be compromised if participant fatigue or burden reduces engagement, leading to missed or delayed treatments for just-in-time interventions. ObjectiveThis study aimed to investigate the temporal dynamics of text message receipt confirmations. MethodsCommunity-dwelling adults (N=10) were sent five text messages daily for 4 months (5598 messages sent in total), with a financial incentive to confirm receipt of 75% or more messages. ResultsOverall, the message receipt confirmation rate was very high (5504/5598, 98.32%) and timely (eg, two-thirds of confirmations within 2 min). Confirmation times were slightly slower on weekends (vs weekdays) and as a function of the cumulative time in the study. Neither time of message delivery nor message content was associated with message confirmation latencies. ConclusionsParticipants receiving financial incentives to confirm text message receipt exhibit extremely high and fast confirmation rates, although receipt confirmations were somewhat less timely on weekends (vs weekdays) and later in the intervention. The social calendar and treatment fatigue should be considered when planning text message–based interventions, especially if treatments are intended for a just-in-time delivery that requires extended engagement and precise timing.

Time-varying effect modeling (TVEM), a statistical technique for modeling dynamic patterns of change, presents new opportunities to study biobehavioral health processes. TVEM is particularly useful when applied to intensive longitudinal data (ILD) because it permits highly flexible modeling of outcomes over continuous time, as well as of associations between variables and moderation effects. TVEM coupled with ILD is ideal for the study of addiction. This article provides a general overview of using TVEM, particularly when applied to ILD, to better enable addiction scientists to conduct novel analyses that are important to realizing the dynamics of addiction-related processes. It presents an empirical example using ecological momentary assessment data from participants throughout their first 90 days of addiction recovery to estimate the (1) associations between morning craving and same-day recovery outcomes, (2) association between morning positive and negative affect and same-day recovery outcomes and (3) time-varying moderation effects of affect on the association between morning craving and recovery outcomes.We provide a didactic overview in implementing and interpreting the aims and results, including equations, computer syntax and reference resources. Our results highlight how affect operates as both a time-varying risk and protective factor on recovery outcomes, particularly when considered in combination with experiences of craving (i.e. dynamic moderation). We conclude by discussing our results, recent innovations and future directions of TVEM for advancing addiction science, including how 'time' can be operationalized to probe new research questions. [ABSTRACT FROM AUTHOR]