Biomedical subjects

T E Duncan

Publications and source records attributed to T E Duncan.

At least 19 recordsLinked to original sources

PubMed2001

Tai Chi, self-efficacy, and physical function in the elderly.

Using Tai Chi as an exercise mode, this study examined the association between self-efficacy and physical function. Ninety-four healthy, physically inactive older adults (M age = 72.8 years, SD = 5.1) were randomly assigned to either a 6-month, twice a week, Tai Chi condition or a wait-list control condition. Outcome variables included self-reports of movement efficacy and physical function assessed at baseline, middle, and termination of the study. Multisample latent curve analyses revealed a significant rate of change attributable to the Tai Chi intervention in both self-efficacy and physical function, with participants experiencing significant improvements over the course of the intervention. Analyses also showed a positive association between self-efficacy and physical function, indicating that improvements in older adults' self-efficacy of movement as a function of Tai Chi were related to increased levels of perceived physical capability. This study uncovered the need for further exploration of the relationship between exercise self-efficacy and physical function for enhancing health-related quality of life in older adults.

Activities of Daily Living↗

PubMed2001

An evaluation of the effects of Tai Chi exercise on physical function among older persons: a randomized contolled trial.

This study was designed to determine whether a 6-month Tai Chi exercise program can improve self-reported physical functioning limitations among healthy, physically inactive older individuals. Ninety-four community residents ages 65 to 96 (Mage = 72.8 years, SD = 5.1) volunteered to participate in the study. Participants were randomly assigned to either a 6-month experimental (Tai Chi) group (n = 49), which exercised twice per week for 60 min, or a wait-list control group (n = 45). A 6-item self-report physical functioning scale, assessing the extent of behavioral dysfunction caused by health problems, was used to evaluate change in physical functioning limitations as a result of Tai Chi intervention. Results indicated that compared to the control group, participants in the Tai Chi group experienced significant improvements in all aspects of physical functioning over the course of the 6-month intervention. Overall, the experimental group had 65% improvement across all 6 functional status measures ranging from daily activities such as walking and lifting to moderate-vigorous activities such as running. It was concluded that the 6-month Tai Chi exercise program was effective for improving functional status in healthy, physically inactive older adults. A self-paced and self-controlled activity such as Tai Chi has thepotential to be an effective, low-cost means of improving functional status in older persons.

Activities of Daily Living↗

PubMed2001

Examining developmental trajectories in adolescent alcohol use using piecewise growth mixture modeling analysis.

OBJECTIVE: This study examined issues of heterogeneity in multiple stage development as it corresponds to qualitatively different developmental trajectories in alcohol use during adolescence. METHOD: Using a piecewise growth mixture modeling methodology, a two-piece growth model capturing growth trajectories in adolescent alcohol use from middle school (Grades 6 through 8) to high school (Grades 9 through 12) was examined (N = 179; 54% male). It was hypothesized that (1) two stages of alcohol use development with varying trajectories would exist in these data (the first corresponding to development during middle school, followed by a second stage of continuing growth during high school) and (2) there would be multiple growth trajectories (subgroups) of alcohol use in the stage-wise development, with varying effects in initial alcohol use and growth rates of alcohol use. RESULTS: Results indicated the tenability of the two-piece growth model of alcohol use with heterogeneity in the population comprising two distinct latent developmental trajectory classes. Class 1, with a high initial status of alcohol use at Grade 6, showed an upward increase in trajectory only during high school. Class 2, with a low initial status of alcohol use at Grade 6, showed a linear increase in middle school with a second growth spurt at high school entry and continuity in growth throughout the high school years. Analyses, incorporating time-invariate covariates, indicated varying influences of gender, early levels of deviant behavior, family structure (single vs two parent), peer encouragement and parent disapproval of alcohol use, and adolescent deviant behavior upon high school entry, on the two trajectory classes. Results also showed effects of the identified trajectories, with varying magnitudes, on later substance use in young adulthood, with Class 1 showing the strongest continuity in later substance use. CONCLUSIONS: Findings suggest heterogenous development of alcohol use in the adolescent population, associated with varying background and covariate influences. In addition, this heterogeneity is linked to alcohol and other substance use in young adulthood.

Adolescent↗

PubMed2000

Risk and protective factors influencing adolescent problem behavior: a multivariate latent growth curve analysis.

This study examined the dynamic relations between adolescent problem behaviors (alcohol, marijuana, deviance, academic failure) over time and predictors of these behaviors. Data from the National Youth Survey (1) included 1,044 adolescents (53.5% male; mean age at year 1 = 13.20). Dependent measures were adolescent alcohol use, marijuana use, deviance, and academic failure, assessed annually over 4 years. Independent measures included age, gender, marital status, income, family time, family support, time with friends, friend deviance, knowledge of friends, activities, and neighborhood problems. An associative latent growth modeling (LGM) analysis showed significant increases and relations between the four behaviors in both initial status and development. Second-order multivariate LGM analyses indicated that the four behaviors could be modeled by a higher-order problem behavior construct. Significant effects on the common problem behavior intercept or slope included time with friends, deviant friends, age, marital status, family time, and support. Additional effects were found to be specific to the initial status and slopes of individual problem behaviors. Overall, results indicate the importance of assessing the relations between adolescent problem behaviors as they change over time and identifying the risk and protective factors that have both common and individual influences on these behaviors.

Adolescent↗

PubMed2000

Physical activity, self-esteem, and self-efficacy relationships in older adults: a randomized controlled trial.

A randomized controlled trial examined the growth and form of multidimensional self-esteem over a 12-month period (6-month exercise intervention and 6-month follow-up) in 174 older adults engaged in either a walking or stretching/toning program. The extent to which changes in physical fitness parameters and physical self-efficacy were related to changes in perceptions of attractive body, strength, physical conditioning, and physical self-worth was also determined. Latent growth curve analyses showed a curvilinear pattern of growth in esteem with significant increases at all levels of self-esteem upon completion of the intervention followed by significant declines at 6 months postintervention in both groups. Frequency of activity and changes in physical fitness, body fat, and self-efficacy were related to improvements in esteem perceptions relative to attractive body, strength, and physical condition. Model fitting procedures suggested that the best fit of the data was to a model in which the influence of changes in efficacy and physical parameters on physical self-worth were mediated by perceptions of attractive body and physical condition.

Aged↗

PubMed2000

Development and evaluation of an interactive CD-ROM refusal skills program to prevent youth substance use: "refuse to use".

An interactive CD-ROM program designed to reduce adolescent substance use was developed and evaluated. The program uses video vignettes to teach refusal skills and socially acceptable responses to substance use situations, specifically offers of marijuana. In a randomized pretest-to-posttest experiment with 74 public school students from six classes in three high schools, significant changes were observed at posttest on (1) the adolescent's personal efficacy to refuse the offer of marijuana, (2) the adolescent's intention to refuse marijuana if offered, and (3) the adolescent's perceptions of the social norms associated with substance use and the importance of respecting another's decision to refuse a drug offer. In addition, adolescents in the treatment condition were able to recall approximately 50% of the portrayed refusal strategies. Findings are discussed with regard to the potential benefits of an interactive multimedia approach for conducting substance use interventions.

Adolescent↗

PubMed2000

Effects of the "Preparing for the Drug Free Years" curriculum on growth in alcohol use and risk for alcohol use in early adolescence.

Preparing for the Drug-Free Years (PDFY) is a curriculum designed to help parents learn skills to consistently communicate clear norms against adolescent substance use, effectively and proactively manage their families, reduce family conflict, and help their children learn skills to resist antisocial peer influences. This study examined the effects of PDFY on the trajectories of these factors, as well as on the trajectory of alcohol use from early to mid adolescence. The sample consisted of 424 rural families of sixth graders from schools randomly assigned to an intervention or a control condition. Data were collected from both parents and students at pretest, posttest, and 1-, 2- and 3 1/2-year follow-ups. Latent growth models were examined. PDFY significantly reduced the growth of alcohol use and improved parent norms regarding adolescent alcohol use over time. Implications for prevention and evaluation are discussed.

Adaptation, Psychological↗

PubMed1999

Adolescent problem behavior: the influence of parents and peers.

This paper presents evidence that the Patterson et al. (1992) model of development of antisocial behavior in children generalizes to the development of a wide array of problem behaviors during later adolescence and that youth antisocial behavior, high-risk sexual behavior, academic failure and substance use form a single problem behavior construct. Structural equation modeling methods were applied to 24-month longitudinal data from 204 adolescents and parents. The model fit the data well, accounting for 52% of the variance in adolescent problem behavior. Specifically, families experiencing high levels of conflict were more likely to have low levels of parent-child involvement. These family conditions were related to poor parental monitoring and association with deviant peers one year later. Poor parental monitoring and associations with deviant peers were strong proximal predictors of engagement in an array of problem behaviors at two-year follow-up.

Adolescent↗

PubMed1999

Exploring associations in developmental trends of adolescent substance use and risky sexual behavior in a high-risk population.

This study examined associations between the development of adolescent alcohol, cigarette, and marijuana use and risky sexual behavior, over time, using latent growth modeling methodology. Gender differences in the development and relationships between use of substances and risky sexual behavior were also examined. Participants were 257 adolescents (mean age = 15.96 years) assessed at three time points over an 18-month period. The intercepts of marijuana with cigarettes and alcohol, and all three substances with risky sexual behavior were significantly related. Development of the three substances showed similar patterns and development of cigarette use covaried with development of risky sexual behavior. There were no significant differences for boys and girls in these relationships. Results are discussed in relation to the need for greater understanding of nonsexual and sex-related problem behaviors and for analyses examining development and change in these behaviors during adolescence.

Adolescent↗

PubMed1999

Development of adolescent problem behavior.

The developmental model of adolescent antisocial behavior advanced by Patterson and colleagues (e.g., Patterson, Reid, & Dishion, 1992) appears to generalize the development of a diverse set of problem behaviors. Structural equation modeling methods were applied to 18-month longitudinal data from 523 adolescents. The problem behavior construct included substance use, antisocial behavior, academic failure, and risky sexual behavior. Families with high levels of conflict were less likely to have high levels of parent-child involvement. Such family conditions resulted in less adequate parental monitoring of adolescent behavior, making associations with deviant peers more likely. Poor parental monitoring and associations with deviant peers were strong predictors of engagement in problem behavior. These constructs accounted for 46% of the variance in problem behavior. Although association with deviant peers was the most proximal social influence on problem behavior, parental monitoring and family factors (conflict and involvement) were key parenting practices that influenced this developmental process.

Achievement↗

PubMed1999

Mode of physical activity and self-efficacy in older adults: a latent growth curve analysis.

A randomized controlled trial examined the effect of two physical activity modes on changes in self-efficacy over the course of a 12-month period in older, formerly sedentary adults (N = 174, M age = 65.5 years). Participants were randomized into either an aerobic activity group or a stretching and toning group. Structural equation modeling was employed to conduct multiple sample latent growth curve analyses of individual growth in exercise and physical self-efficacy over time. Results revealed a curvilinear growth pattern for both types of efficacy with increases occurring over the first 6 months followed by declines at the 6-month follow-up. There was a significant treatment by mean level growth interaction for exercise efficacy with both groups increasing over time, but the aerobic group evidenced a twofold increase in growth over the stretching group. Structural analyses indicated that frequency of exercise participation was a significant predictor of overall growth in efficacy, and improvements in fitness were only related to exercise efficacy growth in the stretching group. Findings are discussed in terms of social cognitive theory and further application of latent growth curve modeling to studies of physical activity effects in older adults.

Activities of Daily Living↗

PubMed1998

Contributions of the social context to the development of adolescent substance use: a multivariate latent growth modeling approach.

This article demonstrates a latent growth curve methodology for analyzing longitudinal data of adolescent substance use. Hypotheses concerning the form of growth in alcohol, cigarette, and marijuana use, and covariates influencing the form of growth, were tested. Participants were male and female adolescents (n = 664) assessed at three time points. A common trajectory existed across the developmental period with significant increases in all three substances. Second-order multivariate extensions of the basic latent growth modeling framework suggested that associations among the individual differences parameters, representing growth or change in the various substance use behaviors, could be adequately modeled by a higher-order substance use construct. Inept parental monitoring, parent-child conflict, peer deviance, academic failure, gender, and age, were significant predictors of initial levels and the trajectory of substance use.

Achievement↗

PubMed1998

Progressions of alcohol, cigarette, and marijuana use in adolescence.

This study examined the progressive relations among adolescent use of alcohol, cigarettes and marijuana using latent growth curve analyses. Specifically, the present study examined three models to determine (1) the effect of prior cigarette use on alcohol use and development and the relationship between change in cigarette use and the development of alcohol use (N = 115), (2) the effect of prior alcohol use on cigarette use and development and the relationship between change in alcohol use and the development of cigarette use (N = 199); and (3) the effect of prior alcohol and cigarette use on marijuana use and development, and the relationship between change in alcohol use and cigarette use and the development, of marijuana use (N = 287). Support was found for the relation between prior levels of substance use and involvement in other substances. Cigarette use, in particular, was particularly important in the subsequent involvement of alcohol and marijuana.

Adolescent↗

PubMed1998

Confirmatory factor analysis of the Task and Ego Orientation in Sport Questionnaire with cross-validation.

Although a number of factor analytic studies have been conducted on the factorial validity of the Task and Ego Orientation in Sport Questionnaire (TEOSQ), the results have been equivocal. To further substantiate its evidence of validity, this study cross-validated the measurement model using a rigorous structural equation modeling (SEM) approach. Data collected from a college student sample were first analyzed on a calibration sample (n = 439). Results confirmed the two-factor orthogonal structure representing the underlying task and ego orientations. The results were cross-validated on a validation sample (n = 439) using various SEM-based cross-validation procedures. Collectively, these findings support the construct validity of the TEOSQ as a measure of achievement goal orientation.

Achievement↗

PubMed1998

Latent variable modeling of longitudinal and multilevel alcohol use data.

OBJECTIVE: This article demonstrates use of a latent variable model for longitudinal data which encompasses nested structures. Using Multilevel Latent Growth Modeling (LGM), levels of alcohol use and development of alcohol use over 4 years were examined among individuals (adolescents and parents) nested within families. METHOD: An LGM model was tested for alcohol use with a sample of 435 families (435 target adolescents, 203 sibling and 566 parents [168 fathers and 398 mothers]). Adolescents (targets and siblings) comprised 312 boys and 326 girls, with a mean (+/-SD) age at Time 1 (T1) of 13.69 +/- 1.95 years. It was hypothesized that there would be homogeneity in level and development of alcohol use among family members and heterogeneity in alcohol use and development across families. The effects of family status (single-parent, two-parent intact and stepparent families) and socioeconomic status (SES) on family levels of alcohol use were also examined. RESULTS: Results suggested that stepparent families, and less educated and more economically disadvantaged families, had higher family levels of alcohol use and developed in their use of alcohol at a faster rate. CONCLUSIONS: Findings suggest that the alcohol use of individuals in the same family is more alike than that of individuals from different families and that family alcohol use may be influenced by family-level variables such as family status or SES. Methods such as those presented, which incorporate family-level clustering, are likely to provide additional information regarding the etiology of alcohol use and risk factors for alcohol use within and across families.

Adolescent↗

PubMed1997

Multi-level covariance structure analysis of intra-familial substance use.

Conventional covariance structure analysis, such as factor analysis, is often applied to data that are obtained in a hierarchical fashion, such as parents and siblings observed within families. However, multivariate modeling of such data are most frequently done as if the data were obtained as a simple random sample from a single population. An alternative specification is presented which explicitly models the within-level and between-level covariance matrices in familial substance use. Results demonstrate homogeneity in substance use within families but heterogeneity across families which could be accounted for by family-level variables of marital status, economic status, and biological relationships. It is shown that conventional covariance structure software can be easily adapted to handle hierarchical models, providing a large set of new analysis possibilities for multi-level data.

Adolescent↗

PubMed1997

Adolescent alcohol use development and young adult outcomes.

This study used latent growth modeling to examine the effects of level of alcohol use and development of alcohol use during adolescence, on young adult outcomes for males and females. Adolescents (N = 480; mean = 13.03 years, S.D. = 1.44; 264 female) were assessed annually over a 4-year period and then 5-6 years later in young adulthood (mean = 22.49 years, S.D. = 1.50). Chronicity of alcohol use in adolescence was related to higher alcohol use, alcohol-related problems, aggressive behavior, theft, and suicide ideation in young adulthood among both males and females. Development of alcohol use during adolescence was related to alcohol-related problems in young adulthood for males and females, and to higher levels of alcohol use and aggressive behavior for males only. The results indicate that development of alcohol use as well as level of alcohol use in adolescence is important for future adjustment outcomes, and that these relationships vary as a function of gender.

Adolescent↗

PubMed1996

Experimental evaluation of a modular approach to mobilizing antitobacco influences of peers and parents.

The experimental evaluation of two components of a community intervention to prevent adolescent tobacco use are described. Youth antitobacco activities (e.g., peer quizzes, sidewalk art, poster and T-shirt giveaways, etc.) and family communications activities (pamphlets to parents and student quizzes of parents) were evaluated in two time-series experiments, each of which was conducted in two experimental and one control community. Students in Grades 6 and 8 and their parents were assessed in a series of four phone surveys in the first experiment and six phone surveys in the second. Implementation of the youth antitobacco and family communications activities led to significantly greater exposure of young people to antitobacco information. They led to increases in parent and youth knowledge about tobacco use and more negative attitudes toward tobacco. In Experiment 2, youths in intervention communities had significantly lower rated intentions to smoke. The findings suggest the value of a modular approach to community interventions for influencing the social context relevant to the onset of adolescent tobacco use.

Adolescent↗