Biomedical subjects

D P MacKinnon

Publications and source records attributed to D P MacKinnon.

At least 19 recordsLinked to original sources

PubMed2001

Mediating mechanisms in a program to reduce intentions to use anabolic steroids and improve exercise self-efficacy and dietary behavior.

This study investigated the mediating mechanisms responsible for the effects of a program designed to reduce intentions to use anabolic steroids, improve nutrition, and increase strength training self-efficacy. Fifteen of 31 high school football teams (N = 1,506 players at baseline) in Oregon and Washington were assigned to receive the intervention. The multicomponent program addressed the social influences promoting ergogenic drug use and engaging students in healthy nutrition and strength training alternative behaviors. Although the results differed across the three dependent variables, the program appeared to work by changing team norms. Unlike prevention of other drugs, changes in knowledge and perceived severity were mediators of program effects in this study.

Adolescent↗

PubMed2001

Longitudinal relationship between the alcohol warning label and alcohol consumption.

OBJECTIVE: The present study reports the longitudinal relationship between alcohol warning label exposure and alcohol consumption among adolescents. METHOD: In-school surveys assessed adolescents at three annual time points beginning in tenth grade. There were 649 participants measured at all three time points; 51% were female. Four effects were the focus of the covariance structure, latent growth analysis of these data: (1) an exposure effect, whereby earlier alcohol use leads to more exposure to the warning label; (2) a deterrent effect, whereby earlier alcohol warning label exposure reduces subsequent alcohol consumption; (3) a harmful effect, corresponding to a positive relationship between early exposure and subsequent consumption; and (4) both exposure and deterrent effects operating at the same time. RESULTS: There was a statistically significant exposure effect such that earlier alcohol use was associated with later exposure to the warning. The association between earlier alcohol warning label exposure and subsequent alcohol use was generally negative but not statistically significant, suggesting that the warning did not affect alcohol consumption. CONCLUSIONS: These results suggest that the alcohol warning label is having the intended effect as described in the law requiring the warning. That is, it is informing and reminding persons of the risks associated with alcohol use. The warning does not appear to significantly increase or decrease alcohol consumption.

Adolescent↗

PubMed2000

The adolescents training and learning to avoid steroids program: preventing drug use and promoting health behaviors.

BACKGROUND: Use of alcohol and other illicit drugs by adolescent male athletes is a significant problem. Participation in sports may encourage use of drugs that enhance athletic performance, especially anabolic steroids (AS). Because, to our knowledge, no other intervention has successfully altered substance abuse by athletes, we developed and assessed the efficacy of a team-centered, sex-specific education program designed to reduce adolescent athletes' intentions to use and use of AS and alcohol and other illicit drugs. METHODS: We studied 31 high school football teams that comprised 3207 athletes in 3 successive annual cohorts (1994-1996). The intervention included interactive classroom and exercise training sessions given by peer educators and facilitated by coaches and strength trainers. Program content included discussion of sports nutrition, exercise alternatives to AS and sport supplements, and the effects of substance abuse in sports, drug refusal role-playing, and the creation of health promotion messages. Questionnaires assessing AS, the use of sport supplements and alcohol and other illicit drugs, and potential risk and protective factors were administered before and after the intervention (before and after the football season) and up to 1 year after the program. RESULTS: At season's end, intentions to use (P<.05) and actual AS use (P<.04) were significantly lower among students who participated in the study. Although AS reduction did not achieve significance at 1 year (P<.08), intentions to use AS remained lower (P = .02). Illicit drug use (marijuana, amphetamines, and narcotics) was reduced at 1 year, whether alcohol was included (P = .04) or excluded (P = .02) from the index. Other long-term effects included fewer students reporting drinking and driving (P = .004), less sport supplement use (P = .009), and improved nutrition behaviors (P<.02). CONCLUSIONS: Use of alcohol and other illicit drugs and associated harmful activities can be prevented with a sex-specific, team-centered education. School athletic teams provide an optimal environment in which to provide drug prevention and health promotion education.

Adolescent↗

PubMed2000

Equivalence of the mediation, confounding and suppression effect.

This paper describes the statistical similarities among mediation, confounding, and suppression. Each is quantified by measuring the change in the relationship between an independent and a dependent variable after adding a third variable to the analysis. Mediation and confounding are identical statistically and can be distinguished only on conceptual grounds. Methods to determine the confidence intervals for confounding and suppression effects are proposed based on methods developed for mediated effects. Although the statistical estimation of effects and standard errors is the same, there are important conceptual differences among the three types of effects.

Bias↗

PubMed2000

Home smoking restrictions and adolescent smoking.

The prevention of adolescent smoking has focused on peer influences to the relative neglect of parental influences. Parents socialize their children about many behaviors including smoking, and parental rules about their child's smoking have been related to lower levels of adolescent smoking. Moreover, among adults, indoor smoking restrictions have been associated with decreased smoking. Accordingly, the current study tested the relation of adolescent smoking to home smoking policy (rules regulating where adults are allowed to smoke in the home). Results showed that restrictive home smoking policies were associated with lower likelihood of trying smoking for both middle and high school students. However, for high school students this relation was restricted to homes with non-smoking parents. Home smoking policies were not associated with current regular smoking for either middle or high school students. Home smoking policies may be useful in preventing adolescent smoking experimentation, although longitudinal and experimental research is necessary to confirm this hypothesis.

Adolescent↗

PubMed2000

The alcohol warning and adolescents: 5-year effects.

OBJECTIVES: This study, a follow-up to the authors earlier report, examined the effects of the alcohol warning label on adolescents during the first 5 years that the warning was required. METHODS: Surveys were administered to 10th-grade (n = 16,661) and 12th-grade (n = 15,856) students from the 1989-1990 school year through the 1994-1995 school year. The measures were awareness of, exposure to, and recognition memory of the alcohol warning label; beliefs about the risks listed on the warning; and open-ended statements about consequences of alcohol use, alcohol consumption, and self-reported driving after drinking. RESULTS: There were increases in warning awareness, exposure, and recognition memory. These effects leveled off approximately 3.5 years after the inclusion of the warning on alcohol beverage containers. There was no beneficial change attributable to the warning in beliefs, alcohol consumption, or driving after drinking. CONCLUSIONS: The initial positive effects of the alcohol warning label on adolescents have leveled off, consistent with theories of repeated exposure to persuasive information. The alcohol warning has not affected adolescents' beliefs about alcohol or alcohol-related behaviors.

Adolescent↗

PubMed1999

Multilevel mediation modeling in group-based intervention studies.

This article proposes and evaluates a method to test for mediation in multilevel data sets formed when an intervention administered to intact groups is designed to produce change in individual mediator and outcome variables. Simulated data of this form were used to compare ordinary least squares (OLS) and two multilevel estimators of the mediated effect. OLS and multilevel standard error approximations were also evaluated and recommendations given for optimal estimator choice. These methods were applied to data from an existing substance use intervention to show the impact multilevel mediation modeling can have on the conclusions drawn from real-world evaluation studies.

Analysis of Variance↗

PubMed1998

Designated driving among college students.

OBJECTIVE: We studied the frequency of designated driver use, predictors of designated driver use, whether designated drivers use alcohol, and barriers to using a designated driver. METHOD: Undergraduates at Arizona State University (N = 544) completed a questionnaire assessing designated driver use. The mean age of participants was 20.6 years old and 52% were male. Criterion for inclusion in the study was that participants had consumed alcohol at least one time. RESULTS: Eighty-six percent (86%) of participants had used a designated driver. Monthly alcohol use and driving to drinking destinations were positively associated with designated driver use. Ninety-four percent of participants indicated that their designated driver occasionally consumed alcohol. The most frequent reason for not using a designated driver was, "I stayed where I was drinking until I was sober" (37%). Less alcohol use among friends was associated with sounder methods of designated driver selection. CONCLUSIONS: Findings suggest those groups at risk for alcohol-related driving accidents tend to use designated drivers at high rates, but these groups tend to choose designated drivers who consume alcohol.

Accidents, Traffic↗

PubMed1998

Effects of a community-based prevention program on decreasing drug use in high-risk adolescents.

OBJECTIVES: This study investigated the secondary prevention effects of a substance abuse primary prevention program. METHODS: Logistic regression analyses were conducted on 4 waves of follow-up data from sixth- and seventh-grade baseline users of cigarettes, alcohol, and marijuana taking part in a school-based program in Indianapolis. RESULTS: The program demonstrated significant reductions in cigarette use at the initial follow-up (6 months) and alcohol use at the first 2 follow-ups (up to 1.5 years). Models considering repeated measures also showed effects on all 3 substances. CONCLUSIONS: Primary prevention programs are able to reach and influence high-risk adolescents in a nonstigmatizing manner.

Adolescent↗

PubMed1997

Concepts of drugs: differences in conceptual structure across groups with different levels of drug experience.

Seventy-seven college students varying in degree of drug use experience rated the perceived similarities of all possible combinations of 16 drugs classes (cigarettes, other tobacco, alcohol, marijuana, barbiturates, minor and major tranquilizers, amphetamines, amphetamine derivatives, cocaine, heroin, opiates, hallucinogens, inhalants, PCP, anti-depressants). Multi-dimensional scaling (INDSCAL) and network models (PFNET) indicated that abstainers had only one pharmacological category involving sedatives/depressants, and that they attached more importance to whether drugs were licit vs. illicit than to whether they were depressants vs. stimulants. Conceptions became more coherent, differentiated and based on pharmacological properties for more experienced drug users. In line with previous work, groups with greater experience with drugs had more sophisticated conceptions not only about the drugs they had used, but also about drugs they had not used. These findings suggest that early on in drug behavior sophisticated and interrelated concepts are developing that should be taken into account when designing interventions and information campaigns.

Adult↗

PubMed1996

Effects of a multidimensional anabolic steroid prevention intervention. The Adolescents Training and Learning to Avoid Steroids (ATLAS) Program.

OBJECTIVE: To test a team-based, educational intervention designed to reduce adolescent athletes' intent to use anabolic androgenic steroids (AAS). DESIGN: Randomized prospective trial. SETTING: Thirty-one high school football teams in the Portland, Ore, area. PARTICIPANTS: Seven hundred two adolescent football players at experimental schools; 804 players at control schools. INTERVENTION: Seven weekly, 50-minute class sessions were delivered by coaches and student team leaders, addressing AAS effects, sports nutrition and strength-training alternatives to AAS use, drug refusal role play, and anti-AAS media messages. Seven weight-room sessions were taught by research staff. Parents received written information and were invited to a discussion session. MAIN OUTCOME MEASURES: Questionnaires before and after intervention and at 9- or 12-month follow-up, assessing AAS use risk factors, knowledge and attitudes concerning AAS, sports nutrition and exercise knowledge and behaviors, and intentions to use AAS. RESULTS: Compared with controls, experimental subjects at the long-term follow-up had increased understanding of AAS effects, greater belief in personal vulnerability to the adverse consequences of AAS, improved drug refusal skills, less belief in AAS-promoting media messages, increased belief in the team as an information source, improved perception of athletic abilities and strength-training self-efficacy, improved nutrition and exercise behaviors, and reduced intentions to use AAS. Many other beneficial program effects remained significant at the long-term follow-up. CONCLUSIONS: This AAS prevention program enhanced healthy behaviors, reduced factors that encourage AAS use, and lowered intent to use AAS. These changes were sustained over the period of 1 year. Team-based interventions appear to be an effective approach to improve adolescent behaviors and reduce drug use risk factors.

Adolescent↗

PubMed1996

The Adolescents Training and Learning to Avoid Steroids (ATLAS) prevention program. Background and results of a model intervention.

OBJECTIVE: To develop and test a school-based intervention to prevent anabolic androgenic steroid use among high-risk adolescent athletes. DESIGN: Nonrandom controlled trial. SETTING: Two urban high schools. PARTICIPANTS: Fifty-six adolescent football players at the experimental school and 24 players at the control school. INTERVENTION: Eight weekly, 1-hour classroom sessions delivered by the coach and adolescent team leaders, and eight weight-room sessions delivered by research staff. The intervention addressed sports nutrition and strength training as alternatives to steroid use, drug refusal role play, and antisteroid media campaigns. OUTCOME MEASURES: A preintervention and postintervention questionnaire that assessed attitudes toward and intent to use steroids and other drugs; knowledge of drug effects; and diet, exercise, and related constructs. RESULTS: Compared with controls, experimental subjects were significantly less interested in trying steroids after the intervention, were less likely to want to use them even if their friends used them, were less likely to believe steroid use was a good idea, believed steroids were more dangerous, had better knowledge of alternatives to steroid use, had improved body image, increased their knowledge of diet supplements, and had less belief in these supplements as beneficial. CONCLUSIONS: Significant beneficial effects were found despite the sample size, suggesting that the effects of the intervention was large. This outcome trial demonstrates an effective anabolic androgenic steroid prevention program for adolescent athletes, and the potential of team-based interventions to enhance adolescents' health.

Adolescent↗

PubMed1996

Injuries and use of protective equipment among college in-line skaters.

In-line skating injuries and protective gear use were explored in a sample of college students (n = 217). A minority of respondents wore protective gear. One third of skaters had experienced at least one minor injury, and a smaller percentage had experienced fractures or head injuries. Most minor injuries occurred during the first 1-2 times skating, while more serious injuries tended to occur after at least 50 times on in-line skates. Psychosocial predictors of protective gear use were explored. Four major Health Belief Model constructs (perceived barriers to wearing gear, perceived susceptibility to injury, perceived severity of injury, and perceived benefits of wearing gear) were significant predictors of protective gear use. The Health Belief Model, tested using regression and structural equation modelling, predicted gear typically worn, frequency of gear use, and injuries received while in-line skating. Implications for increasing protective gear use are described.

Adolescent↗

PubMed1995

The risk of assaultive violence and alcohol availability in Los Angeles County.

OBJECTIVES: Although there is considerable evidence that alcohol consumption facilitates assaultive violence, the extent to which alcohol outlets in a community influence assaultive violence remains controversial. METHODS: To assess the geographic association between city-specific rates of assaultive violence and alcohol-outlet density, an ecologic analysis of the 74 larger cities in Los Angeles County was conducted for the 1990 reporting year. RESULTS: Sociodemographic factors alone accounted for 70% (R2 = .70) of the variance in the rate of assaultive violence in a multiple regression model. Adding the variable for alcohol-outlet density to the model yielded a significant positive slope. The magnitude of this relation indicates that in a typical Los Angeles County city (50,000 residents, 100 outlets, 570 offenses per year), one outlet was associated with 3.4 additional assaultive violence offenses in 1990. CONCLUSIONS: These findings indicate that higher levels of alcohol-outlet density are geographically associated with higher rates of assaultive violence. This association is independent of measured confounders, including city-level measures of unemployment, ethnic/racial makeup, income, age structure, city size, household size, and female-headed households.

Adult↗

PubMed1994

Alcohol outlet density and motor vehicle crashes in Los Angeles County cities.

The extent to which the availability of alcohol encourages alcohol consumption resulting in alcohol-related problems remains controversial. In order to address this issue we used 1990 data from 72 cities within Los Angeles County to estimate the relation between densities of four types of alcohol outlets (restaurants, bars, liquor stores, mini-markets) and rates of two types of alcohol-related motor vehicle crashes reported by police (injury, property damage). After logarithmic transformation of variables, crash rates were regressed on outlet densities and possible demographic confounders. The demographic covariates accounted for 25% of the variance in injury crashes; adding the combined outlet density to the model yielded a significant elasticity estimate (beta +/- SE) (beta = 0.55 +/- 0.13). Separate models for types of outlets yielded significant elasticities for restaurants (beta = 0.22 +/- 0.07), liquor stores (beta = 0.46 +/- 0.17) and mini-markets (beta = 0.34 +/- 0.13), but not for bars (beta = 0.08 +/- 0.07). Alcohol-related crashes resulting in property damage also showed positive associations with outlet densities, but these associations were smaller and reached statistical significance for restaurants (beta = 0.19 +/- 0.11) and bars (beta = 0.21 +/- 0.10). Direction of influence cannot be inferred from these cross-sectional findings, but they do indicate that increased alcohol availability is geographically associated with increased alcohol-related motor vehicle crashes and that this association is independent of measured confounders.

Accidents, Traffic↗

PubMed1994

Analysis of mediating variables in prevention and intervention research.

Mediational analysis is one way to test specific hypotheses derived from theory. Although this analysis has been suggested in the prevention literature, mediation analysis rarely is conducted. As the field of prevention matures, more questions about how prevention programs work (or fail to work) will emerge. Studies of mediation can address these questions, thereby reducing the cost and enhancing the impact of prevention programs. The methods outlined here can be applied in the evaluation of primary, secondary, and tertiary prevention programs. Since most prevention studies include measurement of some mediating constructs, mediation effects can be assessed on many existing data sets. Mediation analysis can be used to test ideas about prevention.

Data Interpretation, Statistical↗

PubMed1993

Substance use and memory for health warning labels.

This article reports the relationship between substance use and memory for health warnings for cigarettes, smokeless tobacco, and alcohol. Measures of substance use and recognition memory for warning labels were collected from 2 samples of college students (n = 288 and n = 243). It was hypothesized that if health warnings were noticed and remembered, then users, because they were often exposed to the warning labels, would have more accurate memory for the risks written on the containers of these products than nonusers. Prior research had not confirmed this relationship. In Study 1, a statistically significant correlation was obtained between use and recognition memory for both cigarettes and smokeless tobacco. The effects for cigarettes and smokeless tobacco were replicated in Study 2 and observed for alcohol as well.

Adult↗

PubMed1993

Generality and specificity in health behavior: application to warning-label and social influence expectancies.

The authors outlined a meta-theoretical and an analytic framework for construing the predictive effects of health-behavior expectancies, or beliefs, in terms of both general and specific processes. This framework was applied empirically to the investigation of the predictive effects of outcome expectancies related to the recently mandated alcohol-warning label as well as to expectancies reflecting social influence processes. Results showed that general and specific predictive effects of expectancies on alcohol-use behaviors operated simultaneously, demonstrating the potential value of the framework. The authors summarized implications for continued theoretical development as well as for applications in prevention of alcohol abuse through warning-label and social influence interventions.

Adolescent↗