Publication Date




Embargo Period


Degree Type


Degree Name

Doctor of Philosophy (PHD)


Psychology (Arts and Sciences)

Date of Defense


First Committee Member

Annette M. La Greca

Second Committee Member

Elizabeth Pulgaron

Third Committee Member

Kristin M. Lindahl

Fourth Committee Member

Alan Delamater

Fifth Committee Member

Lisa Gwynn


Purpose/Objective: Behaviors shaped and defined in childhood and adolescence can have long-term implications for morbidity and mortality in adulthood. Effective interventions to increase positive health behaviors (e.g., healthy eating habits, physical activity, stress management), in adolescence are vital. Per the American Dietetic Association (ADA), effective interventions to promote positive health behaviors in adolescents should include nutrition education, regular physical activity, and behavioral counseling (ADA, 2006). Yet, interventions to promote positive health behaviors have been less effective in minority populations. Motivational interviewing (MI) has demonstrated effectiveness at promoting change behaviors in a variety of contexts (e.g., substance abuse, health behaviors, treatment engagement) and with adolescents (Lundahl, Kunz, Brownell, Tollefson, & Burke, 2010; Markland, Ryan, Tobin, & Rollnick, 2005). This study aimed to (1) evaluate the feasibility of administering a preventative health intervention to minority, low-SES middle school students by examining patterns of enrollment, dropout, and program attendance, (2) evaluate the acceptability of administering a preventive health intervention to minority, low-SES middle school students by examining participant ratings of program satisfaction, (3) evaluate the pre-to-post intervention benefit of the Expand, Connect, Thrive (ECT) program on eating behaviors, physical activity, and utilization of coping skills, (4) evaluate whether the ECT effects are maintained at the 3-, 6-, and 9-month follow-up, and (5) examine whether adding MI to the ECT program enhances ECT’s effects on the primary outcomes, both at post-intervention and at follow-up. As an exploratory aim (6), this study evaluated whether gender, intrinsic motivation, and anthropometric measurements moderate the effects of ECT and ECT-plus-MI interventions. Finally, due to limited findings from the pre- to post-intervention analyses, focus groups were conducted with adolescents to determine how the intervention could be adjusted to be more effective. Methods: Sixty-two adolescents (56% female, ages 10-14 years; 17% Hispanic, 56% Haitian/Creole) were approached to participate in the ECT study at the time of their enrollment in the ECT summer camp at a school-based health clinic, hosted at a middle school in south Florida that primarily serves low-income, minority adolescents. Inclusion criteria included (1) having completed 5th grade, (2) having not yet entered 9th grade, (3) being willing and able to give informed assent, (4) having a parent willing and able to give informed consent, (5) being able to speak and read English, and (6) being enrolled in the host school in Fall, 2017. Exclusion criteria included (1) previous diagnosis of intellectual disability. Fifty-one adolescents were eligible for study inclusion and forty-eight were enrolled. The ECT health intervention included nutrition education (1-hour sessions, twice per week), and training in physical fitness (1-hour per day) and in mental health and coping skills (1-hour session, once per week). Half of the sample was randomly assigned to additionally receive MI sessions. Adolescents were assessed (T1) prior to the ECT intervention, (T2) at the conclusion of the ECT intervention, (T3) 3 months post-ECT, and (T4) 6 months post-ECT. Assessments included self-report measures of eating behavior, physical activity, perceived stress, and coping strategies to evaluate the preliminary pre-to-post intervention benefit of the ECT program, both with and without the MI enhancement. Gender, intrinsic motivation, and anthropometric measurements were also collected to evaluate their function as moderators of change from pre-to-post intervention. A selection of eating behavior and physical activity questions that are included in the Youth Risk Behavior Surveillance were used to compare this sample to a national average. Additionally, to evaluate intervention acceptability, adolescents completed satisfaction surveys at the end of the intervention. Finally, data on enrollment, attendance, and dropouts were used to evaluate program feasibility. All key elements of the study design are consistent with TREND (See Appendix A). Results: The ECT program demonstrated an overall retention rate of 79%. Overall, adolescents who completed the program had high rates of attendance, with the average participant attending 82.58% of 29 days (range of 37.93-100%). Adolescents’ satisfaction ratings suggested that they were satisfied with the camp program; 75% rated the quality of the program as “Excellent” or “Good” and about 73% indicated that they would likely recommend the ECT program to a friend in need of a similar program. Change in primary outcomes was shown to be significant, F(6, 41) = 2.951, p = .017, partial η2 = .302). However, this effect was primarily driven by the Physical Activity Questionnaire: Sedentary scale, in which there was a significant decrease from baseline (T1) to post-intervention (T2), suggesting that youth became less sedentary over time. No other primary analyses were significant at post-intervention or at 6-month follow-up. Some specific differences were seen by gender, intrinsic motivation, weight status, and blood pressure. However, these effects were primarily main effects, rather than interaction effects. Thus, while support was found for hypothesized differences between those with higher vs lower risk for poor health behaviors, these differences did not influence the impact of the intervention. Focus groups, which were conducted because the intervention effects were shown to be minimal, indicated that adolescents wanted a higher degree of control and input in the intervention, and would have preferred the intervention to be more tailored to their individual needs. Additionally, adolescents offered recommendations to adjust the duration, frequency, and format of the intervention, while noting that the content was helpful and sufficient. Conclusions: Effects were largely in the area of physical activity, which adolescents noted was possibly due to the structured nature of the intervention. Effects of the intervention were minimal and not maintained over time, which adolescents suggested were due to the lack of sufficient context given to intervention content, the lack of parental engagement in the intervention, and the lack of continued structure and support for physical activities during the school year. While the intervention demonstrated little effect, this study laid the foundation for an adapted version of the ECT intervention using the adolescents’ suggestions. Future research should test the adapted ECT intervention.


healthy behaviors, adolescents, intervention, minority, prevention

Available for download on Wednesday, June 30, 2021