Effect of an ACT-based Intervention to Reduce Anxiety in Medical Students

Here we detail the methodology employed:

PARTICIPANTS AND METHODS Ethics The study was performed according to the Declaration of Helsinki. The protocol was approved by the Research and Ethics Committees of CUCS of the University of Guadalajara with the approval number CI-03023. All participants signed an informed consent form prior to enrollment. The interventions were delivered by health professionals trained in ACT.

Participants Adult medical students at the Health Sciences University Center of the University of Guadalajara who were studying from first to third semesters were invited to participate. The exclusion criteria were a) students that were participating in other psychological of intervention program, and b) students that did not complete all the sessions of the intervention.

Study period: The study was performed in two time points, one in 2023 and the second in 2025, in these two time points the intervention was performed to different participants by different instructors, finally the analyses were conducted with the combined sample.

Measurements Variables: The following variables were measured: psychological flexibility, assessed through four instruments corresponding to ACT-specific processes: the Acceptance and Action Questionnaire-II (AAQ-II) (Espinosa et al., 2010), range 1 - 7, measuring experiential avoidance; the Cognitive Fusion Questionnaire (CFQ) (Ruiz et al., 2017), range 1 - 7, measuring cognitive fusion; the Mindful Attention Awareness Scale (MAAS) (López-Maya, 2015), range 1 - 6, measuring mindfulness, and the Valuing Questionnaire (VQ), (Ruiz et al., 2021), range 0 - 6, measuring consistency with personal values. Negative psychological variables included anxiety, measured with the Generalized Anxiety Disorder scale (GAD-7), range 0 - 3, (Spitzer \& Kroenke, 2006; García-Campallo et al., 2010), depression, measured with the Patient Health Questionnaire-9 (PHQ-9), (Kroenke et al., 2001; Baader et al., 2012), range 0 - 3, somatization, measured with the Patient Health Questionnaire-15 (PHQ-15) (Ros-Montalbán et al., 2010), range 0 - 2, and stress, measured with the Perceived Stress Scale (PSS-14) (Cohen et al., 2010; Remor et al., 2006), range 0 - 4. Sleep satisfaction was assessed with the first item of the Oviedo Sleep Questionnaire (Bobes-García et al., 2000), range 1 to 7.

Sociodemographic and personal variables including age, sex, semester, relationship status (yes, no), socioeconomic level, measured as low, medium and high, alcohol and smoking consumption frequency (from never to 4 or more times in the week), daily minutes of physical activity, daily hours of free time, employment status (yes, no), history of psychological treatment (yes, no), and the number of self-reported health condition (21 different conditions including anxiety, depression, skin diseases, overweight, migraine, colitis, gastritis, allergies, gastrointestinal or respiratory infections, sinusitis, thyroid problems, hypertension, anorexia/bulimia, high cholesterol, renal problems, diabetes, rheumatic conditions, cardiac diseases, cerebral stroke and cancer). The presence of suicide ideation and suicide behavior were measured with the questions: "have you had thoughts of taking your own life?" and "have you taken any actions to try to take your own life?", respectively (answer options, yes, no). All these variables were collected via a Google Forms questionnaire.

Study 1. Design: Study one consisted in a cross-sectional design aimed in determining the correlation among the ACT-related variables with anxiety, depression and stress.

Participants: The participants were those who complied the selection criteria previously described.

Variables: The variables previously described and measured in the pre-test of the intervention program were included for this analysis.

Study 2. Design: This is a cuasi-experimental design with a pre-test and post-test measurements and a control group (psychoeducational session).

Participants: The students were directly invited in their classrooms to either of the 2 interventions in order to facilitate their participation in one schedule, those who accepted to participate were summoned at the University facilities in a schedule convenient for them and the instructor, to receive either the intervention program or the psychoeducational session on mental health.

Procedures: The experimental group received four weekly in-person group sessions based on ACT, conducted at the university facilities. The sessions addressed the six core processes of ACT (acceptance, cognitive defusion, being present, self as context, values, and committed action), with the therapeutic content oriented toward anxiety management. Session duration was 90 to 120 minutes. The sessions program is described in Table 1. The control group received a single psychoeducational session on mental health (90 minutes duration), which included a brief explanation of some techniques for anxiety regulation.

Variables: The previously mentioned variables were measured one week before intervention and 1 week after the final session. Measurements in the control group were conducted at the same time points as those in the intervention group. All measurements were performed via a google form questionnaire.

Table 1. Session program implemented in the intervention group Session number Objective General procedure

1. - Acceptance To facilitate the development of acceptance regarding unpleasant internal experiences (thoughts, emotions and physical sensations related with anxiety) a) Welcome b) Brief explanation of the specific process of ACT. c) Mindfulness exercise d) Exercise with metaphors related with the specific ACT process. e) Reinforce the process in daily life and give the participants related exercises as homework.
2. - Defusion and contact with the present moment. To reduce the impact of thoughts in anxiety or psychological distress by developing skills for cognitive defusion, by observing thoughts without becoming entangled in them, and conscious contact with the present moment.
3. - Me as a context and living values To foster a flexible perspective of the self (self as a context) and clarify personal values as compass for behavior, regardless of the presence of difficult internal experiences.
4. - Committed action Promote the execution of behaviors aligned with personal values, even in the presence of anxiety or psychological distress, thereby consolidating what was learned in previous sessions.

ACT: Acceptance and commitment therapy. Statistical analysis Descriptive statistics were obtained with means and standard deviations for quantitative variables with parametric distributions and with median and interquartile range for quantitative variables with non-parametric distributions. For qualitative variables frequencies and percentages were obtained. To perform the description of negative psychological variables including anxiety, depression, stress and somatization we obtained 4 to 5 categories (from low to severe) by dividing the possible range of each variable in the number of categories, the categories were determined according to the original instrument recommendations. To evaluate the instrument reliability of all psychological variables, the Cronbach alpha test was performed.

Study 1: Associations between ACT-specific variables, sociodemographic variables, and negative psychological variables were analyzed using Pearson's and Spearman's correlation tests depending on the data distribution. To determine the variables most associated with anxiety we performed a multivariate regression analysis using the stepwise method and including all the studied variables (dichotomous, quantitative and ordinals) as independent variable and excluding suicide ideation, suicide behavior and the negative psychological variables (depression, stress and somatization), this last by considering that these variables would not add information as effective predictors and possible objectives to reduce anxiety.

Study 2: To compare quantitative variables between groups at baseline, the student's t-test or Mann-Whitney U test was applied for parametric and non-parametric distributions, respectively, and the chi-squared test or Fisher's exact test was used for qualitative variables. To evaluate the effect of the intervention, the difference in each variable (posttest minus pretest) was compared between the experimental and control groups using the student's t-test or Mann-Whitney U test. Effect sizes were calculated using Cohen's D test. All analyses were conducted with SPSS software 31 and JASP program (JASP version 0.95.2) (JASP, 2025).