Participants
Clinically anxious youth were recruited from a larger study (n = 34) assessing the utility of including a smartphone app in brief CBT, which consisted of 8 sessions [39]. Primary analyses focused on 18 participants who completed a mid-treatment exposure assessment. These 18 anxious youth were ages 9 to 14 (M = 11.38, SD = 1.66) who met DSM-5 [4] criteria for current Generalized Anxiety Disorder (n = 10), Separation Anxiety Disorder (n = 5), and/or Social Anxiety Disorder (n = 3). Of the 18 participants (50% female), 14 (77%) were European American, 3 (17%) were Biracial, and 1 (6%) was African American. Demographics are displayed in Table 1. Participants were recruited from a metropolitan city in the United States through (1) referrals from local pediatricians; (2) letters sent through a University-sponsored research registry to families interested in participating in behavioral health research studies; and (3) community advertising via flyers, internet, and print publications. Exclusion criteria included (1) neuromuscular or neurological disorder, (2) current comorbid psychiatric diagnosis that would require alternative treatment or interfere with treatment [i.e. major depressive disorder, obsessive-compulsive disorder, post-traumatic stress disorder, conduct disorder, substance abuse or dependence, or ADHD combined type or predominantly hyperactive-impulsive type], (2) a lifetime diagnosis of autism spectrum disorder, bipolar disorder, or psychotic disorder, (3) a prior trial of ≥6 sessions of CBT, (4) IQ below 70 as assessed by the Wechsler Abbreviated Scale of Intelligence (WASI: [45]) or reading level below 80 on the Wide Range Achievement Test-4 (WRAT-4: [46], 5) concurrent psychological therapy or treatment with anxiolytic or antidepressant medication (though could be on medication for ADHD if dose had been stable for at least 4 weeks), and (6) acute suicidality or risk for harm to self or others. A total of 34 youth met study criteria and completed brief CBT. The current study primarily focuses on the 18 youth who completed an additional assessment during a mid-treatment exposure (see Fig. 1). For further detail on eligibility requirements please [39].
Measures
Structured interviews for diagnosis and anxiety severity
Interviews were administered by trained post-doctoral fellows and clinical psychology doctoral students. Participants and their primary caregiver were individually administered the Kiddie – Schedule for Affective Disorders and Schizophrenia – Present and Lifetime Version (K-SADS-PL [26];) to determine past and current DSM-IV diagnostic status. Inter-rater reliability of anxiety diagnoses was satisfactory, κ = .77 (based on 15% of all assessments). The Pediatric Anxiety Rating Scale (PARS) was completed with the parent and child together to determine youth anxiety severity. The PARS is a clinician-rated interview that was developed to assess changes in pediatric anxiety in treatment studies, and its assessment of symptoms and severity accounts for the high co-morbidity of anxiety disorders in childhood [21]. The PARS exhibits excellent psychometric properties [36]. Anxiety severity was calculated by summing the six items assessing anxiety severity, frequency, distress, avoidance, and interference during the prior week (ICC = .91). We examined youth’s response to CBT in the current study by testing reduction in anxiety severity from pre-treatment to post-treatment and from pre-treatment to 2-month follow-up, respectively.
Psychophysiological assessment of emotional arousal
EDA data were collected using MindWare BioNex 3.13. Two disposable Ag/AgCl electrodes were placed on the palmar surface of the non-dominant hand. Data were sampled at 500 Hz and processed with the rolling filter. Tonic skin conductance level (SCL), which captures general changes in sympathetic arousal over time, was quantified by calculating the amount of microsiemens (or μS) occurring in 10 s segments. Data were visually inspected to ensure phasic components were detected. Because tonic-SCL did not tend to decrease or increase over time, average tonic-SCL across the exposure was computed. A log transformation was applied to normalize the data [12]. Twenty youth completed the EDA assessment. Two participants’ data were dropped due to poor data quality.
Subjective assessments of emotional arousal
Participants were instructed by their therapist to indicate their SUDS rating on a scale from 0 (minimum anxiety) to 8 (maximum anxiety). SUDS ratings were collected at approximately one-minute intervals starting with a baseline rating immediately prior to the start of the exposure and ending with the exposure completion. Fear activation was computed as the peak SUDS rating during the exposure (Peak-SUDS). Within-session habituation was calculated by subtracting final SUDS from Peak-SUDS, with higher scores indicating greater habituation (Habituation-SUDS).
The Responses to Stress Questionnaire (RSQ), measures voluntary and involuntary responses to stress in daily life (B. E [13].). We focus on the RSQ administered at session 4 as an index of trait physiological stress response closest in time to the exposure assessment (occurring sessions 5–7). The subscale assesses youth perception of bodily arousal during stressful events. Items from the subscale included “When I had problems, I felt it in my body (check all that apply): my heart raced, I felt hot or sweaty, my breathing sped up, my muscles got tight, none of these.” Internal consistency of this subscale in the present study was poor (α = 0.52 in the overall sample of 34 youth). Low consistency in this measure indicates youth varied in their report of perceiving different physical sensations when distressed. Although not ideal, lower internal consistency aligns with prior research supporting inconsistency in youth self-report, thus the RSQ was retained in the current study for supplemental analyses.
Procedure
All laboratory visits (including therapy and assessments) took place in rooms designed for conducting therapy (comfortable furniture and lighting). At the outset of the baseline assessment, parental consent and child assent were first obtained. During the baseline, post-treatment, and two-month follow-up assessments, participants were administered semi-structured interviews (K-SADS, PARS, RSQ) and self-report measures. After the baseline assessment, participants completed eight (weekly) sessions of Brief Coping Cat [17]. The first three sessions consisted of psychoeducation and cognitive restructuring. The final five sessions (4–8) consisted of progressive exposures [9]. At the start of the fourth session, youth completed surveys (including RSQ) to assess anxiety prior to starting exposures in therapy.
Prior to the fifth session, participants were informed about an optional study component in which EDA would be acquired during an exposure. The collection of EDA data during mid-treatment was intentional, as initial exposures are not ideal for multiple reasons. The clinician may under-estimate the client’s ability (i.e., make the exposure too easy). Conversely, an initial exposure may be more challenging than envisioned, and simultaneously introducing additional stimuli and new people (i.e., EDA equipment and research assistant collecting data) may distract the client or amplify anxiety unnecessarily. Either scenario could limit the validity of data collected or interfere with exposure effectiveness. Participants who consented had EDA data acquired for one exposure during session 5 (n = 7), 6 (n = 10), or 7 (n = 1) based on laboratory availability. Exposure length varied (M = 6.26 min, SD = 2.52). Clinicians encouraged youth to engage with the feared stimulus until SUDS were equal to or lower than baseline. Youth voluntarily completed the exposure assessment without compensation. The post-treatment assessment was conducted approximately two weeks after youth completed their final therapy session. The follow-up assessment was conducted approximately two months later.
Families were compensated for their participation in baseline and post-treatment assessments (up to $360 total). Therapy was provided free of charge. Youth voluntarily completed the exposure assessment without compensation. All study aspects were approved by the Institution Review Board of the University of Pittsburgh, and the current study adheres to CONSORT guidelines.
Data analytic plan
Multiple linear regressions tested whether Tonic-SCL, Peak-SUDS, and Habituation-SUDS predicted reductions in youth’s anxiety severity at post-treatment and at the 2-month follow-up, covarying for anxiety severity at the baseline assessment. The small sample size was underpowered to capture small and moderate effects. Therefore, in addition to reporting statistical significance we also we interpret effect sizes based on Cohen’s recommendations (r > .10, .30, .50 = small, moderate, and large respectively).