The persistent unmet need for youth mental health services, combined with the ubiquity of internet-equipped devices, has fueled a surge of interest in digital mental health interventions. Despite decades of progress in the identification of evidence-supported psychosocial treatments, myriad barriers—both systemic (high costs, transportation challenges) and internal (stigma, preferences for self-help)—prevent up to 80% of youth from accessing needed care [1,2]. The notion of low-cost, self-guided digital interventions thus appeals to researchers, providers, and clients alike. Indeed, mental healthcare apps are downloaded by millions of users annually [3,4], and a vast majority of adolescents in the United States have access to internet-equipped smartphones (95%) and computers (88%) [5]. These realities create opportunities for youth with no accessible alternatives to engage with digital supports.

Randomized trials suggest the promise of internet- and smartphone-based youth mental health tools [6-10]. However, formal clinical trial outcomes may not reflect the utility or usability of digital supports in naturalistic contexts. First, few evidence-based digital interventions developed for clinical trials are publicly accessible [11], and those that are accessible attract far fewer users than commercially popular but untested alternatives (eg, Headspace) [12]. Indeed, the most frequently downloaded mental health apps include few to no treatment elements found in empirically supported psychotherapies [13,14]. Second, digital intervention attrition rates differ markedly in clinical trials and “real-world” contexts. In a review of digital self-help tools, including apps and internet-based programs for depression and anxiety, completion rates for programs in clinical trials were 44%-99%. In contrast, completion rates for the same programs in naturalistic, non-research settings—where participants received no incentives for program engagement—were 1%-28% [15].

Overall, daily usage rates for mental health apps hovers at just 4% (based on rates of opening a previously downloaded program) [7]. Reasons for low engagement in youth-directed mental health apps include lack of perceived program value, limits on program accessibility (eg, within-program fees, limits on 24/7 access), and poor user experience (eg, high demands on users’ time) [4,16]. Thus, a need exists for digital mental health supports that (1) include evidence-based content, established in well-controlled trials; (2) show acceptability in naturalistic contexts (ie, outside of formal trials); (3) minimize demands on users’ time, given the high likelihood of accessing a digital intervention only once; and (4) are free of access barriers, such as program costs.

Single-session interventions (SSIs)—structured interventions, including one component of empirically supported treatments and requiring one encounter with a provider or program—could dramatically improve the acceptability and accessibility of digital mental health tools. Overall, SSI effects on youth psychopathology are slightly smaller than those observed for youth treatments lasting an average of 16 sessions (g=0.32 for single-session interventions [17], versus g=0.46 for multi-session interventions [17,18]. However, their brevity and flexible format magnify their potential public health impact [19]. Additionally, across placebo-controlled trials, self-administered online SSIs have reduced youth depression across 4-9 months in high-symptom and community youth samples [20-22]. These findings suggest the untapped potential of online SSIs to improve youth access to effective support.

In principle, online SSIs might overcome many challenges typical of traditional digital mental health tools. They are completable within one sitting, minimizing engagement burdens on users, and many are cost-free, publicly accessible, and include evidence-based intervention components. However, there have been no formal evaluations of the acceptability of online SSIs outside of controlled clinical trials. To gauge the promise and challenges to realizing the potential of online SSIs to benefit youth mental health, we must systematically evaluate usage patterns, perceived acceptability, and the short-term effects of online SSIs in naturalistic contexts.

Toward this goal, we conducted an open-access program evaluation of online SSIs for adolescent mental health, Project YES (Youth Empowerment & Support) [23], to evaluate the acceptability and initial effects of three free-of-charge, publicly available web-based SSIs for adolescent internalizing distress. In line with SSI design recommendations, each of these three SSIs was intended to target and strengthen adaptive beliefs about the self and the world that have been shown to predict youth internalizing distress.

The first SSI, Project Personality, teaches how and why people’s traits—including their symptoms—are malleable rather than fixed [20]. Project Personality aims to strengthen adolescents’ perceived control over their behavior and emotions while reducing hopelessness regarding a positive future change. Low perceived control and elevated hopelessness consistently predict the course and severity of youth internalizing problems [24-28]. Further, both perceived control and hopelessness are modifiable via brief intervention, making them ideal proximal SSI targets. In a recent placebo-controlled trial, Project Personality significantly improved perceived control over emotions and behavior in adolescents characterized as high-symptom [15], and larger proximal increases in perceived control following Project Personality predicted greater reductions in internalizing symptoms over time [29]. Thus, in the context of Project YES, we assessed Project Personality’s link with improvements in perceived control and hopelessness.

The second SSI, Project CARE, teaches how and why one can work towards acting with self-compassion in order to reduce self-hate systematically [30]. Self-hate and closely related constructs (ie, self-criticism) are linked with current and future internalizing problems in both youths and adults [31-35]. Preliminary evidence also suggests negative perceptions of the self, including self-hate, are modifiable through self-administered interventions as brief as 5-11 minutes [36-39]. Thus, within Project YES, we assessed Project CARE’s link with improvements in self-hate.

The third SSI, the ABC Project, is modeled after behavioral activation interventions targeting adolescent depression, which teach that engaging in valued activities can powerfully shape one’s mood [30,40]. The construct of agency—one’s self-perceived ability to initiate and work towards goals—is central to mechanisms thought to underlie behavioral activation for youth depression. Specifically, “agency” references an individual’s perceived capacity to (a) set behavioral goals, and (b) maintain or generate motivation to move toward those goals [41]. Behavioral activation for adolescent depression—including a one-session, therapist-delivered program [42]—has produced marked improvements in adolescents’ perceived agency and depression symptom severity, relative to control conditions [43-45] Thus, within Project YES, we assessed the ABC Project’s link with proximal improvements in agency.

Each 30-minute program was created per a routinely employed SSI design framework, informed by basic social-psychological research and detailed elsewhere [19], wherein youths (1) learn brain science that normalizes each program’s core concept; (2) are treated as “experts” and invited to help researchers learn about youths’ perspectives and challenges; (3) synthesize the program’s ideas using their own words, while offering advice to peers facing difficulties; (4) hear stories from peers who used the program’s content to overcome setbacks. Regardless of SSI selection, youths taking part in YES are invited to offer their “best, anonymous coping advice” to other teens coping with depression or anxiety; each receives the option to share this advice to a public “YES advice center.” This feature builds on research suggesting that helping or supporting peers can benefit an individual’s sense of self-efficacy, motivation, and psychosocial functioning [46-48].

All YES participants may complete anonymous pre- and post-program assessments of proximal outcomes that may be altered by SSIs (per prior recommendations for evaluating SSI effects; [19]) along with feedback on program acceptability. Using pre-SSI, post-SSI, and user-pattern data collected from YES participants ages 11-17 over 7 months, we investigated the acceptability of YES SSIs among youths, including completion rates and perceptions of each SSI’s utility. We also assessed the immediate effects of YES SSIs on interrelated and clinically relevant outcomes they are designed to target, each of which relates to youth internalizing problems (agency, perceived control, hopelessness, and self-hate, assessed using both standardized and study-specific metrics). Specifically, we examined usage-pattern variables (eg, SSI selection, SSI completion rates), user characteristics (age-range, sex, gender identity, race/ethnicity, depressive symptoms), and acceptability metrics to gauge which youths use YES; how and why they engage with it; and whether they view YES as valuable, helpful, and user-friendly. We also examined whether proximal, clinically relevant outcomes significantly improved from pre- to post-SSI, both across all YES programs and within each program. This nonexperimental, observational project represents a critical step in understanding the promise of online mental health SSIs, and the challenges to realizing that promise.

This nonexperimental study evaluated the perceived acceptability and short-term effects of Project YES, an open-access platform for youths offering three 30-minute, self-directed SSIs, each teaching a strategy for coping with internalizing distress. Regardless of SSI selection, youths who completed an SSI reported significant pre-to-post-program reductions in hopelessness (d_av=0.53; d_z=0.71), self-hate (d_av=0.32; d_z=0.61), perceived control (d_av=0.60; d_z=0.72) and agency (d_av=0.39; d_z=0.50). Youths who completed an SSI rated it as enjoyable, easy to understand, likely to help peers, and worth recommending to others, and there was no evidence for adverse SSI effects (eg, no youths reported feeling “much more hopeless” or “much less able to solve problems” after program completion). Based on largely overlapping confidence intervals for d_av and d_z, no evidence emerged for differential SSI effects on proximal outcomes.

Findings reinforce and extend evidence supporting the utility of SSIs for youth experiencing internalizing distress [19,20,53]. Past studies have raised the possibility that open-access, online SSIs might benefit youths experiencing elevated symptoms. However, no studies have tested their acceptability or utility in naturalistic settings (versus in controlled trials, which offer participation incentives, necessitate parental involvement, and prevent youth from choosing which SSIs they wish to receive). This study provides the first evidence that online SSIs may be acceptable—and potentially helpful—when delivered in the “real-world” as free, publicly available supports. Within-group post-SSI effects were modest; even so, the accessibility, cost-free nature, and brevity of YES suggest its public health value, particularly if available continuously and on a large scale. The self-selected youth sample reported elevated depressive symptoms (among all youths who started YES, SMFQ mean 17.06, SD 6.40, and among youths who completed a YES SSI, SMFQ mean 16.51, SD 6.34, both >50% higher than commonly used screening cut-offs for adolescent depression [69]), indicating the acceptability and possible utility of YES among youths with immediate clinical needs.

In addition to frequently reporting clinically elevated depressive symptoms, many youths accessing YES reported one or more marginalized identities, including sexual minority status (50.13% of users) and racial/ethnic minority status (53.28% of users). YES includes no exclusion or screening criteria—youths from these communities self-selected into participation—and no formal efforts were made to recruit members of specific groups. Thus, YES and similar platforms may represent efficient avenues for providing support to youths that may be likely to need, but unlikely to access traditional services. Simultaneously, more female than male adolescents self-selected into YES. This discrepancy may reflect higher rates of depression among adolescent girls versus boys, but it also fits with research suggesting that boys who are experiencing depression access treatment less often than girls [70]. Future work may focus on redesigning YES-like platforms that appeal to adolescents regardless of sex.

Regarding usability, more than 34% of youths who began an SSI finished it. This rate compares favorably with prior studies of “real-world” engagement with self-directed, tech-based psychological supports (1-28% retention) [15,70], and even with rates of retention in outpatient youth psychotherapy (premature drop-out rates range from 16-75%) [71,72]. However, Project YES is the first naturalistic evaluation of web-based, youth-directed SSIs; thus, further research is needed to gauge whether a 34% completion rate is typical of this type of program, as well as the degree to which this rate could be improved. Systematically testing strategies for further improving retention in YES-like platforms will be valuable—especially among older users (above age 14), for whom completion rates were lower than for younger users (ages 13 and younger). Retention may be improved by eliminating or minimizing questionnaires (all YES questionnaires are optional, but their presence may be a deterrence) and decreasing intervention length and iteratively re-testing ‘hyper-brief’ SSIs for acceptability and utility. Other revisions may include personalizing intervention content for youths of different age ranges or developmental stages and optimizing YES for smartphone-based completion (currently, YES is completable across internet-equipped devices but is optimized for desktop and laptop users).

No evidence emerged for differential SSI effects on hopelessness, perceived control, agency, or self-hatred, although each SSI was initially intended to target a different proximal outcome. Project CARE was designed to reduce self-hatred, Project Personality was designed to strengthen perceived control and combat hopelessness, and the ABC Project was intended to strengthen perceived agency over behavior. However, no evidence emerged for domain-specific effects across SSIs. This outcome, while quite preliminary, fits with existing evidence that change-mechanisms may be more similar than different across psychotherapies [19,73]. Here, each SSI was designed according to a common set of principles [19] and included several elements in common (eg, neuroscience-based psychoeducation; testimonials from scientists and peers; opportunities to offer advice to others), which themselves may promote a shared set of adaptive thinking styles.

A second possibility is that the constructs assessed in this study—and clinical psychology intervention research more broadly—have shown considerable overlap, both conceptually and statistically [74,75], and may not reflect entirely distinct constructs. Additional measurement-focused work is needed to determine the extent to which self-report assessments of agency, perceived control, hopelessness, self-hate, and numerous other “thinking styles” commonly studied in intervention research reflect genuinely distinct factors, versus features of a shared latent construct.

A third possibility involves the role of personal choice on the platform. YES users independently decide not only whether to participate, but which SSI to complete and whether to publicly share anonymous advice with peers. These opportunities to exert agency, common across YES SSIs, may contribute to similar cross-program outcomes, at least proximally. This possibility is especially relevant to adolescents, for whom autonomy and assertion are both highly motivating and key developmental tasks. Future work may formally test how personal choice and opportunities to develop autonomy shape adolescents’ receptivity and response to YES-like support—and to mental health treatment more broadly.

Study limitations suggest directions for future research. First, this study is nonexperimental, observational, and anonymous. All of these features are necessary given the study’s objectives (to evaluate acceptability and utility of SSIs in naturalistic settings), but results should be interpreted with caution. For instance, despite targeted social media-based advertising, it is impossible to determine with certainty that participants were sincere when reporting their age-ranges. Further, as in any non-randomized program evaluation, possible selection bias cannot be overlooked. For instance, youths who self-initiate and complete a given SSI may be those most likely to benefit from it; thus, present findings may not reflect the SSIs’ utility for all youths. Future randomized trials that proactively address selection bias are needed to unpack this possibility. Third, given the anonymous nature of YES, we could not follow-up with participants; however, prior trials suggest these and similar SSIs confer longer-term clinical benefits [19,42,53]. Additionally, our SSIs are available only in English at this time, limiting access for large portions of the global population. Translation and further pilot-testing are needed to begin gauging the cross-contextual, cross-cultural promise of YES and similar platforms.

Overall, results suggest that open-access, free of charge SSIs for adolescents ages 11-17 are acceptable; associated with proximal improvements in hopelessness, agency, perceived control, and self-hatred; and show no evidence for adverse effects. Overall, YES users were more likely to perceive some psychological benefits than none—either in hopelessness, problem-solving skills, or both. Certainly, YES-like platforms cannot and should not replace longer-term psychotherapies—but they may offer much-needed low-cost, easily accessible support to the many youths who might otherwise go without treatment. Future work may examine the broader-scale use of YES across cultures, integration of YES-like platforms with more intensive forms of support, and systematically examine the role of SSI choice in adolescents’ response to similar interventions.