Table 1.

Content of youth Internet interventions selected for review.

Citation	Quality index	Age	N; gender	Study type	Control	Setting/goal	Content	Outcomes between-groups effect size (95% CI)	Outcomes pre/post effect size (95% CI)
Depression studies
Hoek et al. (2011); CATCH-IT 6 month	25	17.4	83; 56.6% female	RCT	Motivational interviewing vs. Brief advice	Primary care, prevention	CBT, BA, IPT, community resiliency, videos, stories	CESD-10: ES = 0.12 (− 0.31–0.55); PHQ-A: ES = − 0.2 (− 0.63–0.23)	BA: CESD-10: ES = 1.13 (0.72–1.52); PHQ-A: ES = 0.57 (0.19–0.95); MI: CESD-10: ES = 0.93 (0.54–1.31); PHQ-A: ES = 0.77 (0.38–1.15)
Saulsberry et al. (2013a); CATCH-IT 1 year	25	17.2	58, 57% female	RCT	Motivational interviewing vs. Brief advice	Primary care, prevention	CBT, BA, IPT, community resiliency, videos, stories	CESD-10: ES = 0.08 (− 0.35–0.51); PHQ-A: ES = − 0.05 (− 0.48–0.38)	CESD-10: ES = 0.96 (0.63–1.17); PHQ-A: ES = 0.81 (0.49–1.12)
Richards et al. (2016); CATCH-IT 2.5 year	24.5	19.6	44; 59.09% female	RCT	Motivational interviewing vs. Brief advice	Primary care, prevention	CBT, BA, IPT, community resiliency, videos, stories	CESD-10: ES = 0.37 (− 0.24–0.96); PHQ-A: ES = 0.28 (− 0.35–0.90)	CESD-10: ES = 0.84 (0.4–1.27); PHQ-A: ES = 0.79 (0.35–1.22)
Ip et al. (2016); Grasp the Opportunity	21	14.6	257; 68.1% female	RCT	Website vs. Attention control	School, prevention	CBT, BA, community resiliency, videos, stories; IPT excluded	12 months: CESD-R: ES = − 0.36 (− 0.61 to − 0.11)	8 months: CESD-R: ES = 0.09 (− 0.12–0.30)
Poppelaars et al. (2016); SPARX game vs. Op Volle Kracht lessons	22.5	13.3	208; 100% female	RCT	OVK vs. SPARX vs. combined vs. monitoring control	Game, prevention	CBT, education	12 months vs. control RADS-2: ES = 0.28 (− 0.11–0.67); vs. OVK RADS-2: ES = 0.40 (0.00–0.79)	12 months: RADS-2: ES = 1.05 (0.63–1.46)
van der Zanden et al. (2012); Online Master Your Mood (MYM)	24	20.9	244; 84.4% female	RCT	MYM vs. waitlist control	Chat room, prevention	CBT, BA, future planning	ITT 3 months: CESD-D: ES = 0.94 (0.64–1.23); anxiety HADS: ES = 0.49 (0.24–0.75)	6 months: CESD-D: ES = 1.48 (1.19–1.76); anxiety HADS: ES = 0.92 (0.65–1.18)
Kramer et al. (2014); PratenOnline	23	19.5	263; 78.7% female	RCT	Website vs. Wait list control	Home, prevention	Solution-Focused Brief Therapy (SFBT) chat with online therapist	4.5 month Chat vs. WL CESD: ES = 0.79 (0.45–1.08)	7.5 months vs. baseline CESD: ES = 2.05 (1.75–2.34)
Deady et al. (2016); DEAL Project	24.5	21.7	104; 59.6% female	RCT	DEAL Project vs. Health Watch control	Home, early intervention	CBT, MI, education, behavioral activation, relaxation & coping, mindfulness	6 month PHQ-9: ES = 0.39	6 month PHQ-9: ES = 1.42
Stallman et al. (2016)	24.5	23	107; 92% female	RCT	LI-CBT vs. self-help info only	Telephone, prevention	LI-CBT: Behavioral activation, exposure therapy, problem solving, sleep hygiene, relapse prevention.	2 month DASS-Depression: ES = − 0.55; DASS-Anxiety: ES = − 0.496	2 month DASS-Depression: ES = − 0.755; DASS-Anxiety: ES = − 0.498
Taylor et al. (2016); Image and Mood (IaM)	23.5	20	206, 100% female	RCT	iCBT vs. wait-list control	Home, prevention	CBT, IPT, BA, stress management (relaxation training), problem solving, college transition, Discussion board.	Post-test: EDE-Q Global: ES = 0.31; EDI-Drive for Thinness: ES = 0.24; In subgroup of 27 depressed individuals at baseline, BDI-II: ES = 0.96	Post-test: EDE-Q Global: ES = 1.23 (0.93–1.52); BDI-II: ES = 0.19 (− 0.09–0.46)
Anxiety studies
Christensen et al. (2014); iChill	23	25.6	558; 80.6% female	RCT	5-Arm: iChill with and without email and phone vs. Health Watch Control with and without phone	Home, prevention	CBT, education, physical activity promotion, relaxation, mindfulness meditation	12 month GAD-7: ES = 0.31 (− 0.05–0.67); Post-test CES-D: ES = 0.66 (0.29–1.01)	12 month GAD-7: ES = 0.79 (0.45–1.13); Post-test CES-D: ES = 0.67 (0.34–0.99)
Calear et al. (2016); Y-Worri/E-couch Anxiety and Worry program	24.5	14.8	1767; 62.8% female	RCT	Externally-supported vs. Teacher-supported vs. Wait-list control	School, prevention	CBT, education, relaxation, physical activity	6 month e-GAD HS vs. control: GAD-7: ES = − 0.14 (− 0.28–0.00); SAS-A: ES = 0.23 (0.09–0.37); WEMWBS: ES = − 0.24 (− 0.38 −− 0.10)	None significant
Day et al. (2013)	25	23.5	66; 89.3% female	RCT	Immediate vs. Delayed-access	Self-help, prevention	CBT, coaching, relaxation, education. Featured stimulation through videos, audio files, pictures and activities.	6 week post-test DASS-21 Depression: ES = 0.25 (0.06–1.05), Anxiety: ES = 0.67 (0.16–1.15), Stress: ES = 1.27 (0.73–1.78) maintained at 6 month f/u, w/o a sig. difference	6 week post-test DASS-21 Depression: ES = 1.13 (0.60–1.63), Anxiety: ES = 1.17 (0.63–1.68), Stress: ES = 0.15 (− 0.33–0.64)
De Voogd et al. (2016)	23.5	14.4	340; 57.6% female	RCT	Dot probe vs. visual search-based attentional training vs. 2 placebo controls	Home, early intervention	Visual search & dot-probe attention training	6-month vs. SCARED: ES = 0.14 (− 0.23–0.5); 6-months vs. training CDI: ES = 0.01 (− 0.36–0.37); 12-month vs. RSES: ES = 0.14 (− 0.23–0.5)	6-month vs. SCARED: ES = 0.33 (0.08–0.58); 6-month vs. CDI: ES = 0.43 (0.18–0.68); 12-month vs. RSES: ES = 0.48 (0.13–0.23)
Tillfors et al. (2011)	24.5	16.5	19; 89% female	RCT	iCBT vs. wait-list control	Self-help, early intervention	Education, cognitive restructuring, exposure.	Posttest: Social anxiety LSAS-SR Fear: ES = 1.48; LSAS-SR Avoidance: ES = 1.13; Social phobia SPSQ-C: ES = 1.28; Depression MADRS-S: ES = 1.39; Anxiety BAI: ES = 1.47	Posttest: Social anxiety LSAS-SR Fear: ES = 0.91; LSAS-SR Avoidance: ES = 0.55; Social phobia SPSQ-C: ES = 1.06; Depression MADRS-S: ES = 1.12; Anxiety BAI: ES = 0.97
Räsänen et al. (2016); The Student Compass/Opiskelijan Kompassi	24	24.29	68; 85.3% female	RCT	Online Acceptance and Commitment Therapy (iACT) vs. Waitlist control	Home, coach-guided, early intervention	Education, wellbeing tasks, metaphors, coaching, relaxation, case studies. Engagement through downloadable audio MP3s, educational videos and exercises. Coaches tailored program to students' individual needs.	Post-test: Depression BDI-II: ES = 0.69; Stress PSS: ES = 0.54; Wellbeing MHC-SF: ES = 0.46; Mindfulness skills FFMQ: ES = 0.49; Coherence OLQ-13: ES = 0.53	Post-test: Depression BDI-II: ES = 1.12; Stress PSS: ES = 0.76; Wellbeing MHC-SF: ES = 0.61; Mindfulness skills FFMQ: ES = 0.62; Coherence OLQ-13: ES = 0.52
Cox et al. (2009); So You've Been In an Accident	23	7–16	85; 26 females, 59 males	RCT	Website and booklet vs. Assessment only	Home, early intervention	CBT, resiliency, relaxation, coping, problem solving, reflection	TSCC-A anxiety subscale: ES = − 0.33 (− 0.86–1.9)	None significant
Ruggiero et al. (2015); Bounce Back Now (BBN)	23	14.5	2000; 51% female	RCT	BBN vs. BBN + ASH (Adult Self Help) vs. Assessment only	Home, Prevention	Education, PTSD (exposure, coping, anxiety management), Depression (BA), Substance abuse (CBT, motivational enhancement). Used text, graphics, videos, quizzes and animations to engage users.	12 month PTSD: ES = 0.19 (− 0.03–0.41); Depression: ES = 0.19 (− 0.03–0.41)	12 month PTSD: ES = 0.52 (0.34–0.70); Depression: ES = 0.47 (0.29–0.65)
Lenhard et al. (2014); BiP OCD (BarnInternetProjektet)	Not a control study; index not assessed	14.4	21; 61.9% female	Clinical trial	None	Home, Treatment	CBT and education delivered through film, exercises, animations and interactive scripts.	N/A (only one group)	Post-test CY-BOCS: ES = 2.29 (1.5–3.07); 6 month CY-BOCS: ES = 2.35 (1.5–3.18); No changes between 3 and 6 months. Pre/6-month ES = 2.35.
Turner et al. (2014)	24.5	14.35	72; 52.8% male	RCT	Telephone-CBT vs. CBT (non-inferiority)	Telephone, treatment	CBT, exposure with response prevention (E/RP), relapse prevention, psychoeducation	6 month CY-BOCS: ES = − 0.13 (− 0.59–0.34)	6 month CY-BOCS: ES = 1.97 (1.38–2.51); 6 month CDI-Y: ES = 1.13 (0.62–1.61)