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Mental disorders are highly prevalent and associated with considerable disease burden and personal and societal costs. However, they can be effectively reduced through prevention measures. The Internet as a medium appears to be an opportunity for scaling up preventive interventions to a population level.
The aim of this study was to systematically summarize the current state of research on Internet-based interventions for the prevention of mental disorders to give a comprehensive overview of this fast-growing field.
A systematic database search was conducted (CENTRAL, Medline, PsycINFO). Studies were selected according to defined eligibility criteria (adult population, Internet-based mental health intervention, including a control group, reporting onset or severity data, randomized controlled trial). Primary outcome was onset of mental disorder. Secondary outcome was symptom severity. Study quality was assessed using the Cochrane Risk of Bias Tool. Meta-analytical pooling of results took place if feasible.
After removing duplicates, 1169 studies were screened of which 17 were eligible for inclusion. Most studies examined prevention of eating disorders or depression or anxiety. Two studies on posttraumatic stress disorder and 1 on panic disorder were also included. Overall study quality was moderate. Only 5 studies reported incidence data assessed by means of standardized clinical interviews (eg, SCID). Three of them found significant differences in onset with a number needed to treat of 9.3-41.3. Eleven studies found significant improvements in symptom severity with small-to-medium effect sizes (d=0.11- d=0.76) in favor of the intervention groups. The meta-analysis conducted for depression severity revealed a posttreatment pooled effect size of standardized mean difference (SMD) =−0.35 (95% CI, −0.57 to −0.12) for short-term follow-up, SMD = −0.22 (95% CI, −0.37 to −0.07) for medium-term follow-up, and SMD = −0.14 (95% CI, -0.36 to 0.07) for long-term follow-up in favor of the Internet-based psychological interventions when compared with waitlist or care as usual.
Internet-based interventions are a promising approach to prevention of mental disorders, enhancing existing methods. Study results are still limited due to inadequate diagnostic procedures. To be able to appropriately comment on effectiveness, future studies need to report incidence data assessed by means of standardized interviews. Public health policy should promote research to reduce health care costs over the long term, and health care providers should implement existing, demonstrably effective interventions into routine care.
Mental disorders remain highly prevalent worldwide with lifetime prevalence rates varying between 12.0% in Nigeria and 47.4% in the United States [
Because care and treatment options and results remain limited [
There are 3 different types of prevention. Universal prevention is focused on the general population (including those without special risk factors). The focus of selective prevention is on subgroups at risk of developing a (mental) disorder (increased risk compared with the average population), whereas indicated prevention targets subgroups who show subthreshold symptoms (ie, not fulfilling full diagnosis criteria) [
Regardless of the type of prevention, prevention measures should lead to a substantial reduction in the incidence of the target mental disorder. Consequently, for assessing the effectiveness of preventive interventions, an initial disorder-free target population is needed. In addition, current incidence data collected by means of standardized interviews (eg, Structured Clinical Interview for DSM Disorders [SCID], MINI) are required [
Recent reviews and meta-analyses indicated that prevention of mental disorders is feasible and can lead to a substantial “impact,” that is, reduction of incidence rates of mental disorders [
The Internet as medium for delivery has been identified as an appropriate way to scale up preventive interventions [
There are few reviews and meta-analyses to date summarizing empirical findings on IMIs for the prevention of mental disorders. The literature yields reviews on prevention of eating disorders (EDs) [
With regard to content, substance-related and addictive disorders prevention programs are often focused on health behaviors and health promotion, rather than on psychotherapeutic variables [
This systematic review has been registered in the PROSPERO register (registration number CRD42015026781). It was conducted according to the PRISMA guidelines [
Studies were eligible for inclusion if they (1) focus on an adult target population, who (2) were without a diagnosis of the target mental disorder at baseline (primary prevention intervention). (3) Mental disorders had to be assessed by means of standardized interviews (eg, SCID [
(4) Interventions needed to be based on psychological interventions. The definition of “psychological intervention” was taken from Kampling et al [
(6) Studies had to include a control group. This could be either (enhanced) usual care, wait-list control group, another intervention, or no treatment.
(7) Studies examining onset of disorder were included, defined as percentage of persons who developed the mental disorder under study from pre- to follow-up-assessment. In addition to data from standardized clinical interviews (eg, SCID-IV [
(9) Only randomized controlled trials (RCTs) that are available in full text will be eligible for this review. For an overview of the eligibility criteria, see
Eligibility criteria.
No. | Item | Inclusion | Exclusion |
1 | Population | Adults (≥ 18 years) | Children and adolescents (< 18 years) |
2 | Prevention | Universal, selective, or indicated prevention | Parts of the population already affected at baseline |
3 | Assessment | Instrument with standardized cut-offs for clinical significance or symptom severity (> moderate symptomatology) | Descriptive symptom-oriented instruments without standardized cut-offs |
4 | Prevented disorder | Mental disorder other than substance-related/addictive disorder | Other types of disorders; substance-related/addictive disorders |
5 | Intervention | Web-based, psychological, preventive | Not Web-based, no psychological principles, treatment rather than prevention |
6 | Control group | Waiting list, other treatment, placebo, care as usual | No control group |
7 | Outcomes | Onset, Number Needed to Treat, Incidence Rate Ratio, severity | Other outcomes (no statements possible about preventive effect) |
8 | Follow-up | At least 3 month follow-up assessment | No or < 3-month follow-up assessment |
9 | Study design | Randomized controlled trial | No randomized controlled trial (eg, cross-sectional studies, case studies, or case reports) |
A systematic database search was conducted. Databases included are The Cochrane Central Register of Controlled trials (CENTRAL), PsycINFO, and MEDLINE (search date August 17, 2015). A sensitive search strategy was developed and applied for each database [
When indicated, study authors have been contacted to obtain further information to clarify study characteristics. When study protocols were identified without subsequent publication of results, authors have been contacted to obtain missing or unpublished data and determine eligibility for inclusion in this review.
The selection of papers was conducted by 2 independent reviewers (LS, LR). In the first step, authors screened all titles and abstracts yielded by the database search. In the second step, the full texts of the selected articles were retrieved and screened in terms of the aforementioned eligibility criteria. Reference lists of all articles included in the study were screened in the same way. Disagreement at both screening levels was resolved by discussion. Concurrent validity of the 2 reviewers was examined.
PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow chart of included studies.
The following data items were extracted for each study: (1) study identification items (first author, year of publication), (2) study design characteristics (sample size, control group, type of assessments, length of follow-up assessments), (3) intervention characteristics (name, type, duration, level of human support or guidance), (4) prevention characteristics (type, prevented disorder), (5) dropout rate, (6) target population (eg, risk group), and (7) clinical outcomes (onset and/or severity of disorder including means, variances, as well as effect sizes). In case of deficient or missing outcome data, authors were contacted and data were requested. To ensure accuracy, a second reviewer rechecked the extracted data.
To evaluate the quality of evidence, the risk of bias was assessed for each study according to the Cochrane Collaboration’s tool for assessing risk of bias in RCTs [
If onset data were available, IRR and NNT were calculated. When there were at least 5 studies with available severity data within one disorder (as primary and secondary outcome), a meta-analytically pooled effect size was calculated, and effect sizes were illustrated in forest plots. Meta-analyses were conducted using Review Manager 5.3 (Cochrane Collaboration, 2014). Standardized mean differences (SMDs) with 95% CIs were computed for all continuous outcomes. Random-effects meta-analyses were performed to compute overall estimates of treatment outcome. The
The systematic database search yielded 1600 hits. After removing duplicates, screening titles, abstracts, and full text papers for inclusion, conducting a reference search, searching trial registers for eligible studies and contacting authors, a total of 17 studies met eligibility criteria and were included in the review. The selected studies targeted the prevention of EDs, depression, anxiety, post-traumatic stress disorder, generalized anxiety disorder (GAD), or a combination of these mental disorders [
Five of 17 studies were classified as having a high risk of bias and the remaining 12 studies were classified as having a low risk of bias (
Regarding dropout rate (4a), only 7 studies met the predetermined criterion (≤20% for short-term follow-ups, ≤ 30% for long-term follow-ups). Ten of the included studies reported the use of an intention-to-treat analysis (4b); the remaining studies were categorized as unclear. Two studies reported results incompletely [
To evaluate the risk of certain biases (selection, performance, detection, and attrition bias), the criteria can be grouped into randomization, blinding, outcome, and withdrawal criteria. Selection bias could only be ruled out in 3 studies [
Performance bias could be present in every study. As mentioned previously, blinding was only insufficiently possible for all studies. Hence, criteria concerning expectation and performance effects (3a – blinding of participants, 3b – blinding of personnel, 6b – no cointerventions, 6c – compliance) were never completely fulfilled.
Concerning detection bias, 3 studies [
Three studies [
Many studies administered measures of a variety of mental disorders. Hereinafter included studies are arranged by their main focus. For an overview of all included studies, see
Risk of bias assessment.
Study | Sequence generationa | Allocation concealmentc | Blinding | Incomplete |
Selective outcome reportingi | Other threats to validity | Risk of Biasn | |||||||
Participantsd | Personnele | Outcome |
Dropoutg | ITTh | Similar groupsj | Cointerventionsk | Compliancel | Timingm | ||||||
Bantum et al [ |
||||||||||||||
Yesb | Unclear | No | No | No | Yes | Unclear | Yes | No | Yes | Yes | No | High | ||
Beatty et al [ |
||||||||||||||
Yes | Yes | Unclear | No | No | Yes | Yes | Yes | Yes | Yes | No | Yes | Low | ||
Christensen et al [ |
||||||||||||||
Yes | Yes | Unclear | No | No | No | Yes | No | No | Yes | Yes | Yes | Low | ||
Christensen et al [ |
||||||||||||||
Yes | Yes | No | No | Yes | No | Yes | Yes | Yes | Yes | Yes | Yes | Low | ||
Imamura et al [ |
||||||||||||||
Yes | Yes | No | No | No | No | Yes | Yes | Unclear | Yes | No | Yes | Low | ||
Jacobi et al [ |
||||||||||||||
Yes | Unclear | No | No | No | Yes | Unclear | No | Unclear | Yes | Yes | Yes | Higho | ||
Jacobi et al [ |
||||||||||||||
Yes | Unclear | No | No | Yes | No | Unclear | Yes | Unclear | Yes | Yes | Yes | Low | ||
Mitchell et al [ |
||||||||||||||
Yes | Yes | Yes | No | No | No | Yes | Yes | Unclear | Yes | No | Yes | Highp | ||
Mouthaan et al [ |
||||||||||||||
Yes | Yes | No | No | Yes | No | Yes | Yes | Unclear | Yes | Yes | Yes | Low | ||
Musiat et al [ |
||||||||||||||
Yes | Yes | No | No | No | No | Unclear | Yes | Yes | Yes | No | Yes | Low | ||
Powell et al [ |
||||||||||||||
Yes | Yes | No | No | No | No | Yes | Yes | Yes | Yes | No | Yes | Low | ||
Proudfoot et al [ |
||||||||||||||
Yes | Yes | No | No | No | No | Yes | Yes | No | Yes | No | Yes | Highq | ||
Stice et al [ |
||||||||||||||
Yes | Unclear | Yes | No | Yes | Yes | Unclear | Yes | Yes | Yes | Yes | Yes | Low | ||
Taylor et al [ |
||||||||||||||
Yes | Unclear | No | No | Yes | Yes | Unclear | Yes | No | Yes | Yes | No | Highr | ||
Thompson et al [ |
||||||||||||||
Unclear | Unclear | No | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Low | ||
Winzelberg et al [ |
||||||||||||||
Unclear | Unclear | No | No | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Low | ||
Zabinski et al [ |
||||||||||||||
Unclear | Unclear | No | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Low |
aRandom unpredictable assignment sequence.
bYes = Criterion has been met (low risk of bias); No = Criterion has not been met (high risk of bias)
cAssignment generated by an independent person who is not responsible for determining the eligibility of participants.
dIntervention and control group are indistinguishable for the participants.
eIntervention and control group are indistinguishable for the care providers.
fIntervention and control group are indistinguishable for the outcome assessors (for patient reported outcomes, it is adequate if patients are blinded).
gDropout must be described and reasons must be given, for short term follow-ups (eg, 3 months) 20%, for long term follow-ups (eg, ≥ 6 months) 30% should not be exceeded.
hITT: intention-to-treat; all randomized patients are reported and analyzed in the group they were allocated to by randomization.
iResults of all pre-specified outcomes have to be adequately and completely reported.
jGroups should not differ significantly at baseline regarding demographics and outcomes.
kThere are no cointerventions or they are similar between intervention and control groups.
lAcceptable compliance with the intervention (eg, intensity, duration, number, frequency of sessions).
mIdentical timing of outcome assessments for intervention and control groups.
n≥ 6 x “Yes” and no serious flaws indicates an overall low risk of bias; < 6 x “Yes” or serious flaws indicates an overall high risk of bias.
oSerious flaw: Results of diagnostic interviews not reported.
pSerious flaw: Very high dropout and very low compliance rate.
qSerious flaw: Baseline differences between groups, very low compliance.
rSerious flaw: Baseline differences between groups in several scales.
Characteristics of included studies
Study | Prevention |
Prevented |
Targeted |
Program |
Intervention |
Conditions | Sample |
Instrument | Follow-up |
Drop-outa | ITTb |
Bantum et al [ |
|||||||||||
Selective | Depression | Adult |
Surviving |
Assisted |
1. STC |
n=352 |
PHQ-9c | 6 | 13.9% | Unclear | |
Beatty et al [ |
|||||||||||
Selective | PTSDd |
Adult |
Cancer |
Self-guided |
1. CCO |
n1=30 |
DASSf |
4.5 |
8.3% | Yes | |
Christensen et al [ |
|||||||||||
Indicated | GADh |
Young |
iChill | Active website (CBT) + email |
1. Active website |
n1 = 111 |
GAD-7i |
6 |
52.69% | Yes | |
Christensen et al [ |
|||||||||||
Indicated |
Depression | Adult |
SHUTi | Modular |
1. SHUTi |
n1=574 |
PHQ-9 |
1.5 |
56.1% | Yes | |
Imamura et al [ |
|||||||||||
Indicated | Depression | Workers with |
Internet CBT program (iCBT) | Guided |
1. iCBT |
n1=381 |
BDI-IIl |
12 | 32.9% | Yes | |
Jacobi et al [ |
|||||||||||
Selective | Eating |
Female |
StudentBodies (SB) | Structured |
1. SB |
n1=50 |
EDE-Qn |
3 | 6.00% | Unclear | |
Jacobi et al [ |
|||||||||||
Indicated | Eating |
Women |
StudentBodies+ |
Structured CBT + |
1. SB+ |
n1=64 |
EDE-Q |
6 | 18.3% | Unclear | |
Mitchell et al [ |
|||||||||||
Universal | Anxiety |
Adult |
Strength-Intervention | Self-guided |
1. Strength-Intervention |
n1=48 |
DASS | 3 | 78.4% | Yes | |
Mouthaan et al [ |
|||||||||||
Indicated | PTSD |
Injury |
Trauma |
Self-guided Internet-based CBT |
1. Trauma TIPS |
n1=151 |
HADSq |
1 |
53.7% | Yes | |
Musiat et al [ |
|||||||||||
Universal | Anxiety |
University students | Personality and |
Automated transdiagnostic trait focused Web-based intervention |
1. PLUS |
n1=519 |
PHQ |
3 | 61.7% | Unclear | |
Powell et al [ |
|||||||||||
Universal | GAD | Users |
MoodGYM | Self-directed |
1.MoodGYM |
n1=1534 |
CES-D |
3 | 50.2% | Yes | |
Proudfoot et al [ |
|||||||||||
Indicated | Anxiety |
Adults |
myCompass | Automated intervention + |
1. MyCompass |
n1=242 |
DASS | 3 | 51.4% | Yes | |
Stice et al [ |
|||||||||||
Selective | Eating |
Female |
eBody Project (eBP) | Self-guided |
1. eBP |
n1=19 |
BDIt |
12 |
4.7% | Unclear | |
Taylor et al [ |
|||||||||||
Selective | Eating |
College |
StudentBodies (SB) | Structured |
1. SB |
n1=244 |
CES-D |
12 |
12.3% | Unclear | |
Thompson et al [ |
|||||||||||
Indicated | Depression | Mild- to |
Using |
Telephone- |
1. UPLIFT |
n1=64 |
BDI |
2 |
15.6% | Yes | |
Winzelberg et al [ |
|||||||||||
Selective | Eating |
Female |
Student |
Structured |
1. SB |
n1=31 |
EDE-Q | 3 | 26.7% | Yes | |
Zabinski et al [ |
|||||||||||
Selective | Eating |
College |
Chat room | Private chat |
1. Chat room |
n1=30 |
EDE-Q | 4.5 | 3.3% | Yes |
aDropout-rate from baseline to the longest available follow-up.
bITT: Intention-to-treat-analysis
cPHQ: Personal Health Questionnaire depression scale
dPTSD: Posttraumatic Stress Disorder
eCBT: Cognitive Behavioral Therapy
fDASS: Depression Anxiety Stress Scale
gPSS: PTSD Symptom Scale
hGAD: Generalized Anxiety Disorder
iGAD-7: Generalized Anxiety Disorder questionnaire – 7
jMINI: Mini-International Neuropsychiatric Interview
kCES-D: Center for Epidemiological Studies Depression scale
lBDI-II: Beck Depression Inventory II
mCIDI: WHO Composite International Diagnostic Interview (Web-based, self-administered version)
nEDE-Q: Eating Disorder Examination Questionnaire
oSCID: Structured Clinical Interview for DSM Disorders
pEDI-2: Eating Disorder Inventory
qHADS: Hospital Anxiety and Depression Scale
rCAPS: Clinician-Administered PTSD Scale
sEDDS: Eating Disorders Diagnostic Scale
tBDI: Beck Depression Inventory
uEDDI: Eating Disorder Diagnostic Interview
vEDE-I: Eating Disorder Examination Interview
wmBDI: Modified Beck Depression Inventory
xNDDI-E: Neurological Disorders Depression Inventory in Epilepsy
The systematic search yielded 6 studies on eating disorders. Four evaluated the effectiveness of StudentBodies, an Internet-based intervention for young women at risk of developing an eating disorder or with subthreshold eating disorders. StudentBodies was originally developed and evaluated in the United States [
Also inspired by StudentBodies, Zabinski et al [
Stice et al [
The search yielded 3 prevention programs focused on the prevention of depression. Surviving and Thriving with Cancer [
The guided Internet-based CBT program (iCBT) by Imamura et al [
Thompson et al [
The 6-week Web-based insomnia program SHUTi by Christensen et al [
Two studies focused on combined anxiety and depression. A self-guided intervention promoting well-being in a general population was tested by Mitchell et al [
MyCompass [
There were 2 studies that focused on post-traumatic stress. The self-guided Trauma TIPS [
Cancer Coping Online, a self-guided Web-based CBT program for reducing distress in patients currently receiving cancer treatment, was evaluated by Beatty et al [
The search yielded 2 studies on GAD. MoodGYM [
Musiat et al [
Five studies reported incidence data allowing for the calculation of onset, IRR, and NNT (see
Incidence, onset, incidence rate ratio (IRR), number needed to be treated (NNT)
Study | Disorder | Number of onsets | Follow-up | IRRc | NNTd | |
IGa | CGb | |||||
Christensen et al [ |
Depression | N=9 |
N=13 |
6 months | 0.87 | 160 |
Imamura et al [ |
Depression | n=3 |
n=15 |
12 months | 0.23 | 23.5 |
Thompson et al [ |
Depression | n=0e |
n=6 |
2 months (pre–post) | 0.09 | 9.3 |
Taylor et al [ |
Eating Disorders | n=8 |
n=13 |
12 months | 0.63 | 41.3 |
Christensen et al [ |
GADf | n=10 |
n=6 |
6 months | 1.29 | −76.8 |
aIG: intervention group
bCG: control group
cIRR: incidence rate ratios
dNNT: number needed to treat
eA correction of 0.5 was added to the zero incidence in the intervention group for IRR calculation.
fGAD: Generalized Anxiety Disorder
Severity data were extracted for all included studies. Eleven studies found significant effects on symptom severity with small-to-large effect sizes (
For the meta-analysis of depression interventions, we included studies with depression as a primary and secondary outcome. In cases of multiple active groups, only the main intervention sample was analyzed [
For short-term follow-up, our calculations yielded an effect size of SMD = −0.35 (95% CI, −0.57 to −0.12,
The effects of preventive interventions on symptom severity of depression at short-term FU—comparison experimental versus control group.
The effects of preventive interventions on symptom severity of depression at medium-term FU—comparison experimental versus control group.
The effects of preventive interventions on symptom severity of depression at long-term FU—comparison experimental versus control group.
An ICTRP search for ongoing trials yielded 570 records for 560 trials (years 2005-2015). Sixty-two records were selected as likely being relevant. Most of those were planned studies on symptom severity as a secondary outcome and with different study purposes. Eleven records aimed to assess severity data and had an explicit preventive goal. Targeted conditions were mostly mood and anxiety disorders. Seven studies planned to use clinical interviews for diagnostics or to explicitly gather incidence data. Three studies of those studies were already published, one of them is included in this review [
This review and meta-analysis systematically summarizes previous research on Internet-based interventions for the prevention of mental disorders. It therefore exceeds the informative value of existing reviews (eg, [
Seventeen RCTs were included in this review and described in detail. Results are in line with previous meta-analyses, showing that indicated and selective prevention is more common than universal prevention [
Quality assessment suggests that 5 included studies have a high risk of bias. Some biases are inevitable (eg, blinding not possible for psychological interventions). Others, such as biases due to inappropriate randomization, can and should be avoided. Of note, 3 studies were classified as having high risk of bias solely due to a serious flaw. Reasons for study classification as having a serious flaw included baseline differences between intervention and control groups [
Three of 5 studies reporting incidence data provided evidence for a preventive effect of the investigated interventions [
Nevertheless, severity data show positive effects of interventions in 11 of 17 studies with small-to-medium effect sizes. The best evidence was found for ED and depression. Beintner et al [
Our meta-analysis on IMIs for depression showed an overall small but significant reduction in symptom severity. As mentioned before, this demonstrates an effect of IMIs on the treatment of subclinical depression; a subsequent reduction of incidence can only be assumed, as most included studies did not report incidence data. Because of moderate to high levels of heterogeneity, the actual effect size values should be interpreted with caution. Nevertheless, heterogeneity results from estimates showing the same direction of effect favoring interventions over control groups.
In summary, evidence was found for effectiveness of interventions for EDs, depression, and anxiety. Internet-based interventions can be considered effective in reduction of subthreshold symptomatology and may also be suitable for preventing the onset of mental disorders over the long term. Depression and anxiety are of particular clinical relevance against the background of prevalence rates: as mentioned, anxiety disorders, insomnia, and major depression are the most common mental disorders in the European Union [
A number of potential limitations and challenges regarding this study should be acknowledged. As usual for reviews and meta-analyses, publication bias [
Another limitation concerns the inclusion of studies that reported mean scores only and did not clearly state that participants did not exceed clinical cutoffs at baseline (second exclusion criterion). This became evident after contacting authors to obtain raw data and subsequently computing incidence and onset rates if they had not already been reported. Four of those studies [
One major challenge of this broad review was the handling of variability between studies. Although heterogeneity was expected, and even welcomed to map out the broad scope of existing e-mental health prevention interventions, it must be taken into account when interpreting the findings. There are several sources of heterogeneity. First, this review was not restricted to one mental disorder but included a number of clinical conditions. Second, methods to determine the clinical status of participants, such as structured clinical interviews or self-report questionnaires, differed between studies. Third, intervention contents were different. As mentioned previously, most interventions were based on CBT, but other intervention types were included as well. Fourth, study design caused heterogeneity, due to different types of control groups, varying follow-up assessment periods and different sample sizes. For the meta-analysis, pooled effect sizes were calculated for depression and grouped into 3 follow-up periods. Nevertheless, different sample sizes can lead to overweighting of the larger size studies.
To gain insight into requirements for future research, limitations of the presented studies should be considered. First, the 5 included incidence studies were planned with preventive goals and used standardized clinical interviews for valid diagnosis. The remaining studies were often planned for other purposes (eg, improving well-being), and mental disorder symptoms were gathered by means of self-report questionnaires. Therefore, additional incidence studies using valid diagnostic instruments are needed, especially in light of the ICTRP search results, which revealed that very few incidence studies are planned in the near future.
Second, the evidence base is limited to a handful of disorder groups specifically EDs, depression and anxiety. Research could expand to the missing subfields, for which Internet-based prevention could be applicable. It is noteworthy that one ongoing trial targets prevention of psychosis [
Third, this is the first exhaustive review on Internet-based prevention for mental disorders in adults. One could expand the scope to additional domains and populations, for instance to relapse prevention in mentally ill persons. As there are already several studies on this topic (eg, [
Fourth, most Internet-based interventions included in this review had no additional human support component (ie, unguided). Although this results in a reduction of initial costs, it is also accompanied by a reduction of effectiveness [
Internet-based interventions can be effective in the primary prevention of mental disorders. The body of research is still limited to a few mental disorders (EDs, depression, anxiety disorders). Therefore, further high-quality studies are required, using standardized clinical interviews and gathering incidence data in long-term follow-ups. Because of the advantages of Internet-based interventions such as cost-effectiveness, availability, and flexibility [
cognitive behavioral therapy
Cochrane Central Register of Controlled Trials
control group
eating disorder
generalized anxiety disorder
International Clinical Trials Registry Platform
intervention group
Internet- and mobile-based intervention
Information technology
incidence rate ratio
mean difference
Medical Subject Heading
number needed to be treated
Preferred Reporting Items for Systematic Reviews and Meta-Analyses
post-traumatic stress disorder
randomized controlled trial
structured clinical interview for DSM disorders
The authors would like to thank Yannik Terhorst for proofreading of the manuscript and Mary Wyman for language editing. The article processing charge was funded by the German Research Foundation (DFG) and the Albert Ludwigs University Freiburg in the funding program Open Access Publishing. Personnel resources granted Federal Ministry of Education and Research, Germany (project: Effectiveness of a guided web-based intervention for depression in back pain rehabilitation aftercare, grant number: 01GY1330A) supported the realization of this review. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
None declared.
LS, LR, and HB were involved in the concept and design of the study. LS and LR had major contributions to data extraction and analysis. All authors had major contributions to the write-up and editing of the manuscript and read and approved the final manuscript.