Abstract
Background: Access to mental health care is limited. Internet-based interventions (IBIs) may help bridge that gap by improving access especially for those who are unable to receive expert care. Aim: This review explores current research on the effectiveness of IBIs for depression and anxiety. Results: For depression, therapist-guided cognitive behavioral therapy (CBT) had larger effect sizes consistently across studies, ranging from 0.6 to 1.9; while stand-alone CBT (without therapist guidance) had a more modest effect size of 0.3–0.7. Even other interventions for depression (non-CBT/non-randomized controlled trial (RCT)) showed modestly high effect sizes (0.2–1.7). For anxiety disorders, studies showed robust effect sizes for therapist-assisted interventions with effect sizes of 0.7–1.7 (efficacy similar to face-to-face CBT) and stand-alone CBT studies also showed large effect sizes (0.6–1.7). Non-CBT/Non-RCT studies (only 3) also showed significant reduction in anxiety scores at the end of the interventions. Conclusion: IBIs for anxiety and depression appear to be effective in reducing symptomatology for both depression and anxiety, which were enhanced by the guidance of a therapist. Further research is needed to identify various predictive factors and the extent to which stand-alone Internet therapies may be effective in the future as well as effects for different patient populations.
Introduction
Although there is an increasing recognition of mental health issues around the world, accessibility to healthcare has been a key problem, with specialist access in psychiatry restricted to only about 10% (Wang et al., Citation2005). In fact, less than a third of all patients get access to basic care (e.g. seeing a primary-care physician), and the majority (two-thirds) receives no access at all (Wang et al., Citation2005). Developing appropriate support strategies for the vast majority, especially for highly prevalent problems, such as mood disorders, anxiety disorders and substance-use disorders, is a critical public health challenge. Online interventions have the potential to address this gap for a variety of disorders and problems, including substance abuse, depression, anxiety, lack of social skills and panic disorders (Barak, Hen, Boniel-Nissim, & Shapira, Citation2008; Marks, Cavanagh, & Gega, Citation2007). Delivery of interventions through the Internet provides anonymity and easy accessibility, therefore making it a suitable option for clients with psychological problems to receive help. In addition, they can avoid the stigma incurred by seeing a therapist (Gega, Marks, & Mataix-Cols, Citation2004), and can obtain treatment at any time or place, work at their own pace, and review the material as often as desired.
With Internet-based interventions (IBIs), clients can be supported in a variety of different ways, from screening to structured assessments, and from guided self-help to sophisticated expert-system-based treatments. The level of therapist involvement can vary from no assistance or minimal therapist contact by e-mail or telephone, to the amount of involvement as seen in classic individual therapy. Thus, it may be possible to reduce the therapist involvement time while maintaining efficacy (Wright et al., Citation2005). Furthermore, it may be possible to reach people through the Internet who might not otherwise receive treatment for their conditions. These advantages outline the popular support that online interventions have received. Yet, the effectiveness of online interventions still needs to be evaluated in order to gain a clear understanding of their potential cost–benefit ratio.
In the past, there have been some excellent systematic and meta-analytical reviews evaluating online interventions. Griffiths and colleagues (Griffiths, Farrer, & Christensen, Citation2010) evaluated 26 randomized controlled trials (RCTs) on depression and anxiety interventions, excluding all other kinds of studies. They found an effect size difference ranging from 0.42 to 0.65 for depression interventions and 0.29–1.74 for anxiety interventions. Another review which evaluated online interventions for depression and anxiety concentrated on children and adolescents (Calear & Christensen, Citation2010). This paper compared four intervention programs describing eight different studies. Although it described each of the programs, it did not evaluate for effectiveness. An earlier meta-analysis of 12 RCTs in 2007 (Spek, Cuijpers et al., Citation2007) evaluated online interventions for depression and anxiety through a mixed effects analysis and found small mean effect sizes for depression (0.32) compared to larger ones for anxiety (0.96). Therapist-supported interventions also had larger effect sizes than the non-therapist ones.
Another quantitative review (Reger & Gahm, Citation2009) which combined computer-based and Internet-based cognitive behavioral therapy (CBTs) (ICTs) evaluated 19 RCTs and observed ICT was superior to wait-list and placebo assignment across outcome measures (ds = 0.49–1.14), with effects of ICT being equal to therapist-delivered treatment across anxiety disorders. Titov (Citation2011), in his systematic review of 13 studies that dealt with Internet delivered interventions for depression, observed therapist-guided Internet cognitive behavioral therapy (ICBT) to be as effective as face–to-face psychotherapy, although there were no direct comparisons of effect sizes made across studies. A similar meta-analysis of 12 randomized trials of online interventions (which also included two computer-based studies) for depression observed a modest effect size (d = 0.41), with supported CBT having larger effect sizes than unsupported ones (Andersson & Cuijpers, Citation2009). There have been other reviews which have however been excluded since they focused on only computer-based CBT as opposed to Internet-based CBT or a combination of the two. Since most of the earlier reviews mentioned above were rigid in their definitions of the studies being included, several excellent studies remained excluded. This paper therefore systematically reviewed the existing research on online interventions for depression and anxiety disorders by expanding the scope of the search and including all studies on Internet-delivered interventions. It aimed to qualitatively as well as quantitatively review the efficacy of these interventions.
Method
Articles of potential relevance were identified using PsychInfo and PubMed to search a database of English language abstracts for articles published prior to January 2014. The search was carried out using the keywords “depression”, “anxiety”, “online”, “Internet”, “Web” and combinations thereof. The bibliographies of the articles identified via searches revealed additional sources. Studies were included only if they: (i) involved a self-help website intervention or an online intervention that incorporated a self-help component; (ii) described the website application as targeting a depression or anxiety condition; (iii) tested the efficacy or effectiveness of the intervention; (iv) incorporated a measure of symptom outcome for the targeted condition; and (v) had been peer reviewed and published. We specifically excluded computer-based CBT or tele-psychology, as these do not pertain to a direct online intervention. We also excluded studies, for which complete data were unavailable, which were not in English, or which did not primarily target depression/anxiety. Two independent reviewers reviewed all literature for available interventions and existing research, which was overseen by a senior professor independently. Within-group effect sizes were extracted from either the results section of the individual papers or from the data available using the RevMan 5.0 Meta-analysis calculator (Review Manager Citation5 (RevMan), Citation2011). Effect sizes were expressed as Cohen's d values.
Although not a primary aim, the methodological quality of the studies was additionally assessed using three basic criteria: (1) clients did not have prior knowledge of treatment assignment; (2) assessors of outcomes were blinded toward treatment assignment; and (3) complete follow-up data were available (Higgins & Green, Citation2005).
Results
The exhaustive search yielded more than 840 articles. Abstracts that did not have an online component, described only the program and not the effectiveness of the intervention, or were duplicates were rejected. A total of 43 publications met the inclusion criteria and which reported the results of trials for IBIs were included in . However, due to the variation in the methodologies of the studies reviewed, such as participant and control group characteristics, the type of intervention delivered, the differing durations of follow ups, it was not possible to compare effect sizes across studies. The studies were therefore systematically reviewed and grouped by treatment target into two categories and presented in : (a) depression and (b) anxiety disorders. For each, information is provided regarding sample characteristics, intervention conditions, sessions/modules, level of clinician involvement, follow-up periods, and within-group effect sizes.
Table 1. RCTs in depression with therapist guidance.
Table 2. RCTs in depression without therapist guidance.
Table 3. Non-RCT non-CBT interventions in depression.
Table 4. RCTs in anxiety disorders with therapist guidance.
Table 5. (a) RCTs in anxiety disorders without therapist guidance, (b) Non-RCT/non-CBT interventions for anxiety disorders.
Online interventions for depression
A total of 33 studies were selected, of which 26 involved the use of various CBT techniques including psycho-education, behavioral activation, cognitive restructuring, social skills training and relaxation, as well as problem solving and relapse prevention. Also, 29/33 studies were RCTs, with or without therapist guidance (which was defined as the presence of trained therapist involvement in the delivery of the intervention). The rest were either non-randomized studies that involved CBT or randomized studies that involved non-CBT techniques.
(a) RCTs ( and ): There were 29 RCTs involving online interventions for depressive disorders, this includes both with and without therapist guidance (Andersson et al., Citation2005; Andersson, Hesser, Veilord, et al., Citation2013; Bolier et al., Citation2013; Carlbring et al., Citation2013; Christensen et al., Citation2004; Clarke et al., Citation2009; Choi et al., Citation2012; De Graaf et al., Citation2009; Donker et al., Citation2013; Farrer, Christensen, Griffiths, & Mackinnon, Citation2011; Hollandare et al., Citation2011; Johansson et al., Citation2012, Citation2013; Kessler et al., Citation2009; Lintvedt et al., Citation2011; Meyer et al., Citation2009; O'Kearney et al., Citation2006; Perini, Titov, & Andrews, Citation2009; Ruwaard et al., Citation2009; Spek, Nyklicek et al., Citation2007; Spek et al., Citation2008; Titov, Andrews, Davies, et al., Citation2010; Ünlü Ince et al., Citation2013; Vernmark et al., Citation2010; Van Voorhees et al., Citation2009; Wagner, Horn, & Maercker, Citation2014; Warmerdam, Smit, van Straten, Riper, & Cuijpers, Citation2010; Warmerdam, van Straten, Twisk, Riper, & Cuijpers, Citation2008; van der Zanden, Kramer, Gerrits, & Cuijpers, Citation2012). These studies were studies from around the world; however Australia and Europe had major representation. Most studies involved the use of either the BDI or CES-D as assessment tools. Modules ranged from 6 to 12 weeks in length with follow-up periods ranging from 3 months to 5 years. Among the 29 RCTs, majority of the studies (19/29) were with the use of a therapist (Andersson, Hesser, Veilord, et al., Citation2013; Carlbring et al., Citation2013; Choi et al., Citation2012; Donker et al., Citation2013; Farrer et al., Citation2011; Hollandare et al., Citation2011; Johansson et al., Citation2012, Citation2013; Kessler et al., Citation2009; Perini et al., Citation2009; Ruwaard et al., Citation2009; Spek, Nyklicek et al., Citation2007; Titov, Andrews, Davies, et al. Citation2010; van der Zanden et al., Citation2012; Van Voorhees et al., Citation2009; Vernmark et al., Citation2010; Wagner et al., Citation2014; Warmerdam et al., Citation2008, Citation2010) while 10/29 did not use a therapist (Andersson et al., Citation2005; Bolier et al., Citation2013; Christensen et al., Citation2004; Clarke et al., Citation2009; De Graaf et al., Citation2009; Lintvedt et al., Citation2011; Meyer et al., Citation2009; O'Kearney et al., Citation2006; Spek et al., Citation2008; Ünlü Ince et al., Citation2013) and 2/29 compared therapist- to non-therapist guided CBT (Spek, Nyklicek et al., Citation2007; Vernmark et al., Citation2010). Therapist-guided CBT consistently had a larger effect size across all studies, ranging from 0.6 to 1.9, while stand-alone CBT (without therapist guidance) had a more modest effect sizes of 0.3–0.7. Almost all studies showed positive results with there being significant decrease in depression scores; however there were two contrasting results; one RCT where ICBT was found to be inferior to problem-solving therapy (Warmerdam et al., Citation2008) and the other RCT which did not find any differences between the wait-listed control and the intervention groups (Clarke et al., Citation2009). In addition, one study on economics-observed Internet-based CBT to be equal in costs (both direct and indirect) when compared to a wait-listed group (Warmerdam et al., Citation2010).
(b) Other interventions for depression (non-CBT/non-RCT) (): there were four studies in this section, with varying populations and techniques used (Lipman et al., Citation2011); (Andersson, Hesser, Hummerdal, Bergman Norgdren, & Carlbring, Citation2013; Mohr et al., Citation2010; Van Voorhees, Ellis, Stuart, Fogel, & Ford, Citation2005). All were open trials and one of these was among adolescents (Van Voorhees et al., Citation2005). However, modest to high effect sizes [0.2–1.7] were observed at the end of intervention in these studies too.
Online interventions for anxiety
There were 24 studies that met the inclusion criteria and evaluated Internet interventions for anxiety disorders. 18/24 studies again involved the use of various CBT techniques, including psycho-education, principles of CBT, cognitive restructuring, relaxation, exposure hierarchy and graded exposure, communication and assertiveness skills and relapse prevention. Under the broad rubric of anxiety disorders the following were represented: social anxiety disorders, generalized anxiety disorders (GADs), and mixed anxiety disorders. Panic disorders and phobias were not considered for this review since the nature of interventions differed largely from the other anxiety disorders. Also most studies (N = 18) were RCTs, with or without therapist guidance (Andrews, Davies, & Titov, Citation2011; Berger et al., Citation2011; Bolier et al., Citation2013; Carlbring et al., Citation2011; Carlbring, Nordgren, Furmark, & Andersson, Citation2009; Hedman, Andersson, Andersson, et al., Citation2011; Hedman, Andersson, Ljótsson, Andersson, Ruck, et al. Citation2011; Hedman et al., Citation2011a; Johansson et al., Citation2013; Johnston, Titov, Andrews, Spence, & Dear, Citation2011; Lorian, Titov, & Grisham Citation2012; Paxling et al. Citation2011; Robinson et al., Citation2010; Titov, Andrews, Choi, Schwencke, & Johnston, Citation2009; Titov, Andrews, Choi, Schwencke, & Johnston, Citation2009; Titov, Andrews, Choi, Schwencke, & Mahoney, Citation2008; Titov, Andrews, Johnston, Robinson, & Spence, Citation2010; Titov, Dear, Schwenke, et al., Citation2011). Among the other four studies, one was an open trial, one a follow-up study, and two others RCTs of a spiritually integrated treatment technique or a problem-solving intervention technique.
(a) RCTs ( and ): There were 19 RCTs with the majority involving therapist guidance (15/19) (Andrews et al., Citation2011; Berger et al., Citation2011; Carlbring et al., Citation2009, Citation2011; Hedman, Andersson, Andersson, et al., Citation2011; Hedman, Andersson, Ljótsson, Andersson, Ruck, et al. Citation2011; Hedman, Hedman, Andersson, Ljotsson, Andersson, Ruck, & Lindefors, Citation2011; Johansson et al., Citation2013, Citation2011; Paxling et al., Citation2011; Robinson et al., Citation2010; Titov et al., Citation2008, Citation2011 ; Titov, Andrews, Choi, Schwencke, & Johnston, Citation2009; Titov, Andrews, Johnston, Robinson, & Spence, Citation2010), three without therapist guidance (Bolier et al., Citation2013; Lorian et al., Citation2012; Titov, Andrews, Choi, Schwencke, & Johnston, Citation2009) and one compared therapist with non-therapist guidance) (Titov, Gibson, Andrews, & McEvoy, Citation2009). Since there were different anxiety disorders being reported, there was no single standard measure of scoring. Modules ranged from 6 to 12 weeks in length with follow-up periods ranging from 3 months to 5 years. Most studies on ICBT intervention in anxiety disorders have been on social anxiety, with a few on GAD or mixed groups. Most studies have also been therapist assisted with robust effect sizes of 0.7–1.7 observed with efficacy similar to face-to-face CBT. Stand-alone CBT studies also were observed to show large effect sizes (0.6–1.7). However, since there were only three non-therapist guided studies, it is difficult to compare them and such conclusions will await further research. All studies showed positive results, and no studies with contrasting results were reported. In addition, one study on the economics of ICBT intervention observed ICBT to be cheaper by about $2000 USD to conventional group-based cognitive therapy (CBGT) in both post-treatment and follow-up costs (Hedman et al., Citation2011a).
(b) Other interventions for anxiety disorders (non-CBT/non-RCT) (): There were only four studies in this category (Dear et al. Citation2011; Hedman, Furmark et al., Citation2011; Rosmarin, Pargament, Pirutinsky, & Mahoney, Citation2010; Ünlü Ince et al., Citation2013), with two being open trials of CBT in social anxiety (Dear et al. Citation2011; Hedman, Furmark et al., Citation2011) and the other being an RCT of a spiritually integrated treatment for subclinical anxiety (Rosmarin et al., Citation2010). Both studies observed significant reductions in anxiety scores at the end of the intervention.
Methodological quality of included studies
The quality of the included studies was reasonable to good. Prior knowledge of treatment assignment was presented in all studies. In most studies (>85%), outcome measures were self-reported by participants. Drop-out rates varied between 3% and 50%; hence follow-up data also varied.
Discussion
The findings of this review demonstrate that the Internet is an effective medium for the delivery of interventions designed to reduce the symptoms of depression and anxiety disorders. The effect sizes for both types of conditions were large or at least, modest. In fact, they were at least as large as standard psychological treatment (0.31) in primary care as reported in recent meta-analyses (Titov, Andrews, Choi, Schwencke, & Johnston, Citation2009). These effect sizes are comparable to the treatment of depression with antidepressant medication (0.37) (Robinson et al., Citation2010). Similarly, the effect sizes for anxiety interventions reported here are consistent with controlled effect sizes reported for standardized CBT for various anxiety disorders (Hedman et al., Citation2011c; Johnston et al., Citation2011; Titov, Andrews, Johnston, Robinson, & Spence, Citation2010). However, this comes with the caveat that these effect sizes are present regardless of the timing of follow-up assessments, which range from 3 to 36 months.
Most of the studies included here employed an intention-to-treat design. However, recruitment methods varied across studies, as did inclusion criteria. Some studies only included participants with a clinical diagnosis of a depressive or anxiety disorder, while others selected participants on the basis of a clinically significant cut-off score on a self-report measure or questionnaire. Others selected people with elevated but not necessarily clinically significant levels of symptoms, and one study employed a sample of participants with sub-threshold depression, specifically excluding those with a diagnosis of depressive disorder (van der Zanden et al., Citation2012). Among the studies included, some had assessed effectiveness of oral interventions in clinical samples with diagnosed psychiatric disorders, whereas others had used sub-threshold or only symptomatic diagnosis. A general trend of higher effect size was observed in the clinical, diagnosed samples while a moderate effect size was noted in the group having sub-threshold symptoms.
When it comes to interventions, there are wide variations in delivery as well as in components. Some programs are online versions of self-help manuals with limited or no interaction and others are based more on expert-driven structural frameworks (e.g. Deprexis) and artificial intelligence (AI), tailoring the process based on the experience of the process. When it comes to components of the interventions, there are again wide variations. The techniques that have been used in most depression studies were: cognitive restructuring (used in a total of 13 studies), behavioral activation (8 studies), and psycho-education and relapse prevention (6 studies). It is however important to note that some techniques are referred to differently but are similar to/or are part of, other strategies. For instance, “Thought Diary” and “Challenging Thoughts” are mentioned as individual techniques in one study, but since they are essential components of cognitive restructuring, they were likely used more than evidently shown. On the other hand, some strategies such as assertiveness skills training and sleep management have been used rarely.
With regard to studies about anxiety disorders, graded exposure was a reliable and often used strategy for different anxiety disorders and has been an essential component in 11 studies, while cognitive restructuring and relapse prevention were used in 10 studies each and psycho-education in nine studies, which reflects their importance for the intervention in both depression and anxiety disorders. Comparatively, techniques that were rarely used included self-confrontation and cognitive reappraisal.
In general, the techniques used were reliable and similar to clinical practice, yet some important techniques are used more in real-life CBT than in online interventions; relaxation, for example, has been used in only two studies, probably because it was implied in other techniques such as graded exposure. However, it forms an important component of conventional CBT for anxiety disorders and is one of the techniques used most often, in contrast to its rare use in online interventions. Such variations in the methodology make it impossible to compare across studies and evolve standards for assessment and intervention. Future research therefore needs to focus on effective and standard measures using interactive systems that effectively respond intelligently to the clients.
Based on the current available data, it is not possible to reliably draw conclusions about the factors that predict better outcomes. The effect sizes for anxiety trials appear larger than those for depression trials, but participants in the former trials were more often self-selected volunteers and were typically only included in the trial if they also satisfied diagnostic criteria at screening. There were also high drop-out rates, sometimes reaching 50%, with makes it difficult to comment on the actual effectiveness of the therapies. However, it can also be argued that this reflects treatment settings in the real world, with common drop-out rates reaching 50% in outpatient clinics.
Emerging evidence across trials, especially in depression, clearly suggests that IBIs aim not to replace human interaction, but could help to make much better use of extremely limited expert time. In fact, a direct correlation has been found between the amount of therapist contact in minutes and the between-group effect size (Lorian et al., Citation2012). However, the picture is not that clear for anxiety disorders, with two studies on CBT without therapist guidance observing near equal effect sizes as those with therapist guidance. Overall, Internet-based treatments are equally efficacious in generating a strong therapeutic alliance (Titov, Andrews, Choi, Schwencke, & Johnston, Citation2009), while not being strongly associated with outcome. Areas which need to be addressed in the future are the effects of Internet-based treatment related to age and gender, the mechanisms of action and the appropriateness of psychosocial techniques for the online treatment. In addition, it is also essential to explore how these interventions can be integrated into a system of knowledge exchange and assessment strategy.
One of the strengths of this review, which attempted to systematically review the efficacy of online interventions for depression and anxiety, has been the use of original data and outcomes, which allow more clarity and intuitive reading. We believe that transformation of data or outcomes, although important, can sometimes make the review complicated to understand, and we have tried to keep it simple and informative to the reader. In addition, this review has been very exhaustive yet specific, in that it has targeted an understanding of all interventions for anxiety and depression delivered over the Internet. However, the findings of this review have to be understood in light of certain limitations. Despite our broad search, it may be possible that certain good studies may not have been included or been overlooked, due to the search criteria. Also, the desire to be very inclusive may have diluted actual effect sizes or precluded some useful comparisons. Since there were significant differences in study groups, type of interventions and study periods, it was difficult to generate a standardized mean difference (SMD) using pooled data analysis, making any definitive conclusion impossible. Also, we found no trials involving rural residents, older people, or people with low levels of education, which is another limitation of this review. Although we also attempted to analyze the cost-effectiveness of online interventions, the lack of studies prevented us from doing any comprehensive analysis.
Conclusion
This review documented that the identified programs were successfully delivered in a variety of settings, with differing levels of professional support. This finding highlights the versatility of Internet-based programs and that only brief professional support, if any, is necessary in their delivery. We are led to believe that future interventions would include all groups, especially the rural and the elderly, who would likely also benefit from online interventions.
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