Effectiveness of Art Therapy With Adult Clients in 2018—What Progress Has Been Made?

In the year 2000, an important art therapy literature review addressed an essential question—does art therapy work? It discussed 17 articles dealing with the issue of the effectiveness of art therapy. Two decades later, this research field has extended its scope and is flourishing. Several current reviews of research work have described the broad range of methods implemented today, which includes qualitative and quantitative studies; other reviews have focused on art therapy with specific populations, or by age group. The aim of this systematic literature review is to contribute to the ongoing discussion in the field by exploring the latest studies dealing with the effectiveness of art therapy with a broad scope of adult clients. We conducted a comprehensive search in four databases and review of every quantitative article that has addressed outcome measures in the art therapy field from 2000 to 2017. This paper presents the latest 27 studies in the field that examine the effectiveness of art therapy with adult clients and divides them into seven clinical categories: cancer patients, clients coping with a variety of medical conditions, mental health clients, clients coping with trauma, prison inmates, the elderly, and clients who have not been diagnosed with specific issues but face ongoing daily challenges. It underscores the potential effects of art therapy on these seven clinical populations, and recommends the necessary expansions for future research in the field, to enable art therapy research to take further strides forward.

In the year 2000, an important art therapy literature review addressed an essential question-does art therapy work? It discussed 17 articles dealing with the issue of the effectiveness of art therapy. Two decades later, this research field has extended its scope and is flourishing. Several current reviews of research work have described the broad range of methods implemented today, which includes qualitative and quantitative studies; other reviews have focused on art therapy with specific populations, or by age group. The aim of this systematic literature review is to contribute to the ongoing discussion in the field by exploring the latest studies dealing with the effectiveness of art therapy with a broad scope of adult clients. We conducted a comprehensive search in four databases and review of every quantitative article that has addressed outcome measures in the art therapy field from 2000 to 2017. This paper presents the latest 27 studies in the field that examine the effectiveness of art therapy with adult clients and divides them into seven clinical categories: cancer patients, clients coping with a variety of medical conditions, mental health clients, clients coping with trauma, prison inmates, the elderly, and clients who have not been diagnosed with specific issues but face ongoing daily challenges. It underscores the potential effects of art therapy on these seven clinical populations, and recommends the necessary expansions for future research in the field, to enable art therapy research to take further strides forward.
Keywords: art therapy, effectiveness evaluation, adult, systematic review, clinical populations In 1999, nearly two decades ago, the American Art Therapy Association (AATA) (1999) issued a mission statement that outlined the organization's commitment to research, defined the preferential topics for this research, and suggested future research directions in the field. One year later, Reynolds et al. (2000) published a review of studies that addressed the therapeutic effectiveness of art therapy. They included studies that differed in terms of research quality and standards. In eight studies by different authors, there was a single group with no control group; in four studies, there was a control group, but no randomization of the participants between the experimental group and the control group; and in only five studies was there randomization of the experimental group and the control group (RCT -Randomized Control Trial). They concluded that there was a substantial need to expand research in the field of art therapy to better determine the most appropriate interventions for different populations.
Two decades later, the field of research in art therapy has developed considerably. There are several reviews in the field that describe the expanding body of research work. Some of these reviews present studies that have examined the effectiveness of art therapy, without distinguishing between different populations. For example, as an extension of the work and review by Reynolds et al. (2000), Slayton et al. (2010) reviewed articles published between 1999 and 2007 that measured the outcome of art therapy sessions with different populations. Their review included qualitative studies, studies based on a single client in therapy, studies with no control groups, studies with a control group but with no randomization, and a small number of studies with a control group and randomization. They concluded that there has been progress in the field, but further research is needed. Four years later, Maujean et al. (2014) summarized high-quality studies that implemented RCT that focused on art therapy with adults. They found eight such studies that were conducted between 2008 and 2013. Seven reported beneficial effects of art therapy for adult clients, but they also concluded that more reliable controlled studies were needed to draw conclusions.
Together with these comprehensive reviews, many literature reviews have appeared in recent years discussing specific populations and a range of research methods. For example, in the field of art therapy for adults, Holmqvist and Persson (2012) overviewed art therapy studies on clients with psychosomatic disorders, eating disorders, or facing crises, based on case studies and intervention techniques. They concluded that there were not enough studies to prove that art therapy is effective for these specific disorders. Similarly, Geue et al. (2010) and a year later, Wood et al. (2011) examined art therapy with cancer patients. They assessed quantitative and qualitative studies and found that most studies have dealt with women suffering from breast cancer. They also documented the intervention techniques that were specifically used with this population, and reported that overall, the quantitative studies reported an improvement in a number of emotional domains faced by these clients. Another article by Huet (2015) reviewed articles dealing with ways to reduce stress in the workplace through art therapy intervention techniques. In this article, a total of 11 articles were discussed that employed different research methods. The authors focused on describing different ways to use art therapy in this context and argued that there has been a gradual emergence of a vast body of knowledge that reinforces the benefits of art therapy for people working in stressful work environments.
In the past three years, a number of literature reviews of controlled quantitative studies have dealt more specifically with the issue of the effectiveness of art therapy in treating specific populations. Schouten et al. (2015) overviewed quantitative studies in art therapy with adult trauma victims. They found that only six studies included a control group (only one of which included randomization) in this field. Half reported a significant reduction in trauma symptoms and another study found a decrease in the levels of depression in clients treated with art therapy. They pointed out that it is difficult to produce quantitative meta-analyses in art therapy given the limited size of the groups and because the evaluation is often based on several therapeutic methods that are used simultaneously. Further Uttley et al. (2015a,b) reviewed all the studies dealing with art therapy for adult clients with non-psychotic psychiatric disorders (anxiety, depression, and phobias). They found 15 randomized controlled quantitative studies of which 10 indicated that the therapeutic process was effective (positive changes following therapy in comparison to the control group). They were unable to conduct a meta-analysis due to the clinical heterogeneity and lack of sufficient information in the studies. In addition, they reviewed 12 qualitative studies that provided data on 188 clients and 16 therapists.
This article deals with research that focuses on measuring the effectiveness of art therapy. It addresses two major challenges. The first is the definition of the term "effectiveness." We adopted the definition suggested in Hill et al. (1979); namely, "the attribute of an intervention or maneuver that results in more good than harm to those to whom it is offered" (p. 1203). The current review takes a positivist perspective (Holton, 1993) and relates to the measurement of effectiveness reported in quantitative studies that have been conducted in the field. Since the field of art therapy is still young, the scope of research is limited and the quality of research is diverse, which makes it difficult to create a comparative review that presents the knowledge in the field and draws thorough conclusions. Therefore, our review is based on the systematic review framework proposed in Case-Smith (2013) who divided the studies she reviewed into three levels of evidence. Level 1 refers to randomized controlled trials (RCT's), level 2 refers to nonrandomized two-group studies, and level 3 refers to nonrandomized one-group studies.
The second challenge has to do with the definition art therapy. We applied the standard definition provided by the American Art Therapy Association: Art therapy, facilitated by a professional art therapist, effectively supports personal and relational treatment goals, as well as community concerns. Art therapy is used to improve cognitive and sensorimotor functions, foster selfesteem and self-awareness, cultivate emotional resilience, promote insight, enhance social skills, reduce and resolve conflicts and distress, and advance societal and ecological change (American Art Therapy Association, 2018).
This definition makes it clear that art therapy is a process that takes place in the presence of a certified art therapist, and indicates different areas where an effect or outcome in therapy can be expected as a result of this form of treatment.
Thus, the research question was formulated according to "PICOS" components (The PRISMA Group et al., 2009): Is art therapy effective for adult clients as measured in results published from 2000 to 2017, in various quantitative studies corresponding to Levels 1, 2, 3 (Case-Smith, 2013)? These studies assessed the effectiveness of art therapy on variety of indices including symptoms and physical measures, health or mental health assessments, quality of life assessment, or coping resources. These indices were typically evaluated through questionnaires and occasionally by projective drawings or physiological indices.
By posing this question, this systematic review joins the ongoing discussion in the field on the level of effectiveness of art therapy with adult clients. This forms part of the academization process in the field of art therapy, which involves attempting to relate intervention techniques in the field with their significance for theoretical research.

METHOD
The search for relevant articles was carried out during the month of January 2017. Four major electronic databases were searched: Medline, PsycInfo, Scopus, and Web of Science. We searched for the term "art therapy" in the databases combined with the terms "Effectiveness, " "Efficacy, " "Outcome, " "Measurement, " "Treatment, " and "Intervention." We restricted the search in the databases to articles published in English since the year 2000 for reasons of recency and the continued relevancy of the findings. In addition, all the literature reviews in the field (such as those reviewed above) were examined to locate additional articles that were pertinent to this study.
During the initial screening stage, the abstracts were read by both authors (who are certified art therapists) to exclude those that were irrelevant to the purposes of the study. At this point 151 articles remained (see Figure 1).
In the next stage, the remaining articles were read and selected if they met the following inclusion criteria (see Figure 1): -Reported a quantitative assessment of the effectiveness of art therapy on a sample of clients. Hence case studies, method descriptions, qualitative analyses, and literature reviews that did not meet these criteria were omitted. A total of 80 articles were removed at this stage. -Enabled the assessment of the unique impact of art therapy. We thus omitted articles that described the use of a combination of therapeutic intervention techniques with a variety of art mediums simultaneously, not only visual art. A total of 14 articles were omitted at this stage. -The art therapy was conducted in an ongoing manner in the presence of a certified art therapist. We thus omitted articles that described art intervention techniques that were not used in the context of therapy or were used in one-off art therapy interventions or therapy sessions with a non-certified art therapist. A total of 17 articles were removed at this stage.
Articles that met these inclusion criteria were defined as articles that examined the "effectiveness" of Art Therapy, and that quantified the impact of art therapy in a measurable way. A total of 37 studies were located in 40 articles (three studies were published in two different articles each). Of the 40 articles, 27 dealt with adult populations and are covered in this systematic review. This article categorizes mentioned articles in terms of the levels of evidence proposed by Case-Smith (2013).

FINDINGS
The findings derive from the 27 studies that we considered to have met the inclusion criteria. The choice to present the studies as a review rather than as a meta-analysis is due to the emergent nature of the field of art therapy. There is insufficient research in the field and the differences between studies and the indices measured are so great that it was impossible to produce a metaanalysis that would yield meaningful results (much like Uttley et al.'s conclusion, 2015a,b). In addition, the authors discussed the issue of the clinical categorization until full agreement was reached, to enable the reader to access the knowledge in the field in a way that will allow and encourage researchers to continue to conduct research. For samples where there has been more research (for example, art therapy with cancer patients), this area could have been separate and examined in and of itself, and relevant conclusions specific to this population could have been drawn. However, for other populations there was often a scarcity of studies which led us to group and categorize populations with similar characteristics (for example, medical conditions). The next section presents the findings categorized into seven clinical categories. Different research methods were used: 17 of the articles (15 studies) used a comparison group with randomization (Level 1), five articles (four studies) used a comparison group without randomization (Level 2), and five articles used a single group without a comparison group (Level 3). In addition, there was a notable gender trend in that nine of the articles only examined women whereas only two of the articles exclusively referred to men. Sixteen did not define the research population by gender.

Category 1: Cancer Patients
The first category consisted of art therapy with cancer patients (see Table 1). Six studies that examined effectiveness have been conducted with this specific population since 2006 and have been described in seven different articles (Monti et al., 2006(Monti et al., , 2012Oster et al., 2006;Öster et al., 2007;Bar-Sela et al., 2007;Svensk et al., 2009;Thyme et al., 2009). Five of the six studies were randomized (Level 1) and five dealt with women, most of whom had breast cancer. The total sample size ranged from 18 to 111 clients, most of whom were treated individually. Most of the therapeutic processes were short-term and ranged from five to eight sessions. Some of the studies utilized different streams of art therapy. For example, the largest study of 111 participants, (Monti et al., 2006) included a mindfulness-based art therapy interventiona combination of art therapy with mindfulness exercises. The measurement indices were very different for these studies and included questionnaires that examined physical symptoms, coping resources, quality of life, depression, anxiety, and fatigue. One specific study (Monti et al., 2012) also dealt with fMRI measurements. The findings of this category suggest that through relatively short-term interventions in art therapy (primarily individual therapy), it is possible to significantly improve the emotional state and perceived symptoms of these clients.

Category 2: Medical Conditions
The second category consisted of art therapy with clients coping with a variety of medical conditions that were not cancer-related (see Table 2). Three studies examining the effectiveness of art therapy have been conducted since 2011, each of which deals with a completely different medical condition and employs a different research method. The earliest study dealt with art therapy with clients with advanced heart failure (Sela et al., 2011). This study had a sample size of 20 clients who were randomly divided into two groups (level 1). The clients participated in group art therapy for 6 weeks. A 2013 study addressed art therapy with clients coping with obesity (Sudres et al., 2013). This study examined 170 clients who were randomly divided into two groups (level 1).

FIGURE 1 | Search process.
One group consisted of 96 clients who received art therapy for 2 weeks. A 2014 study addressed art therapy with 25 clients with HIV/AIDS (Feldman et al., 2014), who received art therapy in individual or group settings and did not include control groups (level 3). The duration of the therapeutic process was one or more sessions. Despite the considerable differences between the Frontiers in Psychology | www.frontiersin.org populations and the indices measured, these preliminary studies present an introductory description that points to the potential of art therapy to assist these populations.

Category 3: Mental Health
The third category covered art therapy with mental health clients (see Table 3). Four studies have been conducted since 2007 (two articles written on the same study- Crawford et al., 2012;Leurent et al., 2014, see Table 3). Research in this category falls into two main diagnostic areas. The first covers two studies on individuals with schizophrenia (Richardson et al., 2007;Crawford et al., 2012;Leurent et al., 2014) that involved randomization (level 1) with large samples (90-159 clients). The therapeutic process ranged from 12 sessions to a full year of therapy and included group therapy. The variety of indices that were used in these studies include measures of function, relationships and symptoms. Despite the attempt to use different types of research indices, in both studies, little or no effect was found to be associated with art therapy. Two studies were classified into the second diagnostic area: one addressing clients with psychiatric symptoms (Chandraiah et al., 2012) (level 3) and the other addressing women coping with depression  (level 1). The therapeutic process ranged from 8 to 15 weeks. The findings reported in both studies suggested a change occurred in the duration of the therapeutic process. However, since neither study compared clients who received art therapy with those who received no therapy, it is difficult to evaluate the effectiveness of art therapy. Hence, the accumulated results of the studies in this category suggest that further research is needed to assess the effectiveness of interventions in art therapy for clients dealing with mental health issues.

Category 4: Trauma Victims
The fourth category included art therapy with clients coping with trauma (see Table 4). In this category, two studies have been conducted since 2004, both with randomization (level 1). The first study (Pizarro, 2004) was composed of a sample of 45 students who participated in two art therapy sessions. These students had dealt with a traumatic event, which could occur at different levels of intensity and at various stages in their lives. In addition, the comparison was made between an art-therapy group and two comparison groups where one underwent writing therapy and the other experimented with artwork, regardless of the traumatic event. Despite the attempt to use a wide range of indices, including symptom reporting and emotional and health assessments, and perhaps because of the short duration of therapy, this study failed to find significant results.
The second study (Kopytin and Lebedev, 2013) examined a sample of 112 war veterans who participated in 12-14 art therapy sessions. In this study, in which the definition of the traumatic event was more specific and defined by involvement in war, an attempt was also made to measure the level of improvement through a wide range of research indices, including reports of symptoms, emotional state, and quality of life. For some of the indices, there was a significant improvement compared to the control group.
These two articles thus present an inconsistent picture of the beneficial effects of this intervention, which may depend on the indices measured, the duration of therapy, and possibly the type of traumatic event.

Category 5: Prison Inmates
The fifth category deals exclusively with David Gussak's extensive research on art therapy with prison inmates (Gussak, 2004(Gussak, , 2006(Gussak, , 2009a) (see Table 5). In this area three effectiveness studies have been conducted since 2004 (two articles were written on the same study; see Table 5). The first examined an intervention group without a control group (level 3), in contrast to the other two studies which did include control groups (level 2); the sample sizes ranged from 48 to 247 participants in the 2009 study. The art therapy intervention was carried out in a group setting and lasted 4 weeks in the first study to 15 weeks in the most recent study. Initially, Gussak used measurements solely from drawings (FEATS), but in later and more comprehensive research, depression and locus of control were also assessed. In the three studies, there was a reported improvement attributed to the art therapy intervention, as seen in the emotional state of the prison inmates.

Category 6: The Elderly
The sixth category covered art therapy with the elderly (see Table 6). Three effectiveness studies have been conducted since 2006: one study was conducted with healthy Korean American older individuals (Kim, 2013), the second study involved older individuals coping with depression (McCaffrey et al., 2011), and the third dealt with older individuals with moderate to severe dementia (Rusted et al., 2006). In all three studies, the participants were randomly divided into groups (level 1), in a group therapy setting, with a sample size of 39-50 clients. The number of sessions ranged from 6 to 40. The authors of these studies were interested in a variety of indices. In both the study of elderly Koreans and the elderly coping with depression, various aspects of the emotional state of the clients were measured. Art therapy was considered to have led to an improvement on these measures. In a study of older people with dementia, many observational measures were used to assess emotional states, behavior, and abilities, but change was found only in some of them.
The findings suggest that art therapy seems to have a beneficial effect on older individuals who are coping with a variety of challenges in their lives, as reflected in the changes in the indices in these studies.

Category 7: Clients Who Face Ongoing Daily Challenges
The seventh category consisted of art therapy with clients who face ongoing daily challenges that do not fall into one diagnostic category (see Table 7). Three studies have been conducted since 2008, two of which address issues such as stress, distress, and burnout of individuals working in various health professions (Italia et al., 2008;Visnola et al., 2010). These studies were carried out without randomization; in one study (Visnola et al., 2010) there was a control group (level 2), whereas in the other (Italia   From two adult day health care programs (ADHCP) The structure of the art therapy intervention was based on the psycho-cybernetics approach to art therapy (Nucho, 2003 al., 2008) there was not (level 3). The sample size ranged from 20 to 60 participants. The therapeutic process lasted 9-13 sessions in a group art therapy setting. These studies suggest that art therapy can help healthcare professionals reduce levels of stress, anxiety, and burnout connected to their work. The third article addresses art therapy for women undergoing fertility treatment (Hughes and da Silva, 2011). The sample only included an intervention group (level 3) consisting of 21 women in a group art therapy setting. This study reported a reduction in anxiety and in feelings of hopelessness. The samples in the studies in this category were relatively small and usually did not include a control group. However, there is potential for further research in this area.

DISCUSSION AND CONCLUSION
The purpose of this review was to assess whether art therapy is effective for adult clients as measured in quantitative studies published from 2000 to 2017. Notably, since the Reynolds et al. (2000) review, the body of knowledge in this field has grown and established itself significantly, and a growing number of RCT studies (level 1) have been conducted with larger sample sizes. The advantage of such studies lies in the lesser likelihood of Type I errors as opposed to other studies with no control group or studies that have a control group but no randomization. Nevertheless, there are still only a small number of studies addressing each population, and these studies differ considerably in terms of the course of the therapeutic process, the proposed interventions and the indices that were examined, hence making a meaningful meta-analysis impossible. The findings however are largely encouraging and show a growing trend toward conducting more carefully designed studies that lend themselves to validation and replication; yet-there is a long road ahead. In the past, the effectiveness of art therapy was noticeable to those involved in the field, but less to other professionals. Today, by contrast, there are impressive published findings in a variety of areas. These studies can help expand the contribution of art therapists in other areas and with other populations.
During our search, we were struck by the large number of articles which appear to present interventions in the field of art therapy, but in fact were conducted by non-certified art therapists or were restricted to a therapeutic intervention of a single session in a manner that would not be considered therapy. The existence of such studies emphasizes the continued need to define, clarify and specify what art therapy is and what it is not, and specifically to clarify that this type of therapy must be composed of ongoing sessions and be conducted by a certified art therapist who meets the criteria defined for the profession (American Art Therapy Association, 2018).
The first two clinical categories dealt with clients who are coping with a variety of medical conditions. In this section, we were surprised by the vast amount of research in the field of art therapy with cancer patients, most of which were categorized as level 1. Art therapy emerges strongly as a way to enhance their quality of life and their ability to cope with a variety of psychological symptoms. Our review supplements previous Level 3 Frontiers in Psychology | www.frontiersin.org reviews in the field (Geue et al., 2010;Wood et al., 2011) and shows that the findings on art therapy with cancer patients are primarily based on higher levels of evidence studies with randomization and relatively large samples. The second category, which dealt with clients with a range of medical problems, was intended primarily to list the preliminary research in this field, due to the wide variability between the different populations. The differences in the populations treated suggests that, the measurement tools should be adapted to each type of medical issue. The only instrument that could possibly be applied to all these populations in future research is one that measures improvement in quality of life. It is surprising to note that unlike research on cancer patients, which has been considerable, there have been few studies on individuals with other medical conditions.
The third category dealt with clients with mental health issues. In this category we focused solely on adult clients (as opposed to children which will be reviewed in a separate article) and differentiated from the elderly (category 6). In addition, they were separated from clients coping with trauma (category 4). As a result, a relatively small number of studies met the strict criteria of this review regarding what could be defined as art therapy for clients with mental health issues, although some of the studies had large sample sizes and showed a higher level of evidence. For clients coping with schizophrenia, the reviewed findings are not optimistic. These data are congruent with the many articles on psychotherapy that have addressed this population and have emphasized the complexity of treating such individuals (Pfammatter et al., 2006). Studies have shown that the most effective therapeutic approach for this population appears to be cognitive-behavioral (Turner et al., 2014). Thus, future work should examine the effectiveness of the cognitivebehavioral approach in art therapy for this population. More research is also needed to better understand how art therapy can be effective with clients experiencing other mental health issues.
The fourth category addressed clients coping with trauma. While there have been few studies in this field, all of them are in a higher level of evidence. It is important to note that these studies did not assess post-traumatic stress disorder (PTSD), but rather individuals who have dealt with traumatic events. Even though the first study (Pizarro, 2004) did not confirm the effectiveness of art therapy, the limited number of sessions with each client may have been a major factor. When dealing with trauma, there is a need for thorough processing of the experience, and it is quite possible that two sessions were insufficient. The second study (Kopytin and Lebedev, 2013) reported that art therapy was beneficial when the intervention lasted longer. These data are consistent with the Schouten et al. (2015) review. Certain studies reviewed by Schouten et al. (2015) were not mentioned in our review because some were not published as articles, and others included single session interventions that were not led by a certified art therapist.
The fifth category addressed prison inmates. In this field, it is worth mentioning the work of Gussak, a researcher who has studied the field and conducted several studies with an increasing number of participants. His findings undoubtedly point to the potential of art therapy for inmates particularly in long term interventions.
The sixth category addressed the elderly. The field of geriatric art therapy has been gaining momentum in recent years (Im and Lee, 2014;Wang and Li, 2016). It is clear from the articles that group therapy sessions are particularly suitable for these clients and that it is important to continue conducting research to target effective intervention methods for this population. The research findings certainly indicate the potential of this field.
The seventh and final category dealt with clients who are facing daily challenges in their lives. The findings suggest that art therapy can be a suitable form of treatment and a way to mitigate issues such as stress and burnout at work.
Overall, this review documents the extensive research conducted in recent years; although qualitative studies were not included in this article, there is no doubt that using a variety of research methods can help expand knowledge in the field. As concerns quantitative studies, the review examined the effectiveness of art therapy for adult clients from research in the field from recent years and with reference to seven clinical categories.
The current review has several limitations. First, due to the small number of studies in the field, it includes various levels of quantitative studies. Some lack comparison groups and others include comparison groups with other treatment methods (for example verbal therapy). This variability makes it difficult to generalize across findings, but not mentioning these studies would have led to the inclusion of an even smaller number of studies. Second, in many studies there are several indices of varying types (questionnaires, drawings, physiological indices). Occasionally, only some of these indices led to demonstrable indications of the effectiveness of art therapy. Due to the complexity of the findings, we were not always able to detail these subtleties and challenges in the current review, and future researchers interested in the field should examine these specific studies closely before conducting further research on the same population. In addition, due to the limited number of studies in this field, we needed to combine various subjects in certain cases, make decisions, and create artificial categories based on our professional knowledge and judgment. For example, the article on female infertility (Hughes and da Silva, 2011) was placed in the seventh category of ongoing and daily challenges, and not in the second category of medical problems, due to the feasibility of this condition for various reasons, which are not necessarily medical.
Research in the field can be expanded in several ways. First, art therapy is a very broad domain that covers diverse populations, some of which have not yet been studied at all in the context of treatment effectiveness. Second, based on the conclusions derived from this review future studies should be planned so that they are performed by a certified art therapist, over a continuous period of time and on large enough samples. In so doing, within approximately a decade, it should be possible to produce a meaningful meta-analysis based on significant and comparable findings from the field, which could lead to more advanced and specific conclusions. Third, in order to raise the level of research in our field, it is important for researchers to devote time and thought to planning studies at the highest level (level 1). Large samples are not enough; one should also consider well-controlled studies (RCT), the blindness of the experiment, the blindness of the participants and the experimenters to the purpose of the research, the division of research groups and so on (Liebherz et al., 2016;Munder and Barth, 2018). Finally, it is of great importance that researchers will select valid and reliable research tools that have been used extensively. This documentation of the numerous studies on the effectiveness of art therapy was long and complex, but also filled us with hope. We are optimistic that this article will take the field one step further in this direction.