Background Athletes, like non-athletes, suffer from mental health symptoms and disorders that affect their lives and their performance. Psychotherapy, either as the sole treatment or combined with other non-pharmacological and pharmacological strategies, is a pivotal component of management of mental health symptoms and disorders in elite athletes. Psychotherapy takes the form of individual, couples/family or group therapy and should address athlete-specific issues while being embraced as normative by athletes and their core stakeholders.
Main findings This narrative review summarises controlled and non-controlled research on psychotherapy for elite athletes with mental health symptoms and disorders. In summary, treatment is similar to that of non-athletes—although with attention to issues that are athlete-specific. Challenges associated with psychotherapy with elite athletes are discussed, including diagnostic issues, deterrents to help-seeking and expectations about services. We describe certain personality characteristics sometimes associated with elite athletes, including narcissism and aggression, which could make psychotherapy with this population more challenging. The literature regarding psychotherapeutic interventions in elite athletes is sparse and largely anecdotal.
- elite performance
- sport psychology
Statistics from Altmetric.com
In 2013, one of the first articles on psychotherapeutic management of elite athletes with mental health symptoms and disorders was written.1 Since then, there has been an increased focus on these issues, although very little controlled research. This narrative review summarises that literature.
Psychotherapy is defined as the treatment of mental health symptoms or disorders or problems of living and/or facilitation of personal growth, by psychological means; it is often based on therapeutic principles, structure and techniques. Providers who are qualified to provide psychotherapy include clinical psychologists and psychiatrists, and in most areas, licensed mental health counsellors, licensed professional counsellors, licensed clinical social workers and licensed marriage and family therapists.2 The goal of this review is not to address or summarise literature on psychological performance enhancement techniques, but rather to address psychotherapy as a treatment intervention for elite athletes who have mental health symptoms and disorders.
We searched five electronic databases (PubMed (MEDLINE), SportDiscus via EBSCO, PSycINFO via ProQuest, Scopus and Cochrane) from inception to November 2018. Search terms relating to mental health disorders, sports participation, the elite nature of participation and psychotherapy were combined. To retrieve relevant articles, inclusion criteria were: (1) the study population consists exclusively of current or former elite athletes and (2) the article is written in English. To avoid missing any relevant publications, references of the included studies were screened. Other literature was also reviewed, including that related to psychotherapy with general populations or with non-elite athletes, where there were gaps in elite athlete-specific literature. Elite athletes were defined as those competing at professional, Olympic or collegiate/university levels.
Mental health symptoms and disorders as a target for psychotherapy
The intense demands placed on elite athletes are a critical aspect of a sporting career, and these demands may increase an elite athlete’s susceptibility to certain mental health symptoms and disorders and risk-taking behaviours.3 Mental health symptoms and disorders in elite level athletes have received increased attention in recent years. Elite athletes are exposed to sport-specific stressors, including competitive factors (eg, performance expectations), organisational factors (eg, travel) and personal issues (eg, family), that potentially increase their risk for mental health symptoms or disorders, including anxiety, depression, eating disorders or substance abuse issues.4 Likewise, factors that are common in elite athletes such as excessive training coupled with inadequate recovery, career termination from injury or inadequate performance and retirement may increase vulnerability to mental health symptoms and disorders.4 In this context, Gouttebarge et al found that the number of severe musculoskeletal injuries and surgeries during an athlete’s sport career were positively correlated with self-reported symptoms of ‘distress, sleep disorders, adverse alcohol behaviour and adverse nutritional behaviours’ among male European professional football players.5
Just under half of respondents in an elite athlete sample met criteria for at least one mental health ‘problem’.6 These included general psychological distress, depression, generalised anxiety, depression, social anxiety, panic disorder or eating disorders. In a study by Gulliver et al, approximately one-quarter of elite athletes scored above the cut-off score for ‘depression’, suggesting a possible depressive disorder.6 Similarly, Foskett and Longstaff found that nearly half (47.8%) of the elite athletes showed symptoms of ‘anxiety/depression’ and just over a quarter (26.8%) showed signs of ‘distress’.7 They also found between 26% and 37% of athletes had some combination of anxiety, depression and distress.7 A study of Australian elite athletes asked to self-report symptoms demonstrated that 14.7% met criteria for social anxiety, 7.1% for generalised anxiety disorder and 4.5% for panic disorder.6 Approximately one-tenth of male respondents and one-third of female respondents in the same study met criteria for an eating disorder.6
Substance use disorders—especially those involving alcohol—are common among athletes.8 Despite some studies that suggest participation in sport can protect against substance use, binge drinking is more common in college athletes than non-athletes.8 As in the general population, alcohol is the most commonly overused substance among athletes.9 Likewise, Rice et al found that studies related to alcohol use indicated higher rates of consumption in athletes relative to the general community.10 This may be largely due to a binge pattern of consumption during non-competitive or vacation periods.10 Cannabis is also used in athletic populations and is associated with factors such as high sensation-seeking tendencies and overestimating the normative use of the substance.8 Seitz et al found that athletes are more likely to use cannabis recreationally compared with non-athletes.11 Approximately 5% of elite athletes also use tobacco; rates vary depending on age and sex.12 Finally, Elbe and Pitsch found that in a survey of elite Danish athletes, 30.6% admitted to ‘doping’, (defined as the use of banned athletic performance-enhancing drugs by athletic competitors) with a lifetime prevalence between 3.1% and 26%.13
In sum, existing evidence demonstrates that athletes experience numerous stressors and appear to commonly suffer from mental health symptoms and disorders. All of these are potential targets for psychotherapeutic interventions.
Evaluation and diagnosis
When an elite athlete presents for mental health evaluation, the provider must make a formulation (detailed understanding of the biological, psychological and social factors contributing to symptom presentation) of the case, including assessing: (1) individual factors; (2) family systems factors and (3) a diagnosis based on the Diagnostic and Statistical Manual of Mental Disorders, fifth Edition (DSM-5).14 15
One challenge is convincing elite athletes to seek help when they develop mental health symptoms or disorders, as denial of psychological problems is common among successful athletes.16 A related problem is the stigma of receiving mental health services.17 Athletes are less likely to seek help for mental health symptoms and disorders and have fewer positive attitudes towards mental health services than the general population.18 One of the biggest deterrents of seeking treatment is fear of not being allowed to participate in sport.19 In many sports ‘mental toughness’ is lauded, and the idea of receiving care for mental health may seem ‘weak’. As such, going to a mental health professional is commonly viewed as evidence of being ‘crazy’ or untrustworthy.16 These factors, coupled with a sense of invincibility and/or a lack of thinking about or planning for the future, create major barriers for elite athletes to start psychotherapy.17
Because of these barriers, psychoeducation delivered to athletes, and any core stakeholders of the athlete entourage, is useful in these situations to explain the need for and potential benefits of psychotherapy for athletes who suffer with mental health symptoms and disorders.16 Psychoeducation is defined as an intervention that provides information, educational materials and/or feedback/advice to individuals with mental health symptoms or disorders or other medical illnesses.20 Results from meta-analyses of psychoeducational interventions have shown significant effects on symptom reduction for depression and psychological distress.20 Psychoeducation can be applied immediately, offers a first-step intervention for those experiencing mental health symptoms or disorders and is the cornerstone of all psychotherapeutic intervention.20
Given the athlete’s probable reluctance to engage in psychotherapy, the clinician may need to reframe such treatment as ‘performance help’ to encourage participation in the therapeutic process.16 In addition to such reframing, other common facilitators of psychotherapy include social support, encouragement from others to do so, positive relationship with service staff, confidentiality, time for therapy sessions, integration into athlete life and positive past experiences with help-seeking.21
Often, those who form an athlete’s support system can be helpful in providing information that may not be otherwise disclosed by an athlete in an initial visit. These individuals include coaches, team physicians, trainers, teammates and especially family members—each of whom can provide a more comprehensive perspective of the athlete and their problems.8 After obtaining the athlete’s consent for sharing any information with others, it may be helpful to include these significant others when conducting the initial clinical evaluation and formulating an understanding of the case.1
Because coaches and other core stakeholders are interested in services that improve player performance, they may be more willing to recommend that athletes seek help than athletes themselves are to seek it22 and may have insight into athlete-specific barriers such as stress, insomnia, performance anxiety, inattention and impaired learning. A multidisciplinary intervention can lead to increased use of mental strategies in practice and competition to address such barriers.22 Family members and significant others may want to be included in treatment strategies, as they are a normal component of the athlete’s day-to-day life.8 Sometimes non-family individuals close to the athlete, such as coaches or agents, may want to be included in treatment. In fact, it is common for elite athletes to have an entourage of helpers, and any role of these helpers in psychotherapy may be complex. For example, a coach may be the one who initially encourages the athlete to begin medication for mental health symptoms, but then might suggest stopping the medication, even if helpful for those symptoms, if perceived to cause side effects detrimental to performance. Additionally, when the athlete suffers a defeat in sport, their ‘need’ for attention from the athletic trainer may appear to increase significantly as they seek to ‘explain’ their failure via apparent physical injury or express any contributing mental health symptoms somatically. While inclusion of these entourage members can be intrusive, they can also become an important component of the therapeutic process by providing supplementary information and supporting adherence with treatment recommendations.8
Once a basic formulation and diagnosis are made, the next step is to set treatment goals, which allow the athlete-patient and the provider to monitor the progress of their work together.22 Goals represent the results the athlete wants to achieve and require making a commitment to a course of action and an outcome. Goals may include agreement on substance use; stress control; conflict resolution/crisis intervention; sleep and energy management; injury recovery and pain management; mental preparation; mental health symptom or disorder treatment and advice about team composition, dynamics and unity.22
The literature regarding psychotherapeutic interventions (eg, individual, group and couple/family psychotherapy) in elite athletes is sparse and largely anecdotal.23 24 This is in sharp contrast to the consensus that these forms of treatment can be cost-effective and safe in the general population.25 26 Exceptions to the anecdotal nature of the evidence base include a study by Heird and Steinfeldt (2013) in support of psychotherapy with athletes, identifying athletes as good potential cognitive behavioural therapy candidates.9 27
After goals are set, psychotherapeutic treatment may proceed. There is increasing acceptance that some mental health symptoms and disorders, like some other medical symptoms and diseases, benefit from long-term treatment, possibly over a lifetime.28 This guiding principle may be true for athletes with more severe mental health symptoms and disorders in particular, but long-term psychotherapy with athletes has received minimal study. Conversely, literature from the general population29 suggests that brief psychotherapy may decrease many mental health symptoms and disorders in elite athletes.
In many situations—whether athletes or non-athletes—the preferred intervention may be integrative, combining psychotherapy with pharmacological intervention.30 Prescription of both psychotherapy and/or medication should focus on the risks and benefits of that intervention for an elite athlete.31 Clinicians should not recommend non-scientific, ‘alternative’ treatments, when the risks are unknown, the benefits are only associated with ‘anecdotal reports’, and there is no supporting evidence even from the general population.32 There are multiple randomised controlled trials of psychotherapy in non-athletes,33 but there is little literature on which elements of psychotherapy might be most helpful for elite athletes. Developing some degree of ‘insight’ (an understanding of how their feelings, beliefs, actions and events from the past are influencing their current mindset), regardless of type of psychotherapy, may be an important variable associated with good outcome.34
Some athletes or clinicians may prefer simple pharmacological intervention for mental health symptoms or disorders, but such treatment may be insufficient as a singular intervention.30 Moreover, elite athletes have sport-specific medication considerations, for example, antidoping regulations and the desire for avoidance of side effects that could negatively impact athletic performance.8 Some of the side effects of particular relevance and concern for elite athlete include sedation, weight gain and tremor.8 Thus, efforts to engage the athlete in psychotherapy helps to ensure best practice, provide the most comprehensive and empirically supported treatment approach and undertake motivational enhancement for adherence to any needed medication recommendations.20 35
Individual psychotherapy (often brief or short-term) specifically is effective to treat mental health symptoms and disorders and to improve adherence to medication when indicated.35 36 The most common types of individual psychotherapies used in young adults, college students and collegiate athletes by a range of mental health providers are supportive, cognitive behavioural (CBT), motivational enhancement (MET) and psychodynamic.37–40 In general, these therapies appear to have common healing factors, including: (1) affective arousal; (2) feeling understood by the therapist; (3) offering a framework for understanding the problem/solution; (4) therapist expertise; (5) therapeutic structure/procedures; (6) optimism regarding improvement and (7) experiences of success.37
Supportive therapy allows patients to express and understand their emotions, use their support network and strengths and experience empathy from another person.37 CBT uncovers how a patient’s dysfunctional thoughts lead to negative emotional activation and maladaptive actions or inactions.40 MET aims to help patients identify and resolve their ambivalence towards change, thereby increasing their readiness and confidence via the therapist asking open-ended questions, affirming positive insights and actions, practicing reflective listening and summarising old and new perspectives.35 Finally, psychodynamic therapy helps a patient understand how previous repetitive psychological and interpersonal conflicts play themselves out in the present, resulting in symptom activation and dysfunction.37–41
For certain common issues in elite athletes (eg, mild depression, anxiety, insomnia, anger or sports-related adjustment issues), individual psychotherapy alone may be sufficient as a treatment approach.1 Athletes may be especially appropriate candidates for CBT because they are accustomed to structure, direction, practice, goal setting and self-reliance42 CBT appears most useful for substance use disorders, insomnia, anxiety, depression, anger/ aggression, somatisation, chronic pain and general stress—all common in elite athletes.38 41 MET appears most useful for patients with risky drinking and adverse alcohol behaviours; for individuals with tobacco cessation as a goal and for medication adherence issues. Fewer data are available for supportive and psychodynamic therapies in general.43
Despite the apparent benefits of individual psychotherapy in the general population, no controlled studies were found on the use of individual psychotherapy for treating mental health symptoms and disorders in elite athletes. Some small trials of brief motivational interventions for binge drinking among American collegiate athletes (sometimes with the inclusion of coaches or parents) had promising results.44–46 Conversely, there is a plethora of research on individual mental skills training for athletic performance enhancement.47
Couple/family psychotherapy may be helpful with elite athletes. It is important to have a clear understanding of the impact that an athlete’s significant other(s) have on an athlete’s mental health symptoms and disorders (and vice versa). Many times, these influences can be a large reason, or the sole reason, that an athlete will seek or participate in treatment.8 While inclusion of these individuals may be viewed as intrusive, they may have a large influence on the day-to-day life of the elite athlete and their treatment adherence.1 However, no controlled research concerning involvement of an athlete’s family or partner(s) in treatment was found. The case example below highlights the important role of the athlete’s family in determining the course of their treatment:
Case e xample: An athlete’s wife called one of the authors to evaluate her elite-athlete husband. She was under extraordinary stress due to the illness of her mother, and the family dynamics of the household changed considerably when her mother was brought into the home full-time. In addition to individually perceived stress, this situation negatively affected the athlete’s relationship with his wife; this stress began to harm the athlete’s sense of well-being and performance. The mother and daughter then began individual psychotherapy, which provided key insight into coping skills. The athlete also received short-term psychotherapy, which helped him to understand the interplay of personal/family stress and athletic performance.
Group psychotherapy is often indicated as an adjunct to medication, especially for substance use disorders, and can be best facilitated by a licensed mental health professional with relevant qualifications and/or experience.8 Moreover, athletes involved in team sports may be particularly responsive to health professional-led groups, as they are accustomed to the team-coach dynamic, in which the ‘team’ is led by the ‘coach’.8 These groups can also provide psychoeducation to elite athletes about mental health symptoms and disorders and their respective treatments.22 With highly recognisable athletes, anonymity and confidentially are often problematic in group settings and can be a deterrent to this form of therapy.16 If the athlete has had positive past experiences with this type of therapy and is assured that the service can be offered confidentially and can be well integrated into the athlete’s life, they are more likely to agree to this approach.21
Challenges associated with psychotherapy with elite athletes
Working with elite athletes presents specific circumstances and challenges for mental health professionals providing psychotherapy.
There are many sport-specific challenges with mental health diagnosis of elite athletes, and it is important to have an accurate diagnosis before beginning psychotherapy.16 For example, ‘overtraining syndrome’ and clinical depression may present similarly, with fatigue, insomnia, weight change, appetite loss, cognitive deficits and lack of energy or motivation.8 When overtraining is an important underlying issue for the athlete, psychotherapy for depression may be ineffective.9 48
Another sport-specific diagnostic challenge in elite athletes is ritualistic and obsessive-compulsive behaviours. Domotor and colleagues stated that athletes who perceive a contest as uncontrollable tend to ascribe more control to external factors, which prompts them to engage in superstitious behaviours.49 Stillman et al recommend that clinicians distinguish between superstitious behaviour that happens exclusively in the context of sport and obsessive-compulsive behaviours, as the latter often involve overall life impairment.8 It is important for the clinician to have an awareness that many ritualistic behaviours of elite athletes are ‘normal’ and not to overpathologise what may appear to be manifestations of an obsessive-compulsive disorder (OCD). For example, routines that basketball players may perform in the moments before shooting the ball may serve as a method to focus their full concentration and regulate their shooting technique, whereas patients with OCD present a pathological tendency towards repetitive behaviour or thought patterns that causes significant distress or dysfunction. Psychotherapy that inappropriately addresses non-problematic superstitious rituals as OCD may be ineffective and may weaken an athlete’s relatively healthy coping strategies.
A diagnostic issue largely unaddressed in the literature is whether elite athletes within different sports have different risks for various mental health symptoms and disorders. It might be logically expected, for example, that football linebackers, marathon runners and ski jumpers would typically face different sets of challenges and thus be at differential risk for a variety of mental health symptoms. Some research suggests that individual sports might confer greater risk for depressive symptoms compared with team sports,50–52 but the cause of any such greater risk in the former group is unknown, and thus it remains difficult to address causative factors within psychotherapy. Nonetheless, an understanding of the particular stressors commonly found within a given sport might inform psychotherapeutic approaches with an athlete participating in that sport.2
Deterrents to help-seeking
Athletes can be reluctant to seek help for mental health symptoms and disorders when they perceive their behaviours to positively impact sport performance.18 One example is athletes who use anabolic steroids or other performance-enhancing substances, which can impair mood.53 Additionally, athletes with eating disorders may have difficulty seeking help because they feel that these eating behaviours help them with performance, improve their aesthetics or help to make a weight class.54 As noted earlier, additional deterrents to help-seeking include fewer positive attitudes towards mental health services than the general population,18 fear of not being allowed to participate in sport,19 and the idea of receiving care for mental health may seem ‘weak’, as going to a mental health professional is commonly viewed as evidence of being ‘crazy’ or untrustworthy.16 These factors, coupled with a sense of invincibility and/or a lack of thinking about or planning for the future, create major barriers for elite athletes to start psychotherapy.16
Narcissism and aggression
Elite athletes are often held in high regard by the public and by their core support team. Such adulation can become a barrier to mental health intervention, as it may lead elite athletes to believe that they do not need assistance or to expect unrealistically favourable and rapid responses to psychotherapy.16 While not true of many elite athletes, at the extreme, athletes may develop grandiose fantasies, demonstrate diminished ability to empathise and respond with fury to slights, both real and imagined.8 Sofia and Cruz (2017) demonstrated a positive relationship between anger, aggressiveness, general aggressive behaviour, antisocial behaviour towards opponents and teammates and the experience of and expression of anger.55 This finding supports previous research that antisocial traits can often lead to anger outbursts, especially within training, practices and games;8 psychotherapists may be asked to address these issues with their athlete-patients and may simultaneously experience these issues as challenges within the psychotherapeutic relationship.
Expectations about services
Elite athletes may expect accommodations within psychotherapy not available to non-athlete patients.16 For instance, although sometimes financially well off, elite athletes may not be accustomed to paying for certain services; they may offer game tickets or other merchandise in exchange for services.8 Due to frequent travel for competition and training, elite athletes often have personal assistants who manage daily tasks for them. Such a situation can create a challenge if direct communication with an athlete, rather than a personal assistant, would be prudent. Athletes may request treatment based around their schedule and in a geographic area they choose, both of which can be difficult for clinicians to navigate in an effort to avoid boundary problems.16 Phone or video sessions are sometimes permissible second choices. Clinicians should carefully weigh the advantages and disadvantages of providing psychotherapy for any patient outside of their usual office practice.8 Ultimately, it is recommended that clinicians balance ‘flexibility with appropriate boundaries’ when undergoing psychotherapy with elite athletes.16
New trajectories in psychotherapy
Several issues within elite sport have potential mental health implications, and while not addressed in this review due to lack of research related to psychotherapy, they warrant acknowledgement. One prevailing issue is the sexual abuse of elite athletes, particularly female gymnasts—a problem that also exists among elite woman and men in other sports56 57 Such abuse would be expected to adversely affect the mental health of these athletes58 and merits future research regarding factors that might be addressed with psychotherapeutic treatment. Another major issue worth mention for its association with mental health symptoms and disorders is sport-related concussion (SRC).59 Research regarding mental health services for athletes with or at risk for SRC-associated mental health symptoms or disorders should be a priority. Finally, the issue of black athletes protesting discrimination in society and sport has come to recent attention in American football and basketball. This may pose a mental health risk for black athletes because of conflicts between loyalties to their race and loyalty to their team. Psychotherapeutic strategies to address these conflicts should be studied, both on an individual level and on a systemic level, given the implications that these issues could have on individual athletes, sport teams and society at large.
Summary and conclusion
Elite athletes have mental health symptoms and disorders that can and often should be treated with psychotherapy, with or without pharmacological treatment. Psychotherapy with elite athletes must address sport-specific needs and challenges. Mental health professionals, other healthcare professionals and other members of the athlete entourage should work together to address mental health symptoms and disorders in elite athletes, just as other healthcare professionals treat physical injuries in athletes. For the assessment and management of the mental health needs of elite athletes to be on par with other physical needs, more high quality epidemiological and treatment intervention studies are needed. Development of specific models of intervention for elite athletes with significant mental health symptoms and disorders is necessary. These interventions may include individual, couple/family and group psychotherapy, using evidence-based treatments that are reasonably accessible.
Considering that the prevalence of mental health symptoms and disorders in elite athletes appears to at least parallel that of the general population (about 20%–25%),4 we propose the aspirational recommendation that mental health clinicians with comprehensive treatment expertise be included on the medical staff of every elite sports team or organisation.4 Previous researchers have recommended that mental health services should be available year round, on-site at both the training facility and/or the site of competition, and that services should address common issues such as stress, substance misuse, insomnia, low energy, injury, team conflict and lack of motivation.22 Presently, many elite sport teams have requirements for a variety of clinical services, including sports medicine physicians, athletic trainers, orthopaedic surgeons, dentists, dieticians, physical therapists and chiropractors. If mental health services are provided and care is integrated with other team clinical and administrative staff, then utilisation rates and satisfaction with services may be high.22 In an effort to destigmatise mental health, normalising it via inclusion of a mental health clinician as a member of the medical staff would be ideal.
What is already known
Elite athletes, like non-athletes, suffer from mental health symptoms and disorders and may benefit from treatment with individual, couple/family or group psychotherapy.
The role of and input from the athlete’s family and other support systems when undergoing psychotherapy with athletes are important.
Elite athletes may present specific treatment challenges and concerns in psychotherapy, including diagnostic challenges, deterrents to help-seeking, narcissistic and aggressive personality features and expectations about services.
What are the new findings
An integrated (multidisciplinary) treatment approach, centred on a broadly based diagnostic workup (usually including psychotherapy and sometimes coupled with psychopharmacological treatment), should be recommended to elite athletes with mental health symptoms and disorders.
Psychotherapy for elite athletes should be part of a comprehensive treatment plan for mental health symptoms and disorders that is delivered by a multidisciplinary team.
The authors thank the other participants in the 2018 International Olympic Committee Consensus Meeting on Mental Health in Elite Athletes, including Cindy Miller Aron, David Baron, Antonia Baum, Abhinav Bindra, Richard Budgett, Niccolo Campriani, Joao Mauricio Castaldelli-Maia, Alan Currie, Jeff Derevensky, Lars Engebretsen, Paul Gorczynski, Vincent Gouttebarge, Michael Grandner, Doug Hyun Han, Margo Mountjoy, Aslihan Polat, Rosemary Purcell, Margot Putukian, Simon Rice, Allen Sills, Torbjorn Soligard, Todd Stull, Leslie Swartz and Li Jing Zhu, for their helping us develop and interpret this research.
Contributors MAS, IDG, DM, CLR, MEH, VMF and BH all contributed to the writing of the manuscript. All authors helped perform the literature search and write the article. MAS and IDG had the idea for the article and MAS is the guarantor. Each author’s contribution to the paper is listed and described below. All authors are in agreement with the content of this manuscript. MAS: conception, design, construction and interpretation of the study; revising the article; final approval. IDG: review of the literature; construction of the article; revising the article; final approval. DM: review of the literature; interpretation; constructing and revising the article; final approval. CLR: conception and design of the study; construction of the article; revising the article; final approval. MEH: construction of the article; revising the article; final approval. VMF: review of the literature; constructing and revising the article; final approval. BH: construction of the article, revising the article; final approval.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.