Evidence-Based Psychotherapy Practices for Preschool Children: A Brief Review for Clinicians

Despite growing consensus that clinical interventions must be supported by empirical evidence, preschool-aged children are more likely than older children to receive services with little to no empirical support. The dissemination of research findings on the efficacy of specific interventions is constrained by clinicians’ limited access to peer-reviewed research journals and treatment manuals. The current paper provides a synthesis on the literature of psychological treatment for children with externalizing or internalizing problems and their parents or families. The review highlights key principles and treatment approaches that are supported by the evidence so that clinicians may readily implement these evidence-based treatments. The approaches that have the most empirical support for externalizing problems are parent behavior management training (PBMT), parent-child interaction therapy (PCIT), and cognitive behavioral therapy (CBT; in individual or group format, including social skills groups). For internalizing problems, research suggests that family-based CBT, group parent CBT (alone or in combination with group child CBT), trauma-focused CBT, and adapted versions of PCIT are the most evidence-supported treatments in preschool children. Common principles and techniques that are shared by a number of evidence-based treatments for preschool-aged children, and recommendations for clinicians and for the research community are discussed.

Introduction

Early childhood is a key developmental period during which many mental health problems emerge for the first time [12]. Mental health difficulties at this point in life are predictive of continued problems later in development [e.g., 56]; as such, early and effective intervention is critical. As preschool-aged children are highly sensitive to their environment (e.g., household organization, parenting style, and peer relationships) [35], early intervention at this stage can have a clinically meaningful and long-lasting impact on preschoolers’ wellbeing [10].

Externalizing and internalizing problems represent two clusters of psychological disorders requiring early identification and intervention in this age group. Externalizing problems characterized by behavioral dysregulation, poor impulse control, aggression, and defiance are the most common reason for parents of preschoolers to seek therapy and counseling [36; 74]. Internalizing problems are characterized by negative affectivity. They include depressive and anxiety symptoms [22], which also commonly prompt parents to seek professional help for their preschool-aged children, with prevalence rates of about 10% in this age group [25]. While intervention research for these two clusters of psychological problems among school-aged children and adolescents is extensive [e.g., 32; 53; 82], such intervention research efforts for preschoolers are relatively lagging in comparison. As this body of literature has developed in recent years, a synthesis of the current state of science is called for.

Despite growing consensus that clinical interventions must be supported by empirical evidence, preschool-aged children are more likely than older children to receive services with little to no empirical support [1; 79]. This can be attributed, in part, to a gap between research and implementation in clinical practice [14; 84]. A number of published randomized controlled trials and meta-analyses have demonstrated the efficacy (or lack thereof) of interventions for externalizing and internalizing problems in preschoolers
[3; 27; 28; 34; 77].

However, the dissemination of these findings is constrained by clinicians’ limited access to peer-reviewed research journals. In addition, journal articles reporting on clinical trials typically do not include sufficient detail required for clinicians to apply the techniques in their routine interventions. Moreover, treatment manuals that do include such details may not be readily available or accessible to clinicians wishing to implement evidence-based approaches due to financial, organizational, or geographic barriers. Treatment manuals are numerous, and many are based on overlapping behavioral principles and mechanisms of change (i.e., “common elements”; [40; 60]). Thus, a synthesis of the literature highlighting key principles and treatment approaches that are supported by the evidence may allow clinicians to readily implement them.

Existing reviews of evidence-based treatments for childhood internalizing and externalizing problems have typically categorized any child under the age of 13 years as “children” ([e.g., 29; 32; 72; 82; 87]; with the exception of a review by Eyberg et al. [28] on disruptive behavior treatment, which identified programs geared towards 2–5-year-olds). Most existing reviews thus have not examined specific treatment effects for preschool-aged children younger than 6 years. Given significant developmental differences between preschool-aged children and school-aged children, this is a gap that warrants attention. Among reviews that have specifically focused on preschool-aged children, these reviews have focused on a particular disorder (e.g., anxiety disorders [18]) or treatment approach (e.g., cognitive-behavioral intervention for anxiety [77]). Furthermore, describing the principles and shared elements of these evidence-based interventions has typically been outside the scope of these existing reviews (e.g., [83]). The present review fulfills an unmet need for a synthesis of the literature on evidence-based treatments for preschoolers that details their shared principles in sufficient detail to be implemented by clinicians.

The aims of this review are to: 1) inform clinicians on the current state of the literature; 2) provide clinicians with the information needed to evaluate available treatment approaches and make informed decisions in selecting evidence-based interventions; and 3) describe principles and techniques underlying these evidence-based interventions.

Evidence-Based Practices for Externalizing Problems in Preschool Children

Externalizing behavior problems refer to a group of aggressive or impulsive behaviors that are aimed at the outward (or external, as the term suggests) environment. They include disruptive behavior, hyperactivity, and aggression [48]. The process of gaining autonomy from an attachment figure and exploration typically involves testing boundaries [17; 52]. Therefore, in the context of preschool-age children, it is important
to distinguish between developmentally appropriate manifestations of defiance and problematic behaviors. Typically, when the magnitude and/or frequency of temper tantrums, aggressive behaviors, or disobedience are significant, parents tend to seek professional advice [64]. The mean prevalence of externalizing behavior problems in preschool children is estimated at 9% [25].

Generally, mental health problems of young children are viewed through the dimensional lens of developmental psychopathology that focuses on symptoms rather than distinct diagnostic categories. Preschool children rarely receive formal diagnoses such as attention-deficit/hyperactivity disorder (ADHD) or oppositional defiant disorder (ODD) prior to placement in a more rigorous academic environment [86]; however, they may exhibit poor impulse control, defiance, outward aggression, and behavioral dysregulation, which fall under the umbrella of externalizing behavior problems. Importantly, evidence-based techniques that are applied to externalizing behavior problems can be used regardless of the magnitude of the problem or the presence of a diagnosis. Below, we review evidence-based principles and interventions for ADHD and temper tantrums, as well as aggression and defiance (for further information about externalizing problems in children, see [8]).

Parent Behavior Management Training

In severe cases in which children fail to pay attention or control their motor agitation, parents may seek intervention before children begin school, even though the ADHD diagnosis is typically given after children have entered structured classroom instruction. Parent management training and behavioral classroom interventions (if children are attending preschool) are considered frontline interventions for ADHD in this age group.

The common underlying principle of all evidence-based interventions for ADHD is the implementation of structure and consistency [26]. Strategies aimed at the attentional component of ADHD include establishing eye contact, using visual reminders, creating checklists, scheduling breaks, and alternating between activities using timers. Techniques that address hyperactivity include establishing explicit rules, ignoring mild misbehavior, and providing labeled praise for desired behavior [71]. As working memory is implicated in ADHD, the use of simple, specific instructions that do not include multiple steps is encouraged to minimize information overload. Parent training for ADHD is a brief intervention (up to 10 sessions) that is done either in a group format or individually and includes behavior modification [86]. Given that ADHD is highly heritable [42], parent training has the added value of teaching parents themselves how to structure their environment and establish routines; such parenting practices play an important role in remediating the symptoms of ADHD in children.

For older age groups (ages 6–12 years), the combination of behavioral interventions and medication may lead to maximized treatment gains of ADHD: specifically, adding medication secondary to initial behavior modification results in better outcomes in oppositional behavior [62]. However, for preschoolers (ages younger than 6 years), the recommendation remains to start with behavioral interventions and later supplement these with medications (i.e., methylphenidate in particular [86]) if behavioral interventions alone do not lead to significant improvement [2]. However, given recent concerns with the overprescription of stimulants to youth [4] and the potential neurological and psychiatric side effects of long-term methylphenidate use in preschoolers (see [41] for a review), caution is advised when prescribing stimulant medication to this population.

To address temper tantrums and defiance, the use of parent training in behavior modification (PTBM) is recommended [37]. PTBM is an evidence-based approach that can be used regardless of the presence of the diagnoses. In fact, it is advised to intervene before the diagnosis of ODD is given. In PTBM, parents are taught how to handle specific behaviors and how to effectively set limits. It utilizes principles of behavioral psychology, such as the use of contingencies, reinforcement, negotiation, and contracts, among others.^[1] First, the intervention focuses on repairing the relationship between children and parents by engaging in “special time.” Special time is a period of time set aside each day, during which children are provided with a unique opportunity for positive attention and freedom of choice in activities. Providing positive attention and putting children in charge allow parents to provide children a sense of agency and trust, which is the first step in rebuilding the parent-child relationship. Parents are advised to refrain from using questions or directions during the special time. Special time is implemented on a consistent basis regardless of how a child behaves during the day.

Next, behavior modification techniques are introduced. Generally, all behavioral techniques capitalize on the principles of operant conditioning [37]. They postulate that the consequences of behavior either increase or decrease the frequency of future behaviors. The first step in modifying undesired behaviors involves ignoring. Parents are encouraged not to engage with children in any way until they stop undesired behavior. When ignoring is used, parents are prepared for an extinction burst, which refers to an increase in the undesired behavior. Like all other behavior techniques, ignoring needs to be applied systematically and consistently (across time and settings) until the behavior is extinguished. Ignoring problematic behaviors is paired with praising desired behaviors. Importantly, ignoring is not recommended when the child is posing a danger to themself or others (e.g., hurting others, running onto a street); in such instances, parents are taught to set firm limits using time-outs (i.e., placing the child in a setting without reinforcements for a specified number of minutes) and time-out warnings (i.e., a statement warning the child of an impending time-out unless they follow directions).

Parents are also taught behavioral techniques to increase desired behaviors. For example, how to provide labeled praise so that children know what specific behavior triggered it. Another effective technique is the token economy, which is a system to reward children for behaving in desired ways. To establish a token economy, parents and children collaboratively assign certain values to different chores and activities that the child is supposed to do, for which they receive points/tokens. Children can exchange their acquired points/tokens for rewards from a predetermined list of activities, prizes, or privileges. After the token system is in place, parents are encouraged to have a conversation about the behavior response cost, which is the removal of privileges after specific undesired behaviors (which are also negotiated with the child in advance).

A recent meta-meta-analysis, in which the authors combined all meta-analyses published on the topic until 2018 [57], evaluated the effectiveness of parent training interventions for children with externalizing behaviors. A moderate effect size (standardized mean difference [SMD]=0.45, 95% confidence interval [CI]: 0.35 to 0.55, p<.0001) was found for parent-based interventions for externalizing behavior problems of children under 13 years of age, and this effect was stable at follow-up from 1 to 72 months post-treatment.

Parent-Child Interaction Therapy (PCIT)

An alternative intervention for externalizing behaviors is Parent-Child Interaction Therapy (PCIT), which is parent training done in vivo [46]. PCIT typically consists of two phases. In the child-directed interaction phase, parents are taught selective attending for the purpose of improving the parent-child relationship. The main approach in this phase focuses on ignoring undesired behaviors (e.g., tantrums) and reinforcing positive, appropriate behaviors (e.g., verbalizing anger). Next, during the parent-directed interaction phase, parents are taught how to implement effective discipline strategies. Both phases typically begin with a didactic, followed by parent-child interaction in which parents put these lessons into action; a clinician observes the parent-child interaction and provides recommendations and feedback to parents in real-time using a “bug in the ear” device. The intervention is typically used with children from 2 to 7 years of age. A meta-analysis demonstrated that PCIT is effective in decreasing problematic externalizing behaviors (standardized mean difference [SMD]=-0.87, 95% CI: -1.17 to -0.58) [75]. One example of programs that include components of both PCIT and PTBM is the Incredible Years Program [81]. The goals of the Incredible Years Program are to promote the values of positive parenting and to coach parents how to effectively communicate with their children. This is accomplished by providing parents didactics and by watching and discussing videos of parents’ interactions with their children. The Incredible Years program has been successfully implemented with families of diverse cultural backgrounds [44].

Social Skills Groups

Social skills groups are an intervention frequently used with children with aggressive and defiant behavior [43]. Social skills interventions for preschool-aged children typically teach children effective communication skills by exposing them to ecologically valid stressors. These include negotiating with peers, taking turns, being assertive, and understanding boundaries. Social skills groups teach children emotion regulation techniques such as taking breaks and verbalizing frustration instead of acting out physically. Groups typically range in size from 6 to 10 children. In social skills groups, children receive instant feedback from their peers and the therapists. The benefits of social skills groups have been widely studied in the context of ODD and CD in older youth. A recent meta-analysis on the efficacy of social skills training for externalizing problems examined 98 studies, of which 22 studies included children under the age of six [9]. This meta-analysis found that, in general, adolescents (ages 16 and above) benefited more from the interventions than younger youth. However, a small positive effect of social skills groups on aggressiveness, antisocial behavior, delinquency, and oppositional behavior was also observed in preschool-aged children (Cohen’s d=0.15±0.18) [9]. The findings from the literature regarding the efficacy of social skills groups are mixed; some studies have found a “peer contagion effect,” which refers to the exacerbation of aggressive behavior in youth who are placed in environments with deviant peers [24]. The peer contagion effect is observed especially when aggressive children are clustered together into intervention groups in a homogenous manner [45]. While studies reporting peer contagion typically involve samples of adolescents, there is also evidence that young children can learn aggressive behavior through modeling [61]. As such, more research is needed to better understand the mechanisms and the circumstances in which peer contagion is more likely.

Of note, the cognitive component is not emphasized in the evidence-based interventions for preschool-children with externalizing behavior problems. A recent meta-analysis on the effectiveness of cognitive-behavioral therapy (CBT) for externalizing problems demonstrated that the cognitive aspect of therapy is introduced in most studies once children reach school age [7]. As such, when treating externalizing behaviors in younger children, it is commonly the parents’ maladaptive cognitions that are addressed in lieu of the child’s (e.g., encouraging a parent to cognitively reframe their child’s acting out as a request for attention, rather than an attempt to upset the parent). Taken together, behavioral interventions have the strongest evidence for treating preschool-aged children with externalizing behaviors. These interventions are relatively cost-effective and brief.

Some interventions that do not have sufficient evidence of effectiveness for treating externalizing behaviors in preschool children include play therapy, pet therapy [38], sensory integration (which is especially popular in the context of ADHD), and dietary modifications [13]. While the listed approaches are not harmful [88], their efficacy is inconclusive or has not been demonstrated for externalizing behavior problems.

Evidence-Based Practices for Internalizing Problems
in Preschool Children

Early identification and intervention for internalizing problems (i.e., anxiety and related problems and depression) in preschool children are critical, given that untreated internalizing problems are chronic and impairing [50; 78]. When assessing anxiety-related problems in preschool children, it is important that clinicians distinguish between developmentally appropriate fears and problematic anxiety. Fear of the dark may be expected of a 2-year-old child, whereas this same fear may be less appropriate for
a 10-year-old child, for instance.

The four most common anxiety disorders in preschool-aged children are separation anxiety disorder (fear of separation from attachment figures), social anxiety disorder (fear of one or more social situations), generalized anxiety disorder (excessive anxiety and worry about a number of events), and specific phobia (marked fear of a specific object or situation) [22; 83]. Notably, separation anxiety problems typically manifest between the ages of 5−7 years (i.e., when children begin attending school) in the form of school refusal [20]. While less common, selective mutism (failure to speak in specific social situations where speaking is expected) is another anxiety disorder that onsets typically in the preschool years [80] (for additional information about childhood anxiety disorders, see [55]).

Contrary to initial beliefs that preschoolers are not cognitively capable of experiencing depression, research has found that depression can indeed affront children as young as 3 years [83]. Depression in preschoolers may present differently from depression in older youth that clinicians typically encounter, but several key markers distinguish depressed preschoolers from their non-depressed peers: decreased energy, increased anhedonia, irritability, excessive guilt, and engagement in activities or “play themes” related to death or suicide [51; 83] (for additional information about childhood depressive disorders, see [65]).

Below, we review evidence-based approaches for treating anxiety and related problems and depression in preschoolers. The DSM-5 no longer categorizes obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD) as anxiety disorders; however, symptoms of these two disorders can onset in preschool [19; 70], and the principles of evidence-based treatment of these problems overlap with those for anxiety disorders. As such, in this review, we conceptualize these problems as falling under the umbrella of “anxiety and related problems.”

Cognitive Behavioral Therapy

The past two decades have seen an increase in research testing the efficacy of psychotherapy treatments for preschool anxiety and related problems. CBT-based treatments have the greatest empirical support for treating this cluster of internalizing problems in preschool children. Specifically, family-based CBT is efficacious in treating various types of anxiety and related problems, including separation anxiety, social anxiety, behavioral inhibition, generalized anxiety, phobias, selective mutism, mixed anxiety symptoms, traumatic stress, and OCD symptoms [18]. Family-based CBT primarily involves only the therapist and the child’s parents, although it can also involve the child (e.g., “Being Brave” program; [33]). Other CBT-based treatments for preschool anxiety and related problems include group parent CBT (alone or in combination with group child CBT) and trauma-focused CBT [18].

Family-based CBT. One of the key principles of family-based CBT for anxiety-related problems is reducing problematic parenting behaviors that (inadvertently) contribute to young children’s anxiety. A common example of such parenting behaviors includes parental overprotection, in which parents attempt to shield their child from anxiety-provoking experiences. Although this decreases the child’s anxiety in the short term, it interferes with the child’s normative development of autonomy and self-efficacy in the process (e.g.,
a mother accompanying her child on all social outings; [16]). Another common example of problematic parenting behaviors is family accommodation, which allows the child to avoid situations that cause anxiety (e.g., allowing the child to sleep with a light every night; [76]). These parenting behaviors may provide the child (and parent) relief in the short term but actually maintains the child’s anxiety in the long term.

In family-based CBT, the therapist first teaches the parent about these problematic parenting practices and their effect on the child’s anxiety. Thereafter, the therapist teaches the parent how to encourage the child to face their fears instead, in an effort to teach the child that their fears are manageable and/or unsubstantiated. Parents and children develop a fear hierarchy (or “fear ladder”), which allows them to complete exposure exercises starting with relatively low fear-provoking stimuli (e.g., for a child with a dog phobia, seeing a photograph of a dog) to greater fear-provoking stimuli (e.g., petting a dog).

In a recent systematic review, 38 treatments in samples of children with a mean age of under 8 years (N=2,228 children) were evaluated and classified according to one of five levels of empirical support: well-established, probably efficacious, possibly efficacious, experimental, or of questionable efficacy [18]. The first three levels of treatments have demonstrated varying degrees of efficacy in randomized controlled trials (see [73] for details), “experimental” treatments have not been tested in a randomized controlled trial or otherwise do not meet the criteria to be possibly efficacious, and treatments of “questionable” efficacy are found to be inferior to other treatments or control groups. In this review, family-based CBT was the only treatment classified as “well-established” [18]. Indeed, the efficacy of CBT for preschool anxiety is supported by a recent meta-analysis of 42 samples (N=2,611; SMD=-0.81 compared to control conditions) [77].

Family-based CBT is also the most strongly empirically supported treatment for early-onset OCD in children aged 5–8 years [31]. It draws on the principles of CBT for OCD in older youth; as such, a core component of treatment is exposure and response prevention (ERP; [31]). ERP involves the therapist and parent assisting children to challenge fears through facing obsession-provoking situations (“exposure”) while reducing or eliminating compensatory compulsions and avoidance (“response prevention”). For example, in treating a child with cleanliness-related obsessions and compulsions, the therapist may coach the parent to assist their child to touch a restroom floor (exposure) without washing their hands for a specified amount of time (response prevention).

Family-based CBT for early-onset OCD differs from CBT for OCD in older youth in several ways. First, the therapist uses concrete and “child-friendly” metaphors to educate children on the connections between obsessions and compulsions (e.g., obsessions are
a “worry monster” and tell one to do things) and explain the benefits of ERP exercises
(e.g., akin to a “yucky” medicine that makes one feel better; [5]). Second, therapists extensively involve parents as “coaches” who ensure the child adheres to treatment outside of sessions. Third, therapists address parental accommodation of child OCD behaviors. Finally, therapists address parents’ own exposure to their own distress in response to their child’s distress during ERP exercises [5].

Group CBT. CBT for preschool anxiety and related disorders has also been adapted to group formats to allow treatment delivery to multiple families at once. Group CBT, whether it involves only parents, or involves parents and children, is classified as a “possibly efficacious” treatment for preschool anxiety and related problems [18]. Group parent CBT is efficacious for social anxiety/behavioral inhibition and mixed anxiety symptoms, and group parent CBT in combination with group child CBT is efficacious for separation anxiety, social anxiety/behavioral inhibition, worry/fear/generalized anxiety, phobias, and mixed anxiety symptoms (e.g., Fun FRIENDS program, Turtle Program; [5; 15; 18]). Group parent CBT and group child CBT address much of the same domains as family-based CBT, in addition to addressing parents’ own anxiety. Another key feature of group parent CBT sans children is that exposure exercises are assigned to parents to conduct in between sessions, rather than conducting exposure in vivo (i.e., within the session with
the child).

Trauma-focused CBT (TF-CBT). TF-CBT is the most strongly empirically supported treatment for preschool PTSD [69]. TF-CBT is a short-term, structured treatment developed for young children impacted by trauma and their caregivers. It addresses posttraumatic symptoms and other affective symptoms related to the trauma by teaching children skills to manage difficult emotions and reduce negative patterns of behavior stemming from the trauma. Specifically, TF-CBT has been tailored for preschool-age children by 1) using a cartoon-based narrative to address the trauma; 2) co-constructing
a book with the child’s narrative of the trauma; 3) considering the parent’s own trauma and trauma recovery; and 4) showing the parents a videotape of their child narrating the trauma, in later stages of treatment [68]. Variants of TF-CBT for preschool PTSD, which also have empirical support, include family-based TF-CBT (i.e., joint child-parent sessions) with or without a trauma narrative component [21] and stepped-care TF-CBT [67], which titrates the intensity of treatment according to the child’s level of severity or need (and thus, reduces delivery costs as compared to typical TF-CBT). A recent systematic review of trials of TF-CBT for PTSD in preschoolers ages 3–6 years concluded that TF-CBT meets the criteria as a “possibly efficacious” intervention for PTSD in this age group [54].

Parent-Child Interaction Therapy (PCIT)

PCIT was originally developed for young children with externalizing problems (see above for a detailed description) but has been adapted for preschool children with separation anxiety [63] and for preschool children with depression [49]. PCIT modified for preschool separation anxiety adds a third phase to the typical two-phase sequence described above. This third phase, titled the “bravery-directed interaction” phase, includes a didactic session that provides parental psychoeducation on the nature of anxiety and the utility of graduated exposure [63]. This session also involves developing a hierarchy of activities the child typically avoids (titled the “bravery ladder”) and a reinforcement system to reward the child for completing exposures (titled “reward stones”). The didactic session is followed by two “coaching” sessions which implement graduated exposure in vivo. As such, this modified PCIT for separation anxiety disorder incorporates elements of family-based CBT while also making use of PCIT’s live coaching model.

To date, PCIT-Emotion Development (PCIT-ED) is the only evidence-based psychotherapy treatment for preschool depression [49]. PCIT-ED is an adaptation of PCIT that is specifically tailored for preschool depression, which adds a third phase titled the “emotion development” module. The ED module aims to improve children’s emotional competence (i.e., ability to identify and understand emotions) and emotion regulation skills. This is done by teaching parents in vivo how to serve as an “emotion coach” and regulate their children’s intense emotions that are specifically related to depression
(e.g., persistent negative affect, sadness, or guilt). A randomized controlled trial found that, compared to a waiting list condition, PCIT-ED lowered rates of depression (odds ratio=9.52, 95% CI [8.44, 10.74]), depression severity (Cohen’s d=1.01, 95% CI not reported), and levels of impairment (Cohen’s d=1.16, 95% CI not reported [49]).

Treatments with Insufficient Support for Preschool Internalizing Problems

Clinicians are cautioned against using treatments with insufficient empirical support. While play therapy is currently widely used with young children with a range of difficulties, including internalizing problems, there is little evidence supporting the efficacy of play therapy for preschool anxiety and depression [83]. While clinical trials have tested play therapy in the treatment of preschool anxiety and related problems, it is currently classified as “experimental” given insufficient empirical support for its efficacy [18]. Likewise, attachment-based therapy is also currently classified as “experimental” in the treatment of preschool anxiety and related problems [18].

It is important to note that CBT, and some CBT-related techniques, are also insufficiently supported for certain internalizing problems in preschoolers. Specifically, relaxation therapy has been classified as having “questionable” efficacy in the treatment of preschool OCD; relaxation therapy was found to be inferior to other treatment groups and waitlist control groups [18]. Moreover, CBT has yet to be adapted and tested for depression in preschool children [83]; this is in part due to the fact that depression was only recently recognized in this age group, and intervention research is still lagging.

Finally, a recent systematic review of 11 studies testing the use of medication treatment for internalizing problems in preschool children noted that this literature is extremely limited and weak in terms of methodological rigor [6]. Additionally, although
a growing number of children ages 2–5 years are being prescribed antipsychotic medication to manage mood, no published clinical trial to date has tested the efficacy and potential harm of antipsychotic medication for very young children with depression [59]. As such, empirically supported psychotherapy is recommended as a first-line treatment, with pharmacologic interventions considered in unique cases and with caution [6].

Discussion

The first aim of the current review was to synthesize the literature on evidence-based approaches to treating externalizing and internalizing problems in preschoolers. The approaches that have the most empirical support for externalizing problems are parent behavior management training (PBMT), parent-child interaction therapy (PCIT), and cognitive behavioral therapy (CBT; in individual or group format, including social skills groups). For internalizing problems, research suggests that family-based CBT, group parent CBT (alone or in combination with group child CBT), trauma-focused CBT, and adapted versions of PCIT are the most evidence-supported treatments in preschool children.

Importantly, an integral component in both internalizing and externalizing interventions for preschoolers is the heavy involvement of parents. Parents are the main figures in the environment of preschool children and thus are the key to their successful socialization and adaptive functioning; therefore, their active involvement in therapy with preschoolers is important. Many parents inadvertently contribute to the exacerbation of problematic behaviors [e.g., 68]; for example, parents of clinically anxious children may enable avoidance of feared stimuli, and parents of children with externalizing problems may reinforce tantrums by responding with attention. For these reasons, the first component of many evidence-based treatments with preschoolers is providing psychoeducation to parents and teaching them new interaction strategies.

The synthesis of the literature revealed several gaps that warrant attention from the research community. First, more clinical trials testing potentially efficacious treatments for preschool depression are needed. Intervention research for preschool depression lags behind that for externalizing problems and anxiety problems, with PCID-ED being the only evidence-based treatment currently available for preschool depression. Adapting and testing CBT for depression in preschool children is an important next step for intervention research. Another future direction for research is studying the efficacy and potential side effects of medication for internalizing problems in preschoolers. Additionally, the research community is recommended to engage in dissemination efforts. Despite research studies that demonstrate the inefficacy of certain treatments (e.g., play therapy) for externalizing and internalizing problems, in practice, such treatments continue to be used in lieu of evidence-based treatments. While this issue is observed in healthcare research as a whole and is not unique to psychotherapy research (e.g., [85]), the research community is encouraged to utilize dissemination practices where possible [66], study the effectiveness of treatments in routine clinical practice, and identify barriers in the implementation of evidence-based treatment for preschool children.

The second aim of this review was to provide clinicians with information to make informed decisions to select evidence-based interventions. To date, there is widespread use of interventions for preschoolers that have little to no empirical support. Such interventions include play therapy, attachment-based therapy, relaxation therapy (in the case of early-onset OCD), sensory integration, animal therapies, and biofeedback. Regarding play therapy, it should be noted that given that play is one of the leading activities for preschool children, elements of play therapy are incorporated into several evidence-based approaches. For instance, PMBT utilizes “special time,” which in essence is a child-centered non-directive play therapy. The first phase of PCIT also uses unstructured play to repair the parent–child relationship. While play is a necessary component of these interventions, the evidence suggests that it is not sufficient to produce the behavioral change needed to alleviate internalizing and externalizing problems. There is growing research in the field examining the efficacy of play therapy and animal-assisted therapy, among others [11; 23; 47; 58]. While it is possible that these interventions may demonstrate an evidence base in the future, currently, they are not recommended for the treatment of internalizing and externalizing problems in preschoolers. Clinicians are strongly encouraged to use empirically supported treatments instead. Professional training to implement several of the empirically supported treatments discussed in this article are available through resources such as Evidence-Based Behavioral Practice (https://ebpp.org), PracticeWise (https://practicewise.com), the Beck Institute (https://beckinstitute.org), and PCIT International (https://pcit.org).^_[2]

The field of research on intervention for preschool internalizing and externalizing problems is still evolving. As new findings from upcoming clinical trials emerge, recommendations may be adjusted. As such, it is important for clinicians to stay up-to-date with the literature as much as possible through methods such as: reading peer-reviewed journal articles through an institutional subscription, in open-access journals, or available from the authors; and reading resources identified in online resource centers (e.g., Substance Abuse and Mental Health Services Administration’s Evidence-Based Practices Resource Center; https://www.samhsa.gov/resource-search/ebp). The American Psychological Association Society of Clinical Psychology (Division 12) provides a free online resource detailing various treatments and their level of empirical support (https://div12.org/treatments/). Additionally, the Blueprints for Healthy Youth Development offers an online database of evidence-based treatment programs for youth (https://www.blueprintsprograms.org).

Finally, the third aim of this review was to provide clinicians with a framework for implementing evidence-based approaches. In this review, we described the principles underlying evidence-based interventions. Treatment manuals and treatment programs frequently share a common treatment approach and techniques at their core [60]. In describing the shared treatment approaches, we highlight that an evidence-based approach to intervention does not necessarily equate to manual-based therapy. While manualized treatments are important in psychotherapy research and helpful in clinical practice, clinicians may be advised to adopt a stance of “flexibility within fidelity” [39]. Fidelity to the treatment approach that is supported by empirical evidence, combined with the flexible application of the approach to the needs and presentation of each patient, will likely yield the best therapeutic outcomes. This is especially the case with treating internalizing and externalizing problems with preschoolers, whose symptom presentations and environments vary widely and represents a still-emerging area of intervention research. To provide the best care possible to this population in need, clinicians are encouraged to apply evidence-based approaches described above in a way that appropriately addresses each child’s and parent’s needs.

^[1] Contingencies refer to consequences that immediately follow a behavior. They are broadly categorized into reinforcers, which aim to increase the frequency of desired behaviors (e.g., verbal praise, material reward), and punishment, which aims to decrease the frequency of undesired behaviors (e.g., reprimand, removal of a toy, time-out). Negotiating refers to the process of establishing explicit rules about rewards for following rules and costs of not adhering to them. A behavior contract outlines parents’ expectations for their child’s behavior and specifies the privileges attached to desired behavior. For an in-depth description of behavioral principles and their application in PTBM [42].

^[2] Resources are provided for informational purposes only and do not constitute an endorsement.

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