1 Introduction

This systematic review explores the experience of psychotherapeutic interventions designed to help children and young people with the psychological difficulties that may result from experiences of interpersonal familial abuse, neglect and adversity in early childhood.

Van der Kolk's (2003) notion of developmental trauma recognizes the neurobiological impact of repeated relational traumas on the developing structures of the brain. A review by Cook et al. (2005) described seven domains of impairment; attachment patterns, biological states and processes, affect regulations, cognitive process, dissociative states, behavioural control and self-concept. The UK Trauma Council (2022) refers to complex trauma as ‘traumatic experiences involving multiple events, with interpersonal threats during childhood or adolescence’. This is a broad definition encompassing familial abuse, neglect and violence but also community violence, racism, discrimination and war. The UK Trauma Council definition is explicit in including experiences of neglect, which is not clearly stated in other definitions of developmental trauma. It also acknowledges socio-political factors and situates relational traumas in a wider systemic context. Complex trauma and developmental trauma are often interchangeable terms with similar definitions. Developmental trauma is not a formal diagnostic term but is a helpful concept that recognizes the importance of formulation which considers past experiences.

Although there are many individualized approaches to supporting and treating developmental trauma, this review focusses on relational interventions that centre on the caregiver–child relationship. Research suggests that the trusted presence of a caregiver can quieten the child's nervous system (Tottenham and Gabard-Durnam 2017). Schore (2021) refers to such interactions as ‘affect synchrony’ and suggests these interactions can generate increasing levels of dopamine arousal, shared emotional states of pleasure and the urge for contact seeking. Informed by such neurobiological research, caregiver–child psychotherapies seek to address some of the common relational mechanisms associated with developmental trauma. The aim of such treatments is usually to support the social and emotional development of the child through increasing relational safety and connection within the caregiver–child relationship. On this basis, some interventions may focus on training of the caregiver to increase understanding of developmental trauma and learn new skills in responding to their child's neurodevelopmental needs without treating the child directly.

Although there are quantitative reviews of the efficacy of psychotherapeutic parent–child treatment models for developmental trauma (Purrington et al. 2023; Wright et al. 2023), less is understood about the conceptual understanding of how the interventions are experienced. This qualitative systematic review aims to synthesize and explore current literature pertaining to caregiver–child psychotherapeutic interventions for developmental trauma with a view to advancing the conceptual understanding of how these interventions are experienced by the clients (caregivers and children), clinicians and referrers who commission the therapies.

2 Method

This systematic literature review (SLR) was registered with PROSPERO, registration number CRD: CRD42023445041. The review is reported in accordance with PRISMA guidelines (Moher et al. 2009).

2.1 Search Strategy

Following Bettany-Saltikov's (2016) approach, a thorough protocol was developed for the review guiding the search strategy, inclusion criteria and data extraction. Search terms and relevant databases were informed by similar review protocols (Purrington et al. 2023: Wright et al. 2023) and developed in consultation with a librarian and co-authors. Search terms were further refined after scoping searches and structured using ‘SPIDER’ criteria (Methley et al. 2014) (see Table 1). Searches were performed in Scopus, APA PsycNET, PubMed, MEDLINE, CINAHL, Social Care Online and Google Scholar. The final search was conducted on 1 September 2023. In addition to this process, titles and abstracts of articles previously identified as relevant were examined for key terms and screened in the same way. To ensure the search was as extensive as possible and in line with the Cochrane Handbook for Systematic Reviews (Higgins et al. 2024), other search strategies that were employed included screening reference lists and citations. Any articles identified through these additional searches were added to Covidence and screened using the same inclusion criteria.

2.2 Data Collection Process

This review was specifically interested in psychotherapeutic treatment models focussed on the dyad of the caregiver–child relationship to treat developmental trauma symptoms. Interventions that did not include the child (such as caregiver groups) were included only if there was a clear focus on strengthening the caregiver–child relationship. Interventions that were solely psychoeducational and did not include a focus on parenting skills were excluded on this basis. Recognizing there was likely to be a paucity of research in this area and to increase the breadth of the review, experiences of ‘clients’—caregivers (e.g., parents, foster carers and residential workers)—as well as clinicians and referrers were included. The experience of clinicians working therapeutically in this dyadic way could increase insight into the value of the approaches or any mechanisms of change. Table 2 provides a detailed overview of the review eligibility criteria.

The term developmental trauma was not always used in the studies. Studies were therefore screened and included if presentations or symptoms were described in a way that was consistent with Van Der Kolk's definition, or symptoms that fitted with Cook's seven domains of impairment, as referred to in the Introduction of this article. This lack of clarity in diagnostic terms is a limitation of both the studies included in this review and the review itself. Initial searches revealed several studies within this subject area were focussed on populations of children in foster care, residential care or adopted. A decision was made to include these as search terms as a degree of relational or developmental trauma could reasonably be assumed in these populations, although the review aimed to be broader than just these populations. Although some studies, such as those included in Wright et al. (2023), explored well-evidenced interventions aimed at promoting attachment security, the study populations were considered ‘at risk’ of developmental trauma, rather than specifically aimed at treating developmental trauma symptoms, and as such were not included in the review.

Scoping searches established that literature prior to 2008 included studies on ‘attachment therapies’, an intervention practiced primarily in the United States that included restraint practices and was deemed to be coercive and dangerous (Chaffin et al. 2006). Following a White Paper in 2007, such therapies and practices were opposed, and newer techniques were promoted, which included attunement, sensitivity and regulation (Zeanah et al. 2011). This review therefore focusses on studies published from 2008 onwards.

Mixed methods studies were included if the qualitative element of the studies pertained to experience of the intervention. The quantitative elements of mixed methods studies did not relate to experience and are not reported.

2.3 Quality Assessment

Studies consisted of qualitative and mixed methods research that necessitated the use of two quality assessment frameworks: the Critical Appraisal Skills Programme (CASP), which is widely used in health-related qualitative evidence synthesis and endorsed by the Cochrane Qualitative and Implementation Methods Group (Long et al. 2020), and the Mixed Methods Appraisal Tool (MMAT) (Pace et al. 2012; Pluye et al. 2009).

As there is a paucity of studies on this topic, no studies were excluded based on quality assessment; however, quality was considered in the interpretation of results.

2.4 Data Extraction

Search results from the databases were combined (N = 3955), and duplicates removed using Covidence software (N = 1402). During the study selection process, two studies (Hewitt et al. 2018; Selwyn et al. 2016) used the same data set and presented the same results. In line with best practice guidance (Cochrane Information Retrieval Methods Group 2022), they were considered as one paper for the purposes of data extraction, and only the most recent paper was included in the review. These were manually marked as duplicates in Covidence.

Two reviewers screened study titles and abstracts for inclusion in the review (Cohen's kappa 0.58). Studies that clearly did not meet the inclusion criteria were excluded (N = 2426). Reviewers met together to discuss articles where it was less clear if they met the inclusion criteria to decide if a study should be included in the review. The full text of the remaining articles (N = 123) were assessed for eligibility by the author.

2.5 Synthesis Method

It was anticipated that the included studies would represent a heterogeneity and diversity of study design. Therefore, a qualitative systematic review approach was considered appropriate to analyse the results of the review. Synthesis was informed by Popay et al.'s (2006) framework and focussed on exploring relationships between studies and developing a robust synthesis through critical appraisal.

3 Results

3.1 Study Selection

Figure 1 presents a flow chart of search results and PRISMA screening process (Page et al. 2021).

3.2 Study Characteristics

Table 3 provides an overview of the study characteristics, methodologies and a summary of findings. The sample featured nine qualitative methods and six mixed methods designs. Studies were conducted across a range of locations, predominantly the United Kingdom (N = 9) and the United States (N = 4), as well as Canada (N = 1) and New Zealand (N = 1). Purposive sampling was used for all studies (N = 15). Qualitative data were collected through semi-structured interviews (N = 9), focus groups (N = 2) or both (N = 2) and a questionnaire (N = 1). One study (Carnes-Holt 2012) did not state how data were collected but referred to it as ‘feedback’. A range of analytical methods were deployed including thematic analysis (N = 6), interpretive phenomenological analysis (IPA) (N = 4), grounded theory (N = 1), content analysis (N = 1) and not stated (N = 3) but were indicative of thematic analysis.

A range of interventions and practice models were explored in the studies with some studies reviewing group-level interventions (N = 10) and others reviewing family-level interventions (N = 5). Of the group-level interventions, N = 3 involved caregivers and children together, and N = 7 were caregiver focussed. The underpinning theory for most of the interventions was attachment theory (Bowlby 1969) (N = 14) or other closely related theories of early child development (Winnicott 1960; Woods 2013) (N = 1). Some studies explored applications of established therapeutic models including dyadic developmental psychotherapy (DDP) (N = 5), filial therapy (N = 3), child–caregiver relationship therapy (CPRT) (N = 3) and mentalization-based therapy (MBT) (N = 1). McCullough et al. (2016) presented an integrative wrap around multidisciplinary approach, which is neuro-sequential and attachment focussed.

Most studies explored interventions aimed at adoptive or foster families. Puckering et al. (2011) was the only study to include birth families in a mixed sample with adoptive and foster families. Whitehead et al. (2023) was the only study to include kinship carers in a sample with foster carers. Donald and Ceballos (2020) explored experiences of residential care workers, and Turner-Halliday et al.'s (2014) paper drew from a sample of therapists and service providers to explore their experiences of DDP as part of a feasibility study. Swan et al.'s (2022) study focussed on reasons for self-referral to CPRT in a cohort of adoptive parents. There were no studies that explored or considered children and young people's experiences of the interventions, although one young person was included in an interview with their caregiver in Midgley et al.'s (2018) paper exploring MBT for adoptive families.

There was a vast difference in the length of the interventions that were explored ranging from six sessions (Holmes and Silver 2010; Midgley et al. 2018) to up to 5 years (McCullough et al. 2016).

3.3 Assessing Study Quality

Six qualitative studies met quality criteria, of which the remaining four did not explicitly state how they considered the relationship between the researcher and participants. The Carnes-Holt (2012) paper was presented as a discussion paper, rather than empirically collected research. Methodology was therefore not clearly defined and discussed. Although it was not presented as formal research, the caregiver feedback included was valuable in illustrating the experience of those who had attended the groups.

Three of the mixed methods studies did not describe clear rationale for design; however, many were exploratory studies of new interventions or adaptations and therefore appropriate to mixed methods design. For the mixed methods studies, the qualitative accounts of participants experiences converged with the quantitative outcomes.

There were limitations to some of the studies with low participant numbers, often focussing on one setting, reducing replicability and rigour. These limitations may reflect challenges in accessing research resources to conduct studies across a range of settings or groups. Most interventions explored could be considered innovative and developing in their evidence base. Smaller, service-based studies were therefore congruent with the research stage of the interventions.

4 Synthesis of Findings

Synthesis was informed by Popay et al.'s (2006) framework and guidance from Siddaway et al. (2019) and Baumeister and Leary (1997). Studies were tabulated to provide an overview (Table 3). To explore relationships between studies, the results sections of each paper were coded line by line in NVivo software. Discussion sections were coded, clearly marked as second order data and used to aid sense making of the findings. Central and recurring concepts were identified and grouped into codes. Through exploration of codes, the main concepts were identified. The research team supported the first author in this process through discussion of the findings and development of themes across studies. The results could be conceptualized into five interrelated themes as follows:

• Theme 1)

  Group processes in relation to the group interventions.

• Theme 2)

  Therapeutic alliance with the therapist or facilitator.

• Theme 3)

  Impact on carer.

  1. New understandings for caregivers of their child's feelings and behaviour.

  2. Changes in the carer.

• Theme 4)

  Positive relational change and family stability.

• Theme 5)

  Changes in the child.

4.1 Theme 1: Group Processes

Within the group interventions, participants spoke about the benefits of group dynamics (1; 2, 3; 4, 5, 6, 7, 10, 11, 13). Participants noted the validation and normalization of being with other people with similar experiences and struggles, giving them a sense of community where they felt safe to share their experiences openly and there was shared learning. One participant from the Ashton et al. (2017, 17) reflected on their group experience saying.

It takes a village. That's what that is. We all work together, and we all talk to each other and work through it.

The ‘Rebuilding Relationships’ study (10) was the only intervention that included birth mothers in a combined group with foster and adoptive mothers. The study purported that the group had a positive effect on the birth mothers' mental health, providing opportunities to reflect on early relationships and increase social support and networking.

CASA's Trauma and Attachment Group (1) included young people. Although only the caregivers were interviewed in the study, they spoke of some of the benefits for their children from the presence of other caring adults in the group. Conversely, in the Parent and Toddler Group (3), which was held online, caregivers were surprised that their children formed connections with other children in the group; however, some participants felt the children would have gained more benefit had the group been face to face.

The length of group interventions ranged from 6 to 18 weeks. Participants expressed a wish for groups to continue, or for the sessions to be longer, suggesting follow-on sessions or annual get-togethers (i.e., 6 and 13). This may speak to the value of connection with others with similar experiences and the potentially isolating experience of caregiving for a child with developmental trauma, as expressed by a participant in the Laybourne et al. (2018, 71) study.

To hear the difficult experiences of other carers and know that you are not the only one helped me a lot.

Three studies suggested that due to positive group dynamics, groups could offer benefits that family-level clinical support could not (3, 7, 13). Although there were indications that group-level interventions may augment treatment, they might not be able to replace direct family-level interventions. Some participants indicated that more targeted support for their child's behaviour or mental health was needed, viewing the group intervention as being part of the larger support system they required (13).

4.2 Theme 2: Therapeutic Alliance With the Therapist or Facilitator

Across 12 reviewed papers (1, 3, 4, 5, 6, 7, 8, 9, 12, 13, 14, 15.), the relationship and skills of the therapist or facilitator were highlighted as an important element of the therapeutic experience. This was the case for both family-level interventions and groups. This sentiment was expressed by the young person who was interviewed with her father in Midgley et al.'s (2018, 28) paper on a mentalization-based approach for adoptive families:

[The therapist] was listening to everything I was saying, and taking me into consideration … I felt that I could talk to people here.

Participants described how they experienced the facilitators as crucial for creating a safe and non-judgemental atmosphere in which group members felt contained, as described by a participant in Hewitt et al.'s (2018, 447) exploration of the Nurturing Attachments Group programme:

X was a fantastic moderator … without appearing to do anything, but I know she was doing stuff, she … totally stopped there being any sense of judgement against anybody about what they were saying about the way they had reacted to their children … she made the atmosphere such that nobody felt judgemental.

Some caregivers spoke about how the safety of this relationship reduced feelings of guilt and the need to be a perfect caregiver. It provided the opportunity for them to reflect on their own feelings and responses and engage freely in the therapeutic process. In addition to a non-judgemental stance, other attributes were appreciated such as the expertise and skill of the therapist. Caregivers in two studies appreciated the therapist/facilitator's appropriate use of humour and playfulness (7, 15). In Wingfield and Gurney-Smith's (2019, 12) study, one participant described how his therapists' ability to make sessions playful supported his daughter to feel less guarded:

Tina was quite skilled at pitching it at a level that Eloise would not find too threatening because, of course, if someone's defended the last thing you want to do is challenge that defendedness too early. So, she was very good at making it um, including sort of playing of games and making it fun really and Eloise responded to that.

Turner-Halliday et al. (2014) interviewed DDP therapists who also spoke about the importance of the therapeutic alliance. They viewed their role as facilitating the relationships with the caregiver and child, deepening their interactions. They explained how they might talk out loud with the child and the caregiver about what is happening between them, providing an opportunity to reflect and problem solve in real time. Ashton et al.'s (2017, 16) study suggested that a thriving facilitator/caregiver relationship provided ‘opportunities for healing beyond the walls of the therapeutic milieu’.

Clear expectations and communications from therapists and facilitators were considered important prior to the interventions. For instance, adoptive caregivers in the Di Lorenzo et al. (2023) paper spoke of the importance of managing their expectations through greater clarity around the intervention aims. Some families waited a long time for interventions or had experienced interventions that had failed them and may have little choice around which intervention is offered to them. This highlights some vulnerability in making decisions about what support they need. As a caregiver in the Wingfield and Gurney (2019, 10) paper expressed.

We would have jumped off the Empire State Building if someone had told us it would have worked for them.

4.3 Theme 3: Impact on the Carer

4.3.1 Subtheme 3a: New Understandings for Caregivers of Their Child's Feelings and Behaviour

There was convergence across all studies relating to themes of growth in understanding for caregivers. This theme sits within the context of the first two themes that highlight the importance of a safe and accepting therapeutic milieu to create this opportunity for change. Caregivers reported increased insight into the neurodevelopmental impact of their child's trauma and early adversity, creating newfound awareness. This created a shift in how they understood their children's behaviour, with authors in Ashton et al. (2017, 17) describing this as a shift from ‘my child is giving me a hard time’ to ‘my child is having a hard time’.

All the interventions were underpinned by theories of attachment and child development. These theoretical concepts were experienced as important in framing children's behaviour through a lens of early adversity. Participants in the Laybourne et al. (2008, 69) study expressed the importance of thinking about early attachment experiences, enabling them to recognize and understand current patterns in how their children interact and communicate.

I had not really thought about attachment much before. But now I know how important all interactions are from the point the child is born and the effect that not experiencing safety, security and comfort can have on a child.

For participants in 7 studies (3, 5, 6, 7, 12, 13, 15), the acquisition of new insights and understandings led to a greater capacity to remain present when their children expressed their emotional experiences. As a caregiver in the Midgley et al., (2018, 31) study described.

We are conscious of what we are doing, and that attachment is more present. Because sometimes thinking, ‘Oh, we are just parenting a normal child or a biological child who had not experienced trauma’. And so to think and have that in our minds is, well, was really helpful […] and keeping all the things she said in mind about attachment and interaction. What he seeks, why he seeks and how early trauma may affect him.

4.3.2 Subtheme 3b: Changes in the Carer

It seems logical that these shifts in caregiver perspective led to changes both in how they felt as carers and in how they responded to their children. Caregivers in seven studies reported improvements in their capacity to remain emotionally regulated whilst parenting their children (3, 5, 6, 7, 9, 10, 15). This improvement in emotional regulation may have been enabled due to a reduction of caregiver shame through the experience of the safe, non-judgemental therapeutic milieu, ameliorating their distress. Caregivers were less likely to blame themselves for the difficulties their child was experiencing. The authors in Hewitt et al. (2018) suggested that caregivers improved ability to regulate and manage their own emotions was a potential site for change, allowing caregivers to be more responsive and available for their child, therefore improving the quality of the relationship.

Seven studies referred to the role of caregiver stress in parenting children with symptoms of developmental trauma (3, 5, 7, 8, 10, 13, 15). A caregiver in the Laybourne et al. (2008) study referred to how new understandings of attachment issues and support emanated from knowing others in the group were managing similar behaviours. This reduced the stress in the relationship with their children and the personal stress of parenting a child with developmental trauma.

It is possible that the therapeutic space provided by the interventions, alongside positive changes in the carer's understanding, stress, shame and emotional regulation, allowed carers to pause and reflect on their child's behaviour and their own responses to it. Ten papers referred to caregivers' increased capacity for mentalization or reflective functioning, with carers developing a greater understanding of themselves and their children, supporting them to navigate the complexity of their relationships with their children (1, 3, 4, 5, 6, 7, 9, 12, 13, 15).

Eleven studies highlighted increased skills and a greater sense of confidence in the parenting task (2, 3, 4, 5, 6, 7, 10, 12, 13, 14, 15). These skills included attunement, empathy, curiosity, acceptance and emotional regulation. Whitehead et al. (2023) explored longer term outcomes and found that although caregivers reported an increase in confidence after they completed the programme, some reported confidence waned or fluctuated over the next 13–15 months. This speaks to the need for ongoing support to maintain progress.

Some participant's reported feeling more connected to their children (4, 5, 6, 7, 15). Residential workers in the Donald and Ceballos (2020) paper reported feeling more invested in their role with the child of focus, experiencing moments of connection and closeness.

4.4 Theme 4: Positive Relational Change and Family Stability

Study findings gave a sense that the initial impact of the interventions was on the caregivers as they gained new understandings and developed in their attitude, skills and behaviour. Indeed, many interventions were explicit in their aim of supporting therapeutic caregiving. It is then logical that relational change may follow and this was reported in 12 of the papers (1, 2, 3, 4, 5, 6, 7, 8, 12, 13, 14, 15).

The Turner-Halliday et al. (2014) study explored therapists experiences who referenced their hopes for therapy, believing small changes make a difference in the relationship. For instance, a child feeling able to bring an emotion into the room and accept some comfort from the carer signifies little steps that represent a slight shift in the relationship.

Participants across five studies attributed some of the changes in the relationship to experiences and interactions in between sessions, informed by the intervention (1, 3, 4, 5, 15). A participant in the Di-Lorenzo (2023, 238) study reflected on the impact of the intervention, realizing that ‘the work was going on between the sessions if you will, as we internalised it and worked with the kids’.

Participants in five studies (3, 4, 7, 12, 13) described how important relational changes were in strengthening the stability of the placement. In a residential setting, Donald and Ceballos (2020) suggested that systemic change could be created by increasing children's access to emotionally responsive adults and models such as CPRT could be helpful in maximizing residential workers' impact on children's mental health, given the limits on their time and encroachment of other duties. Participants in the Laybourne et al. (2008, 17) study went as far as to say that the intervention was significant in preventing family breakdown:

If I had not had the training, I feel that I would have failed the little boy I have now because the placement would have broken down. His behaviour was putting such a strain on our family and I just could not see a way out apart from him leaving. The training has changed my outlook.

4.5 Theme 5: Changes in the Child

Although this SLR focusses on experience and not efficacy, participants spoke qualitatively about changes they noticed in their children. This was the case not just for the interventions that included the children but also in two of the caregiver group interventions (6, 7).

Participants in the Holmes and Silver (2010) group intervention felt that children had become more responsive to their attempts to help, and communication was easier. The child interviewed as part of Midgley et al.'s (2018) study was able to identify that the therapy had helped her to think more about herself, understanding new aspects of her behaviour. She described how she had started to make sense of her mistrust in the context of her relational trauma. A caregiver in the Puckering et al. (2011) study noticed that their child responded well to the facilitators and peers who modelled positive behaviour.

Participants referred to specific benefits of the interventions for their children, including improved sleep, reduced separation anxiety, educational stability, improved emotional regulation, improved relationships with siblings and friends, increased openness, reduced shame and increased trust. Participants attributed behaviour change in the child to shifts in their understanding and parenting skills, as articulated by this participant from Laybourne et al. (2008, 72) who described feeling closer to him and the home feeling more harmonious as a result.

By understanding more about his controlling behaviour and different ways I can handle this, and by my showing empathy much more often, this has actually begun to change how the little boy expresses himself and behaves … I really feel I am starting to build an attachment with him and he is managing to fit in much more in the family home.

One caregiver in the Whitehead et al. (2023) study explained that through the intervention, she had learnt to pre-empt her child's difficult behaviour and apply new parenting skills. She felt this reduced her child's dysregulation over time. A therapist interviewed in the Turner-Halliday et al. (2014, 10) study suggested that:

Success is when a child is open to the relationship when they have an attachment need; so they signal their needs clearly.

Change in the child was not noticeable for all participants. This may speak to the ongoing challenges that many children with developmental trauma face. A caregiver in Hewitt et al. (2018) described cycles in their child's behaviour, with frequent changes in direction. In Donald and Ceballos's (2020) study, only one of the three residential workers was able to recognize qualitative improvements in behaviour. The possible explanation put forward for this by the authors was that the residential workers had become more attentive, noticing behaviours they did not initially notice. They also suggested that due to the high level of needs of children in residential care, a more intensive programme may be needed to create change. Carers in Whitehead et al. (2023, 145) discussed how after completing the programme, they became more accepting of their child and had developed a greater level of patience:

[Some of these behaviours] are probably never going to change and [I just need to] accept that this is the kid she is.

Puckering et al. (2011) acknowledged the complexity of needs for the children in their study, linking this to differences in the origin of their difficulties and other neurodevelopmental difficulties that could be contributing to the benefit children could receive from the intervention. Again, this highlights the need for ongoing support for many of these families rather than one-time interventions.

Behavioural change in the child may not be the main motivating factor in referral for interventions. When asked about the reasons for self-referral to a CPRT programme (Swan et al. 2022), child factors were the least responsible themes which prompted self-referral, with caregivers seeking to reduce their stress and develop new skills in repairing relationships with their children.

5 Discussion

This review suggests that caregiver–child psychotherapeutic interventions for developmental trauma symptoms were overall experienced positively and provided some benefit. Studies that interviewed caregivers who completed group interventions received feedback that suggested they were an important part of the offer, providing opportunities for normalization, connection and learning from others. Some of these caregivers suggested that groups may not be enough on their own and these participants provided clear rationales for needing family-level interventions.

Therapist skill and temperament were considered important in constructing a safe and non-judgemental therapeutic milieu creating a space for change and as such are congruent with current literature (Núñez et al. 2022). Participants referred to the support they experienced from the therapist/facilitator and how this reduced their feelings of shame and blame, enabling them to learn and develop new understandings of their children's presentations. New understandings were underpinned by relevant developmental theories, which supported carers to understand the emotional needs driving behaviours. Caregiver's reported reductions in stress and increased emotional regulation, which supported them to remain present to their children's needs, even in the tough times.

Changes in the child were more difficult to ascertain; indeed, for some studies, it was not within the aims to specifically prompt for this information. Nonetheless, some reported very clear benefits. This is difficult to make sense of given the heterogeneity of the studies. Interventions varied considerably in length, approach and modality. It is also important to consider individual differences in children and carers. Given these individual differences and the complex needs of children with developmental trauma, it is unlikely that there is a ‘one size fits all approach’; however, the papers did provide plentiful positive examples of perceived benefits of the treatments with general levels of satisfaction reportedly high. A conceptual map developed has been developed to illustrate relationships between the five themes (Figure 2).

5.1 Limitations

It is important to remember that the review pertains to experiences only and does not include other types of evidence for these approaches that may tell a different story. It may be limiting in that it could entirely omit interventions where there is not yet qualitative literature. It therefore cannot make bold and generalized claims, nor can it comment on the value of any specific model. Furthermore, the quality assessments identified some limitations in the scope of the studies with most of them representing smaller service-level pilot studies with low participant numbers. The decision to include studies that did not meet quality criteria reflects the paucity of research in this area but is also a significant limitation of the study design. The data may represent some biases due to the purposive sampling of the studies. Evidence may be derived from participants who were willing to share their experiences and may not be applicable to those who had fewer positive experiences or those who dropped out of the interventions. The findings of this review should therefore be considered with these limitations in mind. Notwithstanding these limitations, this is the first systematic review that critically examines experiences of caregiver–child psychotherapeutic treatment models for developmental trauma, and although reliable conclusions are limited, it adds a valuable contribution to the field.

5.2 Future Research

The review highlights important gaps in the literature. Many studies were at a service level, or small in nature. This highlights the need for robust, high-quality, qualitative studies that explore experience across settings and services that are independent of those settings and services.

The review also highlighted a limitation in the lack of studies that were retrospective, where participants could reflect on their experiences after a period of time had passed since the intervention. Only two papers considered this aspect (Whitehead et al. 2023; Wimmer et al. 2010). Given that review themes tentatively suggest that the mechanism for change may start in the carer's attitude, understanding, skills and stress levels, positive changes in the child's developmental trauma symptoms may take longer and may not be immediately apparent. Qualitative studies that explore the medium to longer impact of interventions on participants may be of value to this field of literature both to explore the longevity of any reported positive changes and to identify changes in developmental trauma symptoms that may take time to develop.

Finally, there was a lack of studies pertaining to the experience of the interventions for children and young people. Caregivers referred to their children's experiences, and in one study (Midgley et al. 2018), a young person joined their caregiver's interview; however, there were no studies exploring children's experiences directly.

5.3 Conclusions

To the best of our knowledge, this is the first systematic review that critically examines qualitative experiences of caregiver–child psychotherapeutic treatment models for developmental trauma, thereby making a valuable contribution to the evidence base. A comprehensive search strategy was developed, which facilitated access to a range of resources. Both the review protocol and the screening process were carried out in collaboration with others, reducing the risk of errors and biases. Notwithstanding this, this review is not without limitations.

The review highlights the potential value of caregiver–child focussed interventions for developmental trauma in supporting caregivers and strengthening the relationships. Further research into such experiences may be of value to the field, especially in understanding the mechanisms of how such interventions may be beneficial.