Evidence-base for the link between ACEs and long-term negative outcomes

ACEs can be broad in nature, and include mental/physical/sexual abuse, neglect, parental dysfunction/mental illness, or parental loss. There is strong evidence linking ACEs with long-term negative outcomes in areas such as mental health (Lereya et al., Reference Lereya, Winsper, Heron, Lewis, Gunnell, Fisher and Wolke2013; Geoffroy et al., Reference Geoffroy, Gunnell and Power2014; Mars et al., Reference Mars, Heron, Crane, Hawton, Kidger, Lewis, Macleod, Tilling and Gunnell2014; Jenkins et al., Reference Jenkins, Madigan, Arseneault, Rutter, Bishop, Pine, Scott, Stevenson, Taylor and Thapar2015) social functioning, occupational stability, living standard, wellbeing, physical health (Bellis et al., Reference Bellis, Hughes, Leckenby, Hardcastle, Perkins and Lowey2014; Holman et al., Reference Holman, Ports, Buchanan, Hawkins, Merrick, Metzler and Trivers2016) and risk of premature death (Brown et al., Reference Brown, Anda, Tiemeier, Felitti, Edwards, Croft and Giles2009). However, literature reviews highlight a lack of consistency and clarity concerning the definition, measurement and assessment of ACEs (McLaughlin, Reference McLaughlin2016). It is not always clear where the line is drawn between normative stress experiences and ACEs. There is also ambiguity as to whether low socioeconomic status (SES) should be considered a form of ACE, or an independent factor contributing to negative adult outcomes. Risk of exposure to ACEs may be more common in low SES environments (Hatch and Dohrenwend, Reference Hatch and Dohrenwend2007; Soares et al., Reference Soares, Howe, Matijasevich, Wehrmeister, Menezes and Gonçalves2016). Poverty is a powerful predictor of mental illness, and it predicts many other causes of mental distress (Read, Reference Read2010).

There are links between poverty, brain development and behaviour that suggest that children with low SES have a higher chance of behaving in ways that could harm their health, and reduce life expectancy. Evidence is emerging that our capacity to resist environments that tempt us to overeat, smoke, drink excessively, or be physically inactive is influenced by the strength of our ‘executive functioning’. Executive functioning skills (EFs) refer to the mental processes required when you have to pay attention, when going on ‘auto pilot’ would be ill-advised or insufficient. EFs are essential for mental health, physical health, and success; and for cognitive, social and psychological development (Diamond, Reference Diamond2013). Children living in low SES settings potentially face a double hit: living in environments that contain more cues for unhealthy behaviours, combined with exposure to psychosocial environments which may increase vulnerability to a reduction in the EFs to resist those cues (Stringhini et al., Reference Stringhini, Sabia, Shipley, Brunner, Nabi, Kivimaki and Singh-Manoux2010; Moffitt et al., Reference Moffitt, Arseneault, Belsky, Dickson, Hancox, Harrington, Houts, Poulton, Roberts, Ross, Sears, Thomson and Caspi2011). Further research is required to examine the roles of emotional processing and EFs in linking ACEs with negative outcomes in adulthood (McLaughlin, Reference McLaughlin2016).

There are several different methods of measuring ACEs. Most require self or parent report and assess up to twenty factors, most often including: parental incarceration, domestic violence, household mental illness, familial suicide and household alcohol or substance abuse. The methods usually use numeric, cumulative risk scoring methodology (Bethell et al., Reference Bethell, Carle, Hudziak, Gombojav, Powers, Wade and Braveman2017a). The same review suggests that research into a single standardised ACE measuring method would help accurately evaluate the link between ACEs and long-term outcomes.

Many studies in this area of research are relatively small, not population based and retrospective, which presents challenges for the evidence base as they are difficult to validate. Adults’ recollection of childhood experiences can be biased by their subsequent health and wellbeing (Reuben et al., Reference Reuben, Moffitt, Caspi, Belsky, Harrington, Schroeder, Hogan, Ramrakha, Poulton and Danese2016). Prospective studies provide the strongest data but the number of such studies is limited and fixed by the specific cultural and social context of the period in which they were carried out. Further research is required to address aspects of this field, such as whether particular sensitive periods exist for first exposure to ACEs during childhood. Some studies suggest that early-childhood exposure increases risk of negative adult outcomes including increased susceptibility to mental health problems (Sheridan et al., Reference Sheridan, Fox, Zeanah, McLaughlin and Nelson2012), other studies suggest that the time of first exposure has no influence on particular outcomes, such as suicide risk (Gomez et al., Reference Gomez, Tse, Wang, Turner, Millner, Nock and Dunn2017). It is still unclear how protective and resilience factors influence whether an individual will develop negative outcomes in adulthood. Little information exists that allows us to predict which children will do well and remain resilient and which will develop negative outcomes after being exposed to ACEs. These gaps limit the ability to decide the best ways to encourage development of resilience in exposed children, or whether it would be better to strengthen their capacity to cope with stressors.

The biological pathways and the developmental mechanisms involved linking ACEs to adult outcomes remain poorly understood. The degree to which negative outcomes are mediated through either continued adversity, or through the ACE being embedded within behavioural, neuropsychological, immune, neuroendocrine or epigenetic change needs to be determined. Mechanisms which are being investigated and requiring further research include epigenetic changes (Vaiserman, Reference Vaiserman2015), neurobiological effects (McCrory et al., Reference McCrory, Gerin and Viding2017) and other biological correlates (Danese and McEwen, Reference Danese and McEwen2012), including changes in the biological stress response (Kalmakis and Chandler, Reference Kalmakis and Chandler2015).

Physical health outcomes warrant further research to understand the mechanisms linking them with ACEs; these include cancer (Holman et al., Reference Holman, Ports, Buchanan, Hawkins, Merrick, Metzler and Trivers2016), diabetes (Huang et al., Reference Huang, Yan, Shan, Chen, Li, Luo, Gao, Hao and Liu2015; Huffhines et al., Reference Huffhines, Noser and Patton2016), chronic pain (Nelson et al., Reference Nelson, Cunningham and Kashikar-Zuck2017) and post-traumatic growth phenomena (Sapienza and Masten, Reference Sapienza and Masten2011). The mechanisms underlying poor mental health and wellbeing following ACEs need further investigation, including substance abuse vulnerability (Somaini et al., Reference Somaini, Donnini, Manfredini, Raggi, Saracino, Gerra, Amore, Leonardi, Serpelloni and Gerra2011), suicide (Sachs-Ericsson et al., Reference Sachs-Ericsson, Rushing, Stanley and Sheffler2016), intimate partner violence (Montalvo-Liendo et al., Reference Montalvo-Liendo, Fredland, McFarlane, Lui, Koci and Nava2015), psychosis (Dvir et al., Reference Dvir, Denietolis and Frazier2013), and homelessness (Davies and Allen, Reference Davies and Allen2017).

Screening that can identify children affected by ACEs needs additional research (Finkelhor, Reference Finkelhor2017), in conjunction with an improved understanding of the accuracy of ACE self-report, which can entail a risk of false-negative reports (Hardt and Rutter, Reference Hardt and Rutter2004; Anda et al., Reference Anda, Butchart, Fellitti and Brown2010). Many studies are not population-based, making studies small and potentially biased. There are few studies which address ACE risk in particular groups (for example, BME communities or high-risk subgroups such as multiply deprived children living with serious parental mental illnesses). There is also a lack of studies evaluating the outcomes of ACE exposure in developing countries (Sapienza and Masten, Reference Sapienza and Masten2011).

It is likely that different types of ACE create risk for adulthood in varying ways but there is a lack of clarity in this area. Literature has highlighted this problem and prioritises future research that can tease out the effects of particular types of ACEs on different outcomes (Humphreys and Zeanah, Reference Humphreys and Zeanah2015; McLaughlin, Reference McLaughlin2016). For example, one systematic review reported associations between physical abuse and psychological abuse and any type of cancer, and an association between sexual abuse with specific types of cancer. However, the same review also identified two studies that reported no association between physical and sexual abuse and cancer (Holman et al., Reference Holman, Ports, Buchanan, Hawkins, Merrick, Metzler and Trivers2016). Another systematic review comparing the relationship between different types of ACEs and diabetes reported that parental neglect had the strongest influence, while physical abuse had the weakest influence on later risk of developing diabetes (Huang et al., Reference Huang, Yan, Shan, Chen, Li, Luo, Gao, Hao and Liu2015).

Long-term adversity appears to be more damaging than single events. Many children are not exposed to just one type of ACE – adversity is often experienced in the context of a so-called broader ‘risky environment’ (Cicchetti and Toth, Reference Cicchetti and Toth2005). For example, poverty and parental substance dependence are linked to child deprivation, neglect and a lack of exposure to resilience factors. Chronic exposure to ACEs predicts the greatest negative outcomes in general (Anda et al., Reference Anda, Butchart, Fellitti and Brown2010; Danese and McEwen, Reference Danese and McEwen2012) with an increased risk for multiple negative outcomes including for psychosis (Dvir et al., Reference Dvir, Denietolis and Frazier2013) and asthma (Exley et al., Reference Exley, Norman and Hyland2015). Different people react differently to the same ACEs, leading to a range of outcomes in exposed individuals. Further research is required to understand the reasons for individual differences following ACE exposure, including but not limited to research into resilience and vulnerability (McLaughlin, Reference McLaughlin2016; Traub and Boynton-Jarrett, Reference Traub and Boynton-Jarrett2017) as well as the effects of culture (Sapienza and Masten, Reference Sapienza and Masten2011), ethnicity and gender (Kajeepeta et al., Reference Kajeepeta, Gelaye, Jackson and Williams2015), and mediating factors (Kalmakis and Chandler, Reference Kalmakis and Chandler2015) including cognitive risk factors (Liu et al., Reference Liu, Atrooz, Salvi and Salim2017).

Quality of the evidence-base for early-years interventions

A review examining the evidence base for youth interventions lists twenty-seven broadly psychotherapeutic programmes that are relevant and recognised as ‘well established’ or ‘probably efficacious’ and can be considered as evidence-based psychotherapies (Weisz et al., Reference Weisz, Ng, Lau, Rutter, Bishop, Pine, Scott, Stevenson, Taylor and Thapar2015). Overall, there is a lack of evidence-based interventions (Bryson et al., Reference Bryson, Gauvin, Jamieson, Rathgeber, Faulkner-Gibson, Bell, Davidson, Russel and Burke2017), and few for certain populations. Many population groups need particular attention, including children in foster care (Hambrick et al., Reference Hambrick, Oppenheim-Weller, N’zi and Taussig2016), children at risk of suicide (Sachs-Ericsson et al., Reference Sachs-Ericsson, Rushing, Stanley and Sheffler2016), those experiencing intimate partner violence in the family (Montalvo-Liendo et al., Reference Montalvo-Liendo, Fredland, McFarlane, Lui, Koci and Nava2015), children of obese women (McDonnell and Garbers, Reference McDonnell and Garbers2017), ethnic minorities (Burnette and Figley, Reference Burnette and Figley2017), children with co-morbid psychosis (Dvir et al., Reference Dvir, Denietolis and Frazier2013), and young people experiencing homelessness (Davies and Allen, Reference Davies and Allen2017).

It has also been suggested that we need to develop different interventions for different settings, such as those focused on families (Figley and Burnette, Reference Figley and Burnette2017), those with a whole community focus (Bethell et al., Reference Bethell, Solloway, Guinosso, Hassink, Srivastav, Ford and Simpson2017b) and interventions that may be used in primary care (Bransford and Blizard, Reference Bransford and Blizard2016) as well as in psychiatric and residential treatment services (Bryson et al., Reference Bryson, Gauvin, Jamieson, Rathgeber, Faulkner-Gibson, Bell, Davidson, Russel and Burke2017). Further evidence needs to be gathered on how to engage families in interventions and the value of doing so (Bethell et al., Reference Bethell, Solloway, Guinosso, Hassink, Srivastav, Ford and Simpson2017b). We need to understand the barriers to implementing trauma informed care (TIC) and how sustainable changes in practice are following TIC training (Wilson et al., Reference Wilson, Hutchinson and Hurley2017). TIC is a concept developed in the US to address the fact that many people in contact with mental health services have experienced trauma and to avoid staff practices in mental healthcare re-traumatising these people: for example, by pressuring a patient to accept medication which mimics previous experiences of powerlessness (Sweeney et al., Reference Sweeney, Clement, Filson and Kennedy2016). Finally, the feedback and perception of those who use mental health services and interventions need to be collected to better understand any issues regarding the mental health service experience and existing barriers to asking about childhood abuse (Read et al., Reference Read, Harper, Tucker and Kennedy2018).

Literature reviews suggest that the outcomes of interventions need better evaluation (Bethell et al., Reference Bethell, Solloway, Guinosso, Hassink, Srivastav, Ford and Simpson2017b). To be able to apply interventions effectively, further research, development and evaluation of particular approaches and interventions is necessary for ACE screening tools/approaches (Finkelhor, Reference Finkelhor2017), preventative interventions (Mayer and Thursby, Reference Mayer and Thursby2012; Larkin et al., Reference Larkin, Felitti and Anda2014), trauma informed educational approaches (Brunzell et al., Reference Brunzell, Stokes and Waters2016; Wiest-Stevenson and Lee, Reference Wiest-Stevenson and Lee2016) and TIC approaches (Oral et al., Reference Oral, Ramirez, Coohey, Nakada, Walz, Kuntz, Benoit and Peek-Asa2016; Bryson et al., Reference Bryson, Gauvin, Jamieson, Rathgeber, Faulkner-Gibson, Bell, Davidson, Russel and Burke2017). Reviews highlight the need for more information on the overall costs of assessing and addressing ACEs (Bethell et al., Reference Bethell, Solloway, Guinosso, Hassink, Srivastav, Ford and Simpson2017b), cost-benefit analyses (Finkelhor, Reference Finkelhor2017), measures of costs saved (Mayer and Thursby, Reference Mayer and Thursby2012) and cost-effectiveness (Larkin et al., Reference Larkin, Shields and Anda2012). Research shows that the evidence base for many parent/family interventions aimed at improving parenting ability and child outcomes is relatively poor and therefore suggests that interventions must be appropriately targeted for optimal effect (Juffer et al., Reference Juffer, Bakermans-Kranenburg and van IJzendoorn2005). In particular it is increasingly understood that the most vulnerable or most at risk children are also the most sensitive to intervention. Intervention personalisation, where interventions are tailored to the individual child, the individual family and age or developmental stage, may be important and necessary. Not all interventions are good for all children. More understanding of the optimal timing of an intervention is needed, in terms of how the intervention interacts with child experiences and characteristics (Hambrick et al., Reference Hambrick, Oppenheim-Weller, N’zi and Taussig2016), and possible sensitive periods during development (Huang et al., Reference Huang, Yan, Shan, Chen, Li, Luo, Gao, Hao and Liu2015; McCrory et al., Reference McCrory, Gerin and Viding2017).

Local and national government policies for early-years interventions

It is claimed that evidence-based intervention programmes are little used in practice (Weisz et al., Reference Weisz, Ng, Lau, Rutter, Bishop, Pine, Scott, Stevenson, Taylor and Thapar2015). Some practitioners may prefer nondirective styles of intervention that are not evidence-based but rather have ideological backing. The programmes can appear too tightly organised and lead to a lack of motivation for the young patient or the therapist. There is also a lack of dissemination of new and developing interventions to those commissioning or delivering services. One 2016 review of TIC approaches mentioned the US as the only nation to have a national policy related to trauma (Sweeney et al., Reference Sweeney, Clement, Filson and Kennedy2016). The same review describes TIC approaches as only beginning to reach the UK and having had little impact in the UK so far, even though there is evidence that TIC systems are effective and can benefit both staff and those receiving mental healthcare, at least in the short term. ACEs and trauma awareness were included in Scotland’s Mental Health Strategy (2017–2027) (Scottish Government, 2017) and the Scottish government commissioned NHS Education for Scotland to develop a National Trauma Skills and Knowledge Framework and a National Training Plan for practitioners. Strategy documents on gender sensitive services that included trauma awareness were published by the Department of Health (Golding and Duggal, Reference Golding and Duggal2011). The Department of Health also made recommendations in 2003 that made enquiry about abuse compulsory in mental health settings, and initiated a programme aimed at training staff (Department of Health, 2003). However, there is little evidence that trauma enquiry occurs in routine practice. Updates to the National Institute for Health and Clinical Excellence guidelines, such as to the guidance for the management of schizophrenia (NICE, 2014), may help prompt TIC being adopted. One review lists a number of barriers to implementation of TIC, including resistance by practitioners to the causal link between trauma and ACE to later risk of psychosis and mental distress, and the fact that continuous change to UK public services leads many to be wary of new initiatives (NICE, 2014).

Poor dissemination and a lack of accessibility and visibility of research represent challenges to the implementation of new evidence-based practice. One review of the assessment and response to ACEs highlighted a lack of awareness of new research and care strategies by nursing staff, who form the largest proportion of frontline healthcare staff (Waite et al., Reference Waite, Gerrity and Arango2010).

Future priorities

The UK Research Councils recognise that this research into ACEs and their implications requires additional funding. This is particularly true for mental health; several funding bodies are highlighting the relevance of early life experience (e.g. 2017 Medical Research Council mental health strategy, Medical Research Council, 2017). Funding mechanisms are designed to create competition between expert groups and universities rather than collaboration where groups with common or overlapping expertise are drawn together. Public and third sector funding bodies put out researcher-led or themed calls – however, there may be little input from stakeholders or affected groups. There is a corresponding limitation in the effective setting of research priorities on a national basis. The James Lind Alliance (JLA) is an example of a mechanism that allows ‘Priority Setting Partnerships’ to be established with the aim of bringing patients, carers and clinicians together to identify research priorities (www.jla.nihr.ac.uk/jla-guidebook/chapter-3/prioritysetting-partnerships.htm). There is need for better coordination between research about ACEs and associated outcomes including mechanisms and research on the effectiveness of interventions, which is separately funded.

Much of the scientific research in this field is fragmented and focused on specific health or social outcomes, without being more widely framed. There is an urgent need for rigorous reviews of the evidence concerning ACEs. NICE produces authoritative reviews on interventions for individual disorders but is limited by its restriction to health and social care. This area was partly the key remit of the National Academy of Parenting Practitioners (NAPP) (Department for Education, 2012), which closed in 2010. The NAPP aimed to provide an understanding for commissioners and educators of the quality of the evidence base for the range of parenting interventions, monitor their use and co-ordinate the development of research projects and measures. The potential value of such a body remains. The model could be extended to include educational and primary care interventions. More work is needed to improve information sharing about children’s exposures to ACEs, as well as sharing and accessibility of evidence. NAPP recommended creating a ‘living’ evidence synthesis and dissemination mechanism to use existing dissemination platforms to ensure that information reaches those involved in children’s health services; using existing rapid-cycle learning platforms to maintain networks of families and professionals to promote cross-sector learning and engagement; and developing open-source training and tools (Bethell et al., Reference Bethell, Solloway, Guinosso, Hassink, Srivastav, Ford and Simpson2017b).

As highlighted above, there is a need for improved coordination of research in this area in order to ensure children and young people living with adversity are at the heart of the process to help set priorities and programmes whereby evidence gaps are can be addressed. One mechanism may involve an expert commission able to develop a portfolio of research agreed by a representative panel of experts by experience alongside researchers crossing disciplinary boundaries, and setting out a series of agreed aims, priorities, milestones and outputs.