Dr Alan Meehan Hi, there. I’m Dr Alan Meehan,  and I’m a Lecturer in Psychology at the Institute   of Psychiatry, Psychology and Neuroscience  at King’s College London. So, in this video,   I’ll be answering several commonly asked questions  about this topic, across three key areas.   I’ll describe what ACEs are, and how experiencing  them can impact the health and development of   children and young people, discuss some of the  most common risk and protective factors for ACEs,   and outline some current issues within this  research field, including efforts to prevent   and treat the harmful effects of adversity  on young people’s health and wellbeing. Adverse childhood experiences, or ACEs for  short, is the term used to describe a series   of life events during childhoods, which  are linked to an increased risk for trauma,   as well as other negative consequences  for health and development. So,   ACEs include different forms of child  maltreatment, abuse and neglect, as well   as other potential sources of adversity  or trauma related to challenging family   circumstances that a child or a young person might  experience when growing up in their household. So, the original definition of ACEs was  established in a landmark study of adults   in the United States in the late 1990s,  in which participants were asked whether   they had experienced ten different categories  of adverse events before the age of 18. So,   these ten types of ACEs were usually  grouped into three main domains. The   first of these is abuse, and this  was defined in three different ways.   First was physical abuse, which refers to  situations where a caregiver, or another adult,   physically hurts the child, for example,  pushing, shoving, slapping or hitting them. Second was sexual abuse, which was defined  as “sexual contact by a caregiver or another   adult that is unwanted,” or where the child is  too young to understand what’s happening. And   then the third was emotional abuse, which  included circumstances where a caregiver   or other adult would swear at or threaten a  child, say hurtful things to them, or act in   any other way that may make the child afraid  that they will be physically hurt or injured. The second domain within this original  ten ACE framework relates to neglect,   and this is also separated into two components.  The first was physical neglect, which involves   situations where a child is left unsupervised when  they’re too young to care for themselves, or where   they don’t have access to necessary resources,  things like food, clothing, school supplies,   or medical treatment, for example. The second  form of neglect is emotional neglect, and this   is where a child does not receive sufficient  emotional support from people around them.   For example, situations where a child has no-one  to make them feel special or provide them with   strength and support, or tell them that they  believe in them or want them to succeed in life. The third and final domain in this ACE framework  is usually referred to as “household dysfunction,”   and this includes five key stressors that a  child may experience within their own family or   household growing up. And these are, witnessing  domestic violence or abuse, parental separation   or divorce due to relationship breakdown, and  having a close family member who either has   misused drugs or alcohol, has exhibited mental  health problems, or who served time in prison. Now, in the 25 years or so since  the ACE construct was first defined,   other Researchers have expanded this original  definition to incorporate other adverse   childhood experiences. And this has included  things like peer victimisation and bullying,   witnessing violence in one’s  local community or neighbourhood,   and broader social adversities, including  things like deprivation and discrimination. So, exactly how common are ACEs then?  Unfortunately, adverse childhood experiences are   fairly prevalent, whatever the exact events we use  to define it. So, a recent analysis of data from   over 200 studies of ACEs across 22 countries  found that 60% of adults, there and abouts,   reported that they have been exposed to at least  one ACE while growing up. And, furthermore,   around one in six adults report exposure to four  or more types of ACEs before the age of 18, and   this is typically used to represent high levels  of ACE exposure by Researchers in this field. Now, since the late 1990s, hundreds of research  studies have demonstrated that ACEs are   experienced by individuals in high, middle and  low income countries, and at all socioeconomic   levels of society. However, the prevalence of ACEs  is not evenly distributed across the population.   For example, high levels of ACEs are more  common among individuals from deprived and   lower socioeconomic backgrounds, from those with  a history of mental health problems or substance   abuse issues in families, and those whose own  parents experienced ACEs themselves. Also,   within many Western contexts, high rates of ACEs  has also been observed in individuals from Black,   Latinx, and indigenous backgrounds, compared  to White children, and related to that point,   it’s often been noted by these studies  that individuals in these groups often   experience historical, structural and  economic inequalities and discrimination,   which could potentially exacerbate or  perpetuate the negative consequences of ACEs. Finally, it’s commonly observed within  these prevalent studies that most ACEs   co-occur with one another, in that experiencing  one type of ACE typically puts an individual   at a significantly higher likelihood  of experiencing another. For example,   a child who experiences physical abuse is  at far greater risk of also experiencing   emotional or verbal abuse than a child  who’s not been physically abused. So, how is it that ACEs can affect our  development? Well, based on over 25 years   of evidence, it’s clear that experiencing  adversity during childhood is associated with   negative health and development outcomes across  the entire life course. So, in the original study   in which the concept of ACEs was first defined,  Researchers found that adults who reported   experiencing higher levels of childhood adversity  were more likely to present with a range of   mental health problems like depression, substance  abuse, and even suicidal thoughts and behaviours,   as well as physical health conditions, including  things like heart disease, diabetes and obesity. Now, since that original ACE study, there have  been hundreds of studies that have reported a   consistent link between experiencing more ACEs  and increased risk of unfavourable life outcomes,   up to and including reduced life expectancy and  even premature death. And, in these studies,   you tend to see a dose-response relationship,  so this means that as the number of ACEs a   person reports experiencing increases, so too  do the rates of various unfavourable outcomes. It’s also been proposed that ACEs can contribute  to mental and physical health problems indirectly,   through an increased likelihood of engaging in  what are known as health-harming behaviours. So,   this includes things like smoking, alcohol  and drug misuse, sexual risk taking,   and involvement in antisocial behaviour and  crime. Now all of these risky behaviours can   themselves lead to negative health outcomes and  limit an individual’s life opportunities. And,   in particular, when we think about studies of  adolescents and young adults, ACE exposure is   consistently linked with school suspension and  expulsion, lower educational attainment and,   ultimately, because of that, reduced  employment and life opportunities. So, what are some of the pathways to which these  ACEs might exert these negative effects on our   mental and our physical health? Now, in trying  to identify the ways by which ACEs influence our   development, research has mainly focused on both  psychological and physiological mechanisms. So,   starting with the psychological mechanisms then,  when we’re faced with a stressful or a challenging   situation, one way of dealing or coping with  it is to engage in what’s known as “cognitive   reappraisal,” and this involves changing how  we think about or appraise a given situation,   in such a way that we can change our feelings  or emotions around that event. So, in this way,   the – this individual appraisal can help  us to regulate the negative emotions we   may have about certain adverse experiences.  And studies have found that individuals who   have experienced childhood adversity often have  difficulty consciously recognising and correcting   those negative thought patterns in that way.  And this can make it more difficult for them   to regulate their negative emotions,  and may put them at increased risk for   symptoms of emotional and stress-related  disorders such as depression and anxiety. Now, exposure to childhood trauma can also alter  an individual’s ability to accurately appraise   or cope with threatening stimuli or stressful  life events. And this may lead them to rely on   short-term or potentially maladaptive coping  strategies, to deal with these life stressors,   and some of these may negatively affect their  health, for example, engaging in drug use. At the same time, though, there’s also evidence  to suggest that individuals who experience early   life adversity can show enhanced cognitive skills  in relation to coping with stressful or dangerous   stimuli. So, it might actually be  that it’s the ability to be flexible   in deploying different reappraisal  or emotion regulation strategies,   depending on the specific type of  stress of experience you’re faced with,   that might be protective against some  of the harmful effects of adversity. Moving then to the, kind of, physiological  mechanisms, Researchers have also tried to   identify how ACEs get under our skin, in  a sense, to influence physical health,   in particular. And from this work, the  concept of “toxic stress” has emerged,   to describe how ACEs can trigger  physiological and biological   reactions that can make us vulnerable to  a wide range of physical health problems. So, just to, kind of, explain this,  when we’re faced with a stressful event,   we experience a short-term, kind of, survival  response, which is often thought of as the   “fight or flight response.” So, specifically  in response to a stressful event, our bodies   release key hormones that help us to adapt to  the situation, such as cortisol and adrenaline,   and the release of these hormones has  number of physiological effects. It leads   to things such as an increased heartrate,  changes to our breathing and our vision,   and greater activation of key markers within  our central nervous and inflammation systems. Now, generally our physiological systems return  to normal levels soon after a given stressful   event has passed. However, if we’re exposed to  repeated or chronic stress, such as ACEs, this   can mean that we don’t experience this return to  normal levels, and this could lead to prolonged or   frequent activation of the stress response system.  So, you could think of this as similar to revving   up a car’s engine for days, or even weeks, at a  time without actually driving or going anywhere. So, that constant excessive activation  of our stress response systems,   due to this chronic ACE exposure,  is known as “toxic stress,”   and it can lead to long-lasting wear and  tear on the body, which can affect various   systems such as the immune system, the metabolic  system, and even the cardiovascular system. And,   also, if this prolonged stress response occurs  during influential periods of brain development,   it can become permanently ingrained as our default  response to any future stressful life events. So, overall then, there’s, kind of, consistent  evidence that changes to psychological and   physiological systems brought on by ACE  exposure can impair our cognitive and our social   development, thereby increasing our risk of worse  health later in life. However, a crucial point to   make here is that ACEs are not deterministic,  so that means that they don’t always lead to   poor outcomes in all cases. So, there’s always  significant individual differences in all of these   ACE-related outcomes and mechanisms, and many  children who experience ACEs go on to show similar   patterns of health and wellbeing later in life  as those who have not experienced any adversity. Also, when we consider all this evidence, it’s  important to note that the extent to which ACEs   increase a person’s risk for mental health  problems is still not totally clear, due to   what’s known as “confounding” with other genetic  and environmental factors. So, just as an example,   children who experience ACEs are likely to have  some family history of mental illness and, in   turn, because of that, have a higher genetic risk  for mental health problems in the first place. So,   therefore, it can be difficult to disentangle  the unique causal effects of adversity on health   in the future, and really there’s a need here for  more longitudinal studies, that can better account   for any confounding influences that might be at  play, as well as more rigorous, quasi-experimental   methods that will allow us to test and measure  the unique causal effects of adversity.