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Stress in adolescence and childhood is a common cause of mental health problems later in life.1 For example, early childhood stress permanently changes the expression of corticoid receptors and thus the reaction of the HPA axis to acute and chronic stress.2 A basic description of the effects of early childhood stress and its epigenetic manifestation can be found in Eckerle.3
Early childhood or chronic stress, including traumatic experiences, also plays a role in the development of ADHD. Children who experience early childhood trauma, such as maltreatment, sexual abuse, separation from caregivers, hostile parental behavior or war experiences, have an increased likelihood of developing ADHD symptoms. Conversely, studies show that ADHD sufferers have experienced a significantly higher number of traumatic events, particularly in the context of relationships.
Traumatizing experiences can permanently change the dopaminergic system in the brain and thus increase the risk of ADHD.
1. Early childhood or chronic stress as a risk for ADHD¶
Many children and adults with ADHD describe sexual abuse and/or trauma.4
A number of studies confirm a disproportionately high frequency of early trauma in ADHD sufferers compared to non-affected people.56789101112131415 The same applies to brain injury trauma and otorhinological trauma. There is debate as to whether causation is involved or whether the symptoms of ADHD and trauma overlap. Other sources describe early trauma more generally as a contributory cause of mental health problems.16171819202122
Early childhood stress (singular traumatic stress) and chronic stress are involved in the development of ADHD.23 A Swedish cohort study found that ADHD sufferers were 1.8 times more likely to experience traumatic life events than those without the disorder.24
20 % to 50 % of all children who experience early childhood trauma develop clinical ADHD symptoms.232526
Childhood maltreatment correlates with an increased risk of ADHD in adults.272829303132 Children with ADHD are more likely to be abused. One study found that girls with ADHD were three times more likely to be abused than girls without ADHD. , another study also found that children with ADHD were three times more likely to be abused, twice as likely to be physically abused and two and a half times as likely to be emotionally abused.333435
Child maltreatment, especially emotional maltreatment, also correlates with increased emotional dysregulation and reactivity.27
One study found a highly significant increase in the frequency of traumatic experiences in people with ADHD.36 The non-interpersonal events were barely increased, while the interpersonal events were massively increased compared to those not affected. More on this at ⇒ Trauma as a cause of ADHD.
Traumatizing experiences are intense stress experiences in the broader sense, e.g:
Frequent separation from the caregiver without replacement
Deprivation (emotionally poor relationship between parents and child)
Hostile / helpless behavior of the parents towards the child
Long-lasting couple conflicts / marital problems of the parents
War experiences
A study of kindergarten-age children of refugees from war-torn regions showed that they were more “fidgety”, had an enormous urge to move and found it harder to concentrate. At the same time, they were described as being so traumatized that a hot glue gun made them cry. 38
Shocks (e.g. noise shock)
One affected person reports
An ADHD-HI sufferer: My mom is definitely an ADHD-HI sufferer. Despite this, I always felt securely loved by my parents and my grandmother, who was my main caregiver. My family reports that I was a pure ray of sunshine as a baby (wish child): cheerful, slept well, everything was wonderful. Until I suffered a noise shock at the age of 2.5 (New Year’s Eve firecrackers right outside the bedroom window). My parents claim that I didn’t sleep at all for 3 months after that. Whether this is true or not - from this time onwards, according to their reports, I was exhausting and anxious. I would crawl under tables trembling, especially in front of jet fighters (which at that time were still breaking through the sound barrier and therefore making a huge bang). During thunderstorms at night, I fled to my parents’ bed in a panic until I was 12 or 14. Falling asleep was a drama for decades.
ADHD risk increases with the level of stress
The risk of children developing ADHD (odds ratio) increases with the level of psychosocial stress (Rutter indicator, RI). With an RI of 1, the odds ratio is 7; with an RI of 4, it is 41.7.39
Odds ratios > 1 indicate an increased risk. Disorganized attachment behavior is a risk element of ADHD.40 Attachment disorders in children in the first years of life lead to activation of the DRD4 gene, which is also common in ADHD, if there is a corresponding genetic disposition.41
Massive maternal stress in the first years of childhood causes significant epigenetic changes in the children’s DNA.42
Emotional abuse and physical abuse significantly increase the risk of ADHD and the symptoms of ADHD, as do unfavorable living conditions and school anxiety.43
A study of 110 boys found a highly significant increase in the frequency of traumatic experiences among ADHD sufferers.36
The Life Incidence of Traumatic Events (LITE-P) test asks:
Child involved in car accident
Child injured in another accident or in hospital
Nearby person injured
Family member in hospital
Death of a family member
Friend ill or died
Child experienced fire
Child experienced natural disaster
Mutual injury/destruction of things between adults
Separation / Divorce Parents
Maltreatment of the child
Child tied up / locked up
Abuse of the child
Child threatened
Child robbed
On average, the 65 boys with ADHD had experienced almost every type of trauma more frequently than the 45 boys in the comparison group. The interpersonal events (traumas in the relationship context) were significantly higher than the non-interpersonal events compared to those not affected. The number of relationship-relevant IPE traumas also correlates with the intensity of hyperactivity and overall symptoms. In terms of age, inattention symptoms also correlate highly significantly with the number of IPE traumas.
Several other studies have come to similar conclusions.4445
Trauma caused by emotional neglect or abuse significantly increased the likelihood of ADHD.46
In contrast, another study reported that victimizing trauma increased the likelihood of ODD, but not ADHD.47
Assuming that one third48 to half of all children and two thirds of all children in psychiatric samples have experienced trauma, a frequent overlap between ADHD and early childhood trauma is to be expected.49 However, this alone does not explain why the studies on trauma as a (co-)cause of ADHD predominantly found a higher number of early traumas in ADHD sufferers than in non-affected persons.50
One pathway for the development of ADHD is attributed to genetic causes in conjunction with environmental experiences, whereby these environmental experiences can be early traumas.51 A combination of a low-activity MAO-A gene variant, traumatic experiences in childhood and exposure to certain pollutants, which in turn reduce MAO-A expression, increases the risk of ADHD particularly strongly.52
Hypothesis on trauma as a cause of ADHD
Since ADHD correlates with a stimulus filter that is too wide open, which can be a consequence of stress dysregulation on the one hand, but can also be understood as a manifestation of the genetic disposition for ADHD (high sensitivity) on the other, the question arises as to whether the early childhood stress load that manifests ADHD cannot be understood as a low-threshold traumatization of highly sensitive natures. It can be assumed that early childhood multiple traumas can trigger ADHD if there is a corresponding genetic disposition. The more sensitive a person is, the lower the required impact of a threatening stress situation to neurologically implement a traumatizing manifestation of stress regulation dysfunction.
It is well known that different personality types react differently to environmental influences. Introverts react more intensely to environmental influences than extroverts.53 The concept of high sensitivity according to Aron is closely linked to introversion.
This raises the question of whether such low-threshold traumatization of those affected, which in the case of ADHD typically occurs in the first 6 years of life, is at all accessible to therapeutic interventions and analyses.
The
low memory capacity of people for events in the first years of life on the one hand and
the fact that even impacts far below what non-affected people would consider to be a serious cause of trauma can trigger a traumatizing reaction in genetically predisposed people,
could obscure the view of such a cause.
Following this idea, the principles of EMDR therapy, which is recognized as effective for trauma, could be transferable to ADHD.
In trauma and PTSD there is a partial overactivation of the PFC, which can be effectively reduced by the bilateral sensory contacts in EMDR, which also correlates with the extent to which PTSD symptoms are reduced.54
Children with ADHD are also more likely than average to be victims of violence and bullying (as a result of ADHD).55
2. Stressful experiences in childhood and early adolescence cause persistent ADHD in adulthood¶
A study of stress levels in children with ADHD found that high stress levels in childhood and adolescence were associated with severe ADHD-HI or ADHD-I progression into adulthood, while children with low stress levels in childhood and adolescence often showed remitting ADHD (ADHD-HI as well as ADHD-I).56
Even though it is not yet certain that (early childhood) trauma increases the risk of ADHD (causally) through changes in the dopaminergic system, there is strong evidence that trauma in early childhood and adolescence permanently alters the brain’s dopaminergic system.57585960 One mediator could be that stress alters the HPA axis, which in turn exerts an influence on dopamine synthesis and dopamine receptors.61
The most important dopaminergic nodes of the stress network in the brain are
Flattened dopamine stress response in the mPFC6667
Increased tonic dopamine levels in subcortical areas68
Increased noradrenaline release in response to acute stress66
Early childhood stress appears to cause an increased dopamine stress response in the striatum later in life6970
In humans, the dopaminergic system in most nodes of the stress network is primarily controlled by dopamine D2 and D3 receptors.717273
Trauma in childhood correlated positively with the availability of D2 receptors in men and in women.74
Early childhood trauma correlates with reduced levels of the dopamine breakdown product homovanillic acid in the blood plasma75 and in the cerebrospinal fluid76.
One study reports a correlation between the spatial extent of dopamine activity in the mPFC during acute stress and the severity of the stress experience in early or later childhood.77
