Causes of self-injurious behaviour in Cornelia de Lange Syndrome

Introduction

When thinking about self-injurious behaviour the word “cause” is itself problematic. There is almost never a one-to-one relationship between what we think of as a cause of self-injurious behaviour and the behaviour itself. It is better to think of factors that make the behaviour more or less likely to occur. It is also important when thinking about self-injurious behaviour in children and adults who have Cornelia to Lange Syndrome that a variety of factors are considered and that it is not assumed that the cause of selfinjurious behaviour at one time is necessarily the cause at a later date. There is very clear evidence that the causes of self-injurious behaviour differ between people and that they may change over time. Additionally, even if the form of self-injurious behaviour is similar for two people (e.g. they both bang their heads) it does not necessarily mean that it happens for the same reason. In this chapter we will consider the possible causes of self-injurious behaviour in Cornelia de Lange Syndrome, focussing first on internal causes and then moving on to external causes and then we will consider how these might interact at one point in time and over time.

Internal causes

It is useful to think about the causes of self-injury as being internal to the person, usually meaning things that we cannot see and external, things in the environment that seem to affect the behaviour. There are two types of internal causes, pain and discomfort and sensory stimulation, and we will describe these in turn.

Relief of pain or discomfort

It was noted in Chapter 3 that in people with intellectual disability, as well as those who do not have a disability, self-injurious behaviour can occur in response to painful medical conditions and discomfort. It was also noted in Chapter 2 that there are number of medical conditions in Cornelia de Lange Syndrome that can give rise to pain and discomfort. Whilst there is very limited research data on the relationship between pain and discomfort in Cornelia de Lange Syndrome and self-injurious behaviour, our clinical experience leads us to believe that this should always be considered first.

It is possible that the dental problems experienced by children adults with Cornelia de Lange Syndrome, such as decay associated with thin enamel, reflux and the crowding of teeth, will lead to discomfort. This may in turn lead to selfinjurious behaviour as the individual attempts to relieve the pain and discomfort by banging the teeth or area around the mouth. Certainly we know that in anyone physical stimulation of a local site of pain does relieve discomfort, at least temporarily (see Box 5.1)¹. The similar argument may be made for a tooth eruption and it should not be surprising if children and bang or bump the area around the mouth around this time. Similarly middle ear infection and blocked sinuses or sinus infections can cause pain and discomfort and may lead to banging or rubbing of the area around ears and the upper cheek and bridge of the nose. There is little doubt that children and adults who suffer from reflux as a result of gastro-intestinal problems experienced significant discomfort when reflux occurs. Again the extreme discomfort and burning sensation in the chest and throat may lead to scratching, punching or hitting of these areas and children and adults may push their fingers or hands into the throat in an attempt to relieve the pain and discomfort. Indications that reflux is occurring and painful include these behaviours as well as excessive drinking, food avoidance, approachavoidance behaviours prior to food (repeatedly sitting down to meals but then moving away), arching of the back (see Box 5.2) and various forms of difficult behaviour in the period following meals.

The eye problems that children adults with Cornelia de Lange Syndrome experience may also evoke temporary or longstanding self-injurious behaviour. If the tear-ducts are not functioning correctly, and consequently no tears are being produced, then it is probable that the surface of the eye will become dry and irritated and this may lead to the child or adult rubbing the eye in an attempt to relieve this unpleasant sensation. Additionally, it is also important to be aware that constant rubbing around the eyes may lead to the eyelashes rubbing on the surface of the eye and causing some discomfort. This is particularly important as children and adults with Cornelia de Lange Syndrome and tend to have long and thick eyelashes.

The role of a potential peripheral sensory neuropathy is worth considering in some detail. The sensation of pain is dampened by a peripheral sensory neuropathy2. Additionally, it is possible that peripheral sensory neuropathy gives rise to a tingling or mild burning sensation in the arms, hands and fingers ³. If this is the case then individuals may respond to this sensation by scratching, picking or biting the area in which the tingling is occurring. When this happens in the absence of any pain the behaviour may become more severe than would otherwise be the case. It should be noted that there is only limited evidence to date that a peripheral sensory neuropathy is evident in people with Cornelia de Lange Syndrome ⁴. However, this possibility cannot yet be ruled out.

Sensory reinforcement

There is some evidence that self-injurious behaviour does occur because it leads to a pleasant sensation that a person finds rewarding and consequently they will show the behaviour in the future 5. The clearest example of this is eye pressing and this commonly occurs when there is damage to the eye which causes the rods and cones in the rear of the eye to be unresponsive to light (see Box 5.3). Under these conditions physically pressing the eye will cause the rods and cones to fire and the individual will “see” flashes and patterns of light. It is not surprising therefore that when someone discovers this way of producing a sensation that they will reproduce it over long periods of time, especially when the eye is not producing any other form of stimulation from light.

There are of course a number of other ways in which the sensation that arises from mild forms of self-injurious behaviour might be rewarding. This effect might be enhanced when there is limited pain associated with the behaviour. Mild face slapping can produce a tingling sensation and pressing and banging the ears can result in “pleasant” noises.

It is also useful to think about the relief of pain and discomfort as a sensory reinforcement process. In this case the reward is not the presentation of something positive after the behaviour but the removal of an aversive or unpleasant sensation. The best example of this is scratching an itch. In this example the itch is scratched because the behaviour of scratching is rewarded by the itch subsiding.

The process of sensory reinforcement is shown in Box below

External causes

When we think about the external causes we mean factors that are in the environment that seem to effect the level of self-injury. The most important of these is the effect that the responses of others has on the self-injury and this usually takes two forms: presenting rewarding attention and removing unpleasant demands. We will describe these in turn.

Positive social reinforcement

As was discussed in Chapter 3 there is a good deal of evidence that self-injurious behaviour can be rewarded or reinforced by the presentation of social contact (attention) and it is important to understand how this process occurs ^{6, 7, 8}. The process is shown in Box 5.5 and the numbers in the figure in Box 5.5. refer to the sequence of events that are listed here:

1. The child is on their own and has no stimulation. Initially, the child may show self-injurious behaviour either because it gives rise to pleasant sensory stimulation or because it relieves discomfort (see section 5.3.1) or as the end result of a stereotyped behaviour or it is simply a chance act (an accidental bump of the head).
2. The self-injury occurs and seen by another person (parent or carer).
3. The other person finds the self-injury unpleasant or aversive and consequently acts to stop the self-injury from recurring or tries to find out the reason for the self-injury.
4. The other person engages with the child who has just shown self-injurious behaviour and whilst preventing further instances of selfinjury and trying to find the cause, may comfort, distract or restrain the person or use any combination of these strategies.
5. The child finds this contact with the other person pleasant and rewarding (reinforcing). This makes it more likely that the next time the person is alone and without contact they will self-injure.
6. The child is alone and has no stimulation (and thus motivated to seek contact). Self-injury occurs because in the past it has led to rewarding social contact with another person. (Go to 2 above).

Once this process has occurred an number of times the child will very quickly learn to self-injure because it leads to rewarding attention from another person. This is not to say that the child necessarily intends to injure him or herself or intends to gain the attention of someone else. It is an entirely natural process whereby a self-injurious behaviour is so unpleasant that it evokes an entirely natural reaction from another person and the contact with that person is also naturally rewarding or reinforcing.

Escape from task demands

The idea that self-injurious behaviour can occur because it leads to attention from other people is not a new one and was first put forward in the late 1960s9. It was some time later that it was also suggested that self-injurious behaviour could have a different kind of effect on other people which is that of reducing social contact under certain conditions ¹⁰. The most common condition being the presentation of tasks that the child may find unpleasant and unrewarding and consequently they do not want to do them ¹¹. This process is depicted in Box 5.6. The numbers in the figure refer to the sequence of events that are listed here:

1. The child is being asked to carry out a task which they do not want to do as they find it: difficult, hard work, painful, unrewarding, or any combination of these factors.
2. The self-injurious behaviour occurs. (Initially, the self-injury may occur at this time simply by chance or as part of a “tantrum” in which the child accidentally self-injures).
3. The other person finds the self-injury unpleasant or aversive and as a result of this does something in order to prevent another selfinjurious response or tend to the results of the first response.
4. The other person engages with the child in order to prevent the self-injury. The response that the other person is making at this point may be no different to that described in the attention example given above. The important point here is that whilst engaging with the child the unpleasant task stops, at least temporarily.
5. The child finds this removal of the unpleasant task rewarding. This makes it more likely that the next time the child is presented with an unpleasant task (and they are thus motivated to escape the task) they will self-injure.
6. The child is being asked to carry out a task which they do not want to do as they find difficult, hard work, painful, unrewarding or any combination of these factors. (Go to 2 above).

As part of our research we observed a young man with Cornelia de Lange Syndrome who showed self-injury at his day centre. When tasks were presented during the day or he was required to change activities this often led to a burst of self-injury and then the demand was removed. This is the chain of events that tends to occur when self-injury is rewarded by escape from demands (see Box 5.7).

In both these processes learning is taking place on the part of the child or adult. Each time the child is in this situation and shows the behaviour and is rewarded, this strengthens the association between the situation, the behaviour and the reward and makes it much more likely that this will occur in the future (see Box 5.8).

It should be noted that in both of these examples only one type of reward is being considered. In the positive reinforcement example, attention appears as the reward. However, it is entirely possible that along with the attention any number of other rewards are also present. This may include food, drinks and activities in order to try and distract the child from the self-injurious behaviour. When this happens the association between behaviour and reward is strengthened further as the child learns that self-injury leads both to attention and the presentation of these other items. Similarly, it may be the case that it is not necessarily just unpleasant task demands that are removed after self-injurious behaviour. It is possible that for children who do not like social contact that self-injury can be reinforced simply by the removal of social contact that does not have any demands associated with it ¹².

These descriptions of the process of rewarding self-injurious behaviour have only focussed on the way in which the child is rewarded for showing self-injurious behaviour. It is important to also think about the other person in this interaction and how their behaviour is also rewarded8. If we consider this process within the positive reinforcement example that we have looked at above, then we can see that not only is the other person rewarding the child but the child is also rewarding the other person. This process is shown in Box 5.9. The numbers in the figure in Box 5.9 refer to the sequence of events described here:

1. The child is on their own and has no stimulation. 
2. Initially, the child may show self-injurious behaviour either because it gives rise to pleasant sensory stimulation or because it relieves discomfort or as the end result of a stereotyped behaviour or it is simply a chance act.
3. The self-injury occurs and seen by another person (parent or carer).
4. The other person finds the self-injury unpleasant or aversive and consequently acts to stop the self-injury from recurring or tries to find out the reason for the self-injury.
5. The other person engages with the child who has just shown self-injurious behaviour and whilst preventing further instances of selfinjury and trying to find the cause may comfort, distract or restrain the person or use any combination of these strategies.
6. As the child has now received a reward there is no longer any motivation for the self-injury to continue and the self-injurious behaviour stops.
7. As the self-injurious behaviour has now stopped the other person has been rewarded by the removal of the unpleasant event (the self-injurious behaviour). This reward is the feeling of relief that happens when a child stops selfinjuring, even for a short period of time.
8. As the response by the other person to the self-injury is rewarded it makes it more likely that the person will make the same response to the self-injurious behaviour in the future and so reward the person again.

It is worth thinking about some other things that are always occurring in this process. One is what happens if the other person does not make a rewarding response to the self-injury. Under these circumstances the child will still have a need for the reward (i.e. is motivated see step 1 in Box 5.9) and so the self-injury will continue. As the self-injury continues so the other person will present more things until they eventually hit on the right thing and then the child will stop the self-injury. In this way the person is inadvertently taught by the child precisely how to reward the self-injury.
This sequence of events shows that just as the other person is inadvertently rewarding the child for showing self-injury, so the child is inadvertently rewarding the other person for rewarding the self-injury. This does not mean that the child intends to control the behaviour of the other person, it is simply the consequence of the natural sequence of events that occurs around any bout of socially reinforced self-injurious behaviour.

Self-injury as communication

When the social reinforcement process is described in this way it has led some people to describe self-injurious behaviour as being very similar to communication ^{13, 14}. That is the selfinjury is able to affect the behaviour of other people in the same way that communication can. With self-injurious behaviour that is socially reinforced the child effectively has the capacity to ask for things and refuse things. This is a useful analogy as it allows us to understand that selfinjurious behaviour can in fact be a very adaptive behaviour in some respects. This is particularly the case when people have poor expressive communication and a limited repertoire of behaviours that they may call upon in order to affect the behaviour of others. It was noted in a Chapter 3 that poor expressive communication and a greater degree of intellectual disability are risk factors for development of self-injurious behaviour. When the mutual social reinforcement process is operative, self-injurious behaviour can come to substitute for a limited expressive communicative ability.

There are two points which should be made with regard to the similarities between self-injurious behaviour and communication. The first is that the analogy only stretches as far as the pragmatics of communication i.e. the capacity for behaviour to influence the behaviour of others. Unlike language there are few rules and as a communicative act the behaviour is extremely crude. Second, when the analogy is applied to the process that is described in Box 5.8 it is clear that self-injurious behaviour is not necessarily due to a frustration with communication. Rather, it is a communicative act in itself.

It is worth thinking about the communicative analogy with regard to some specific features of Cornelia de Lange Syndrome. First, in Chapter 2 we showed that children and adults who have Cornelia de Lange Syndrome have very poor expressive communication and we had previously identified poor expressive communication as a risk factor for self-injurious behaviour. Thus, this risk marker can interact with the reinforcement process to cultivate self-injurious behaviour. Second, as we described in Chapter 2, children and adults with Cornelia de Lange Syndrome tend to have a severe or profound degree of disability. By definition this means that they have a limited repertoire of behaviours with which to influence others. Under these two circumstances self-injurious behaviour that is socially reinforced in a way that makes it communicative can emerge and easily become established in an individual’s repertoire.

The effect of “setting events” on self-injury

Within the last ten years more attention has been paid to the fact that even when self-injurious behaviour is socially reinforced it tends to vary in frequency across days and can also vary within a day. If the social reinforcement theory was a sufficient explanation then this should not necessarily be the case. In order to account for this variability researchers have looked at what are called “setting events” to try and understand why selfinjurious behaviour should be occurring frequently at some times and not at others. The term “setting event” refers to something that influences the relationship between a situation and the likelihood that a behaviour will be shown.

One type of setting event that is relevant to understanding self-injurious behaviour in children and adults with Cornelia de Lange Syndrome is pain and discomfort. As we have discussed there have been a number of demonstrations that, for example, self-injurious behaviour can be worse when demands are made on individuals and in the past the self-injury has been reinforced by the removal of demands (see Box 5.6) ¹⁵. It has also been shown that this relationship may be even stronger when particular setting events such as low mood, fatigue or illness are present ^{16, 17, 18}. In other words demands may be made at times when people are not experiencing low mood, fatigue or discomfort and this will not lead to self-injurious behaviour.

However, on other occasions if an individual is experiencing low mood, is tired or is experiencing discomfort and then a task demand may trigger the self-injurious behaviour. The reason for this is that the motivation for escaping a task is usually higher when anyone is tired or in discomfort (do you want to clean the house when ill or tired?) This shows how some biological factors might interact with psychological factors to raise the probability that a behaviour will occur.

Changes in the severity of self-injury over time

Whilst the social reinforcement theory can account for why self-injurious behaviour may be maintained or may continue, it cannot necessarily explain why the self-injurious behaviour occurred in the first place. For the social reinforcement theory to be right the behaviour has to occur before it can become reinforced. To explain this problem it has been suggested that self-injurious behaviour that is socially reinforced first started for another reason before becoming rewarded either by social contact or the removal of demands. The idea is that the behaviour may occur because it is reinforced by the sensory stimulation (see Section 5.3.1) or in response to a minor illness or discomfort or as a chance act, for example during a tantrum. Once the behaviour has occurred under these circumstances it may then become reinforced in the way that is described in Sections 5.3.2 and 5.3.3.

Once self-injurious behaviour becomes socially reinforced and occurs regularly there are some reasons why it may gradually become severe over time. In order to understand this increasing severity over time it is important to remember the reason that people reward (reinforce) self-injurious behaviour. Self-injurious behaviour is reinforced by other people because they experience it as unpleasant or aversive and want to stop it. It then follows from this that when a behaviour is more severe or potentially injurious then people are more highly motivated to stop the behaviour and thus and more likely to respond and reinforce the behaviour. (see Box 5.10). When we consider the development of self-injurious behaviour over time it becomes easy to see why self-injury might increase in severity. It is highly likely that it is the more injurious or damaging responses that lead to a much quicker rewarding response by others. Consequently the child learns to show a more damaging response as opposed to a less damaging one. Gradually over time this ratcheting up of severity will lead to more damaging behaviour.

There is another way in which self-injurious behaviour might increase in severity when it is socially reinforced. When any behaviour is reinforced or rewarded it is possible to decrease the behaviour by simply withholding the reward or reinforcement. This is called extinction. However, the behaviour does not necessarily decrease immediately. In fact it shows a characteristic pattern which is called an extinction burst ¹⁹. This means that the behaviour increases in frequency and intensity before finally decreasing. If when a behaviour such as self-injury is being socially reinforced an attempt is made to withhold the rewards, this is usually done by ignoring the behaviour. When this happens the behaviour may increase to such an intensity that it is impossible not to respond and consequently reinforce the behaviour. When this happens the person has then learned not to show the behaviour at a low frequency and low intensity but to show a much higher intensity and frequency of the behaviour. In the future the behaviour will then occur at this high rate and intensity.

The reinforcement or greater reward for more severe self-injurious behaviour is best understood by thinking about what is called the response efficiency of the behaviour ²⁰. When a behaviour is socially reinforced the severity of the behaviour is to some extent determined by its efficiency. A behaviour that is very efficient will have very little cost to the individual, will take little effort to carry out and will result in no pain or discomfort but will have a very high return. That is, it will commonly be reinforced on every occasion, with a great deal of reward and this will occur very quickly. Under these circumstances we would say that a behaviour has high response efficiency. For self-injurious behaviour, one of the balances to the reinforcement that occurs is the potential pain or discomfort that accompanies each and every act of self-injurious behaviour. In other words, if the reward for showing self-injury was very small but the pain was very high then the behaviour would tend to occur very infrequently or not at all because the cost of the behaviour of outweighs the return. However, it is important to remember that pain, particularly pain in the peripheral nervous system, maybe dampened in individuals with Cornelia de Lange Syndrome (see Chapter 2) and this may mean that there is a lower cost to the behaviour than would otherwise be the case.

Loss of control

In Chapter 3 it was noted that some people who shows self-injurious behaviour also show behaviours that seem to indicate that they are unable to control their own self-injury. These behaviours were referred to as self-restraint and a preference for imposed restraint. It is difficult to understand why behaviours such as self-restraint should occur and why people should want to be restrained if the self-injurious behaviour is acting as a form of communication. The social reinforcement theory suggests that the behaviour is under the control of the individual and the behaviour is shown when particular motivational conditions arise. If this is the case then it is difficult to see why someone should try to actively restrict their behaviour by seeking restraint when they could just simply not show the behaviour. The argument that is often put forward in response to this is that the self-injurious behaviour is painful and consequently the person does not want to experience the pain ²¹. However, if this is the case then it is not clear why the person does not simply stop showing the behaviour because the response efficiency is now imbalanced and there is now a comparatively poor return for the behaviour. Consequently, when self-restraint is occurring it seems likely that the social reinforcement theory might be less applicable.

Under these circumstances it has been suggested that the self-injurious behaviour has taken on a “compulsive” quality and consequently the individual will feel driven to show the self-injurious behaviour or may not be able to inhibit the behaviour ²². The self-restraint than arises as a method of self control of a behaviour that the individual experiences as painful but is unable to inhibit. In Chapter 4 we described a study in which we had found that for those individuals with Cornelia de Lange Syndrome who showed self-injurious behaviour and other compulsive behaviours they were more likely to show selfrestraint and appeared to be trying to exert control over their own self-injurious behaviour. Clinically, we have often observed self-restraint in people with Cornelia de Lange Syndrome who show self-injurious behaviour and it is a real possibility that for these individuals the behaviour is not completely under their control and they are trying to seek some external help in managing the behaviour. Their solution to this problem is self-restraint.

It is interesting to speculate why this problem might arise more in Cornelia de Lange Syndrome than we might expect. The answer might lie in disturbance of the serotonergic system. In Chapter 2 we noted that compulsive behaviours are much more common in individuals with Cornelia de Lange Syndrome than a comparable group of individuals with the same degree of intellectual disability. Additionally, a study in the 1970s showed that serotonin levels in Cornelia the Lange Syndrome were lower than normal ²³. We have previously noted that one potential cause of compulsive behaviours is serotonergic disturbance. Although speculative at this stage it is entirely possible that a fundamental disturbance of serotonin exists in children and adults with Cornelia de Lange Syndrome and that when self-injurious behaviour occurs it becomes compulsive and consequently the individuals are unable to control their behaviour.

Summary

It is likely that the causes of self-injurious behaviour in children and adults with Cornelia de Lange Syndrome are not very different from other people who have an intellectual disability. Medical conditions associated with pain and discomfort, self-injury rewarded by sensory stimulation and the presentation or removal of social contact are all reported as important causes in all people who have intellectual disability. The difference for people with Cornelia de Lange Syndrome may well be that:

• they experience more medical conditions that can give rise to self-injury,
• they have poorer expressive communication,
• consequently self-injury may be more likely to come to serve a communicative purpose,
• and that they may be more likely to experience difficulties in inhibiting a self-injurious response than other people.

References

Chris Oliver

by Chris Oliver, Jo Moss, Jane Petty, Kate Arron, Jenny Sloneem, Scott Hall

Source:

CdLS Outreach United Kingdom and Ireland; Self-injurious behaviour in Cornelia de Lange Syndrome A Guide for Parents and Carers, published on 20 juin 2003

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