AUTISM : CURRENT CONTENTS 24
This summary of selected recently published material begins with a discussion whether motor impairment may be viewed as a diagnostic feature of Asperger Syndrome or, more likely, as a commonly comorbid feature (with an additional conclusion that autism may be a condition with no symptom coherence or clear boundaries).
There follows a description of attempts to specify the nature of language impairments that do exist in Asperger Syndrome, with reference to no primary disability but to common weaknesses in the use of pragmatic language especially when there is some emotional colouring to the conversational content.
The final two sections explore the issue of social processing and the understanding of mental states in other people, with the suggestion that a significant problem may arise in respect of a desire or motive to share affect or interaction rather than some specific weakness in understanding intentions; and reference is made to the outcomes of a study exploring patterns of CNS (dys)functioning as a basis for observed limitations in joint attention among children with autism.
Motor Impairment in Asperger Syndrome
Asperger Syndrome has now been recognised for more than 10 years as a separate clinical entity in both the ICD and the DSM classifications. Diagnostic features include repetitive and idiosyncratic interests, pursued to an obsessive extent alongside impaired social interaction, but with apparently or superficially normal cognitive and language development. However, the precise status of motor impairment is not clear. Both diagnostic manuals refer to clumsiness of movement, but motor disability or disadvantage is not set down as an essential or defining feature of Asperger Syndrome.
In the original paper by Asperger (1944) some weight is given to motor clumsiness in his description of the syndrome ; and the four case studies given as illustrations each contain references to poor co-ordination or a lack of fluency in movement.
In her presentation concerned with Asperger Syndrome, Wing (1981) highlighted the significance of motor problems ; and, having earlier noted that a significant percentage of children with autism also showed clumsiness, held that ill-coordinated movements and odd posture were major features of Asperger Syndrome.
The review of Green et al (2002) reports only a small number of studies which provide sufficient information by which to begin estimating the likely prevalence of motor impairment, but there is still some inconsistency.
For example, Gillberg (1989) described how more than 80% of his Asperger sample produced scores on the motor component of the Griffiths Test which fell significantly below (more than 15 points) the overall quotient. It is further noted that this study omitted data from the hand-eye co-ordination section of the test but, given converging evidence for difficulties with fine as well as gross motor skills among Asperger children, one would conclude that Gillberg's already high prevalence figure for motor difficulty might still underestimate the real incidence.
Similar findings were obtained by Ghaziuddin et al (1994) who tested children and young people with Asperger Syndrome and high functioning autism on a test of motor functions (gross, fine, and upper limb co-ordination). They found that 8 of the 11 members of the Asperger sample showed unusually poor performance on all three sections of the test, and the remaining 3 children showed similarly poor performance on at least one section.
This finding was supported by the work of Klin et al (1995) who found fine motor deficits in 90% of their Asperger sample but only 32% of their sample of children with high functioning autism. Prevalence of gross impairments was 100% and 63% respectively.
On the other hand, consistent and significant weaknesses were not observed by Manjiviona and Prior (1995) in their assessment of Asperger children on a test of motor impairment, although it is possible that results may have been skewed by the higher scores of some members of the sample whose ages were outside the norms for the test.
The current authors (Green et al : opp.cit) set out further to investigate the extent and severity of motor impairment in Asperger Syndrome, and to compare a sample of children so-diagnosed with a sample of children with a primary diagnosis of motor difficulty but matched for cognitive abilities. This was not only to gain an indication of the prevalence of motor difficulty in the Asperger children but also to determine whether actual deficits can be differentiated from those observed in children with alternative developmental disorders.
The tests used were the Movement Assessment Battery for Children (Henderson and Sugden 1992) which gives measures of manual dexterity, ball skills, and balance ; and a test of gesture (or, at least, the ability to mime the use of objects from memory and to imitate movements) produced by Cermak et al (1980).
The participants included a group of 11 children with Asperger Syndrome and 9 with specific developmental disorder of motor function (i.e. impairment in motor co-ordination that is not a result of overall intellectual retardation or of some congenital or neurological condition). The ages ranged from 6+ to 10+, and the children attended mainstream schools.
The findings indicated that in the (small) sample of children with Asperger Syndrome, motor impairment was observed throughout with the scores of all 11 children falling below the 15th. percentile point, an 9 scores below the 5th..
On the Movement ABC, the tasks involving aiming and catching a ball best distinguished the Asperger group from the specific developmental disorder (SDD) group.
A specific search through previous studies confirmed that ball skills are particularly affected among Asperger samples ; and it was recognised that, of the various skills assessed, ball skills are likely to be most influenced by social pressures.
In other words, the deficit observed may not be just a matter of some specific coordinatory weakness but a reflection of a lack of participation in group games and of minimal practice of ball skills which may feature significantly in those group games. In addition, the authors comment that ball skills might gain a particular emphasis since, in everyday school and playground circumstances, a failure to aim or catch a ball will stand out more obviously than a failure to cope with a pegboard or to copy written material accurately.
Alternatively, Tantam (1991) proposes that children with difficulties of an autistic type have particular problems in copying movements that someone else is making and are unable readily to take advantage of demonstrations, but children with Asperger Syndrome as opposed to children with "classical" but high functioning autism do at least attempt to interact with others so that their observable behaviour contains more examples of poor motor performance including weaknesses in ball games.
In respect of the use of gesture, there is a general acceptance that this forms an important part of social interaction and is likely to have been learned, at least partially, via imitation. In the present test involving miming the use of objects and of copying sequences of movements, the Asperger group did less well than the SDD group in both areas (although both groups performed more poorly than normally developing controls).
The authors speculate that the weakness with regard to mime or imitation may be linked to a general communication difficulty. Alternatively (or in addition) it may reflect some deficit in motor planning.
Rogers et al (1996) began with a hypothesis that motor-imitation might be a core deficit in autism resulting in rather than resulting from other deficits in social cognition, but modified their view to argue that the underlying deficit is a matter of (limited) executive functioning.
In other words, problems with imitation reflect an inability to form a plan of the required sequence of movements and to hold it in working memory.
Green et al hold that their current findings offer more support for this executive functioning hypothesis than for an alternative hypothesis which would explain the imitation weakness in terms of some underlying symbolic or representational deficit.
Returning to the present study, it was noted that 3 of the Asperger group had originally been referred for assessment of suspected motor difficulties and it was not until the families had been interviewed and a fuller awareness of the children's characteristics established that it became clear that the children met criteria for diagnosis with Asperger Syndrome.
The authors comment that this adds weight to the view that co-occurrence of impairments within developmental disorders is so common as to be the rule rather than the exception, but note that there remains pressure to produce coherent (and unitary ?) descriptions of the various developmental impairments.
They recognise that clumsiness is a relatively common accompaniment to many disorders with many children initially referred for some other problem found to have concomitant difficulties with tasks involving motor control. It is suggested, therefore, that the prevalence of such comorbidities may mean that the attempt to categorise children within one specific and discrete diagnostic box is inappropriate.
They go on to conclude that autism is not simply characterised by symptoms which are elusive and open to subjective interpretation, but that autism may be a condition which has no clear boundaries. Thus, instead of looking for symptom coherence, one may need to look for particular patterns of comorbidity reflecting shared vulnerability of various faculties to negative genetic or environmental impacts at particular sensitive periods of development.
Conversational Style of Children with Asperger Syndrome
In the introduction to their study of the kinds of difficulty observed in the use of (pragmatic) language by children with Asperger Syndrome, Adams et al (2002) describe how research over the last decade or so may have been organised according to differing definitions of the syndrome but there has been a common focus on problems with social communication, idiosyncratic interests, and interaction. It has not generally been the case that significant language delays or disabilities have been included in the descriptions of Asperger Syndrome.
However, many children and young people who meet the accepted criteria for Asperger Syndrome do demonstrate subtle delays or deviations in their language development in the early years and maintain long term idiosyncrasies in pragmatic language and communication despite satisfactory grammatical speech.
For example, Gillchrist et al (2001) showed that children with Asperger Syndrome were comparable to children with high functioning autism in respect of early abnormalities of language such as verbal rituals, stereotypical utterances, and inappropriate questioning. However, they were less prone to other deviations, such as echolalia or pronoun confusion ; while more prone to later weaknesses with reciprocal conversation and pragmatics.
There is an increasingly common view that the superficial verbal fluency and apparent conceptual understanding in the individual with Asperger Syndrome may often mask a lack of actual understanding so that pragmatic conversation is inhibited and social communication may remain at a rudimentary level.
Further, while grammatical accuracy and vocabulary knowledge may be entirely adequate in children with Asperger Syndrome, there is evidence (e.g. Ghaziuddin and Gerstein 1996) that pedantic speech - which refers to a style of speaking where there is far more information offered than the topic or the purpose of the conversation require - could be the means of differentiating children with Asperger Syndrome from children with high functioning autism.
This characteristic difficulty persists despite the observation that comprehension of language is a relative strength among children with Asperger Syndrome, with the implication that its source lies elsewhere ... i.e. in a difficulty with implementing the (social) rules of language.
It is also noted (see, for example, Bishop 1989) that a high proportion of children with semantic-pragmatic language disorder experience reciprocal social impairments which may overlap with Asperger Syndrome.
So, while Asperger Syndrome is defined as a condition in which there is no clinically significant delay in the use or reception of language, it remains the case that such individuals do show problems in language use and communication ; but the precise nature of these difficulties has not been examined.
The purpose of the study by Adams et al (opp.cit) was to apply techniques of discourse analysis to the language style of children with Asperger Syndrome compared to a group of children with conduct disorder. Compared to the conduct disordered controls, do the Asperger children show more pragmatic weaknesses ? Do they seek to dominate conversations ? Are there differential effects of the topic of the conversation upon the conversational style ?
19 boys were included within each group, aged between 11 and 19 years, all with a non-verbal IQ of at least 70. All participants were put through a structured interview, along with the Test for the Reception of Grammar and the British Picture Vocabulary Test.
In addition, conversational skills were assessed by means of the Autism Diagnostic Observational Schedule which provides standard contexts to assess communication and social interaction.
In particular, two types of conversation were recorded for analysis .... one in which the participant is asked to describe two or three emotions and the context where they might be evoked, followed by a discussion about friendships and relationships ; and the other where the participant reports relatively "neutrally" on some non-routine event such as a trip out or something which happened at school.
The analysis examined the content of the utterances in terms of particular functions, such as
" an initiation " which seeks information. There may also be neutral parts which serve simply to maintain the interaction (e.g. Question : How long have you been working at this ? Answer : About 6 months [ Neutral Part : But I wouldn't say I was much good at it ]). Communicative acts may include requests for acknowledgement ..... e.g. " I like football "
" Do you ? " ; requests for clarification ; and statements.
The analysis also explored the extent to which one partner dominates the conversation by, for example, repeatedly seeking information ; or is assertive in trying to initiate conversation ; or is responsive in replying to questions or requests for information.
"Meshing" refers to the extent of fit between the first part, such as a question, and the response.
The main finding of the study was that the group with Asperger Syndrome showed significantly more pragmatically problematic responses than the control group.
While the two groups showed largely similar rates of responsiveness, the analysis of the quality of responses showed that the Asperger individuals showed less appropriate responses and an inferior rate of meshing.
The finding of considerable pragmatic problems in the target group was thought unlikely to be due to problems of comprehending the questions since there was no difference between the groups on measures of verbal comprehension.
This conclusion was supported by the further observation of differences in frequency between the two groups of pragmatic problems between the two conversational conditions. The Asperger group were significantly more likely to show impairments in the emotional conversation than in the neutral one ; the control group showed no such difference.
The authors held, accordingly, that it is not a question of the Asperger individuals having pragmatic problems across the board ; rather, pragmatic problems are influenced by context and problems are particularly likely when the conversation has some emotional content. There is no primary language impairment in Asperger Syndrome, but a problem with understanding emotional concepts.
Meanwhile the Asperger group was found generally to be more talkative than the control group, showing more initiations, but with no real evidence for their seeking to dominate conversations or for any greater verbosity on their part. However, a small number of individuals within the Asperger group showed a tendency to be markedly talkative ; but even these individuals did not respond in this way when it came to the "emotional" conversation.
In other words, interaction between individuals and contexts makes for difficulty in pinpointing conversational strategies and styles among Asperger individuals. Some individuals will be assertively talkative, others rarely initiate conversation (although the relatively more common "pedantic" manner within an Asperger sample would stand out in a social conversation and would be remembered).
The authors acknowledge the difficulty in identifying an ideal control group, noting the problems in gaining a flowing conversation with most adolescents diagnosed with a conduct disorder.
They also recognise the small size of the samples but the relatively wide variability of conversational behaviours.
Therefore, interpretation of findings need to be a little cautious ; but they conclude that there is evidence to support the view of pragmatic weaknesses as a characteristic of Asperger language style with implications for social interaction.
Understanding of the Mental States of Other People
There is now a general acceptance that children with autism have a characteristic weakness in recognising or appreciating the thoughts, beliefs, and points of view of others, but Carpenter et al (2001) address the question of the extent to which children with autism understand other mental states which normally-developing children are able to understand at an earlier stage. Meanwhile, it is noted that autism can usually be diagnosed with reliability at an age younger than that at which traditional theory of mind tests can be applied, begging the question how far back go the deficits in theory of mind among children with autism.
One of the earliest mental states that can be recognised and understood is intention ; and evidence suggests (e.g. Tomasello et al 1993) that children still a little short of their first birthday can appreciate that other people do have intentions and that this understanding is a precursor of much of the social-cognitive skill which begins to emerge at this time.
This is significant for the study of the nature of autism because many of the consistent differences between children with autism and either children with other forms of developmental delay or children showing no developmental anomalies are concerned with social-cognitive skills like joint attention, communication, and imitation.
Two recent studies into the understanding of intentions on the part of children with autism have produced differing results. On the one hand, Phillips et al (1998) assessed children engaged on a target shooting game and found that those with autism were less able than controls to identify which target they had intended to hit ; but this finding was not replicated by Russell and Hill (2001) who asked children with autism and normally-developing children, matched for mental age, to report on their own and others' intended targets.
The current authors, Carpenter et al (opp.cit), used a different non-verbal procedure to investigate understanding of intentions.
Young children with autism (actual age range 40-57 months) and a control group with developmental delay (actual age range 31-60 months), matched for chronological and mental ages, watched while an experimenter tried to pull apart two halves of a shape. In one "target" condition, the task was successfully demonstrated ; but in the "intention" condition, the task was attempted but not completed (hands pulling on the two ends, but slipping off). There were two further conditions. Firstly, the shape was presented having already been pulled apart, but with no demonstration of how this was done ; and secondly, the experimenter completed slightly different actions from the target condition albeit in the same general position and manner.
The findings were that children in both groups performed similarly in their attempts to replicate the task with success most often associated with the target and intention conditions. There appeared no significant differences between children with autism and children with developmental delays on any indicator of intentional understanding.
Thus, even in the condition where they were shown only unsuccessful attempts to demonstrate the task, the children with autism were as likely as the control children to perform the target task ; and they carried out the actions just as quickly.
The authors highlighted the significance of this finding in that the children with autism resembled the children with other developmental delays despite the converging evidence that autism is linked with a consistent weakness with imitation.
However, they acknowledge some limitations with this present study, notably the absence of data on how older and normally-developing children would perform on this task. There is, in other words, the possibility that the lack of autism-specific deficits is a matter of relatively poor performance on the part of the developmentally-delayed control group.
On the other hand, if one can be reasonably confident that these procedures do provide a measure of children's understanding of others' intentions, then the current study adds support to the existing view (as set out by Russell and Hill - opp.cit) that young children with autism, even those with lower mental ages than quoted in previous research, do not show specific deficits in understanding the intentions of other people.
The logic is for assessing even younger children given the possibility that there may be autism-specific weaknesses in this area but that the children in the present sample had already out-grown them. In support of this view, the authors noted that there was a positive correlation between chronological age and a measure of intentional understanding.
In any event, the authors still argue that these results have important implications for an understanding of social-cognitive development in children with autism.
Deficits in joint attention or attention-following appear well before theory of mind deficits can be demonstrated, and one school of thought attributes such weaknesses to a failure to understand others' intentions ; but the present evidence suggests that this explanation is not adequate.
A further study (Carpenter et al - in press) goes on to demonstrate that these same children, shown to have no major deficits in understanding intentions, do show significant deficits in joint attention skills. This begs the question of what, if not a deficit in understanding intention, underlies the joint-attention weaknesses.
As one hypothesis to answer this question the authors offer support to findings elsewhere
(such as Hobson 1993) that the significant problems concern the ability or motivation to share affect, interest, and attention with other people.
Understanding of others' intentions may be one component of joint attention skill, but is not sufficient in itself to explain this latter "robust" deficit.
The authors summarise and conclude that the development of understanding of others' intentions appears largely intact in young children with autism who, nevertheless, show characteristic and marked deficits in joint attention.
If this finding is replicated in further studies, especially involving younger participants, there will be a problem for theories concerning theory of mind or executive functioning which depend to a significant extent upon the failure among children with autism to understand intentionality. Some further hypothesis will be required to explain the early and consistent weaknesses in joint attention in autism.
Neurocognitive Function and Joint Attention Ability
Neatly following from the above discussion about the underlying basis of joint attention deficits in autism is the work of Dawson et al (2002) who introduce their study with an acknowledgement that, despite the many years since autism was recognised as a clinical syndrome, the precise nature of brain dysfunction remains unclear.
Autism is characterised by consistent and severe impairments in the processing of social and emotional information, such as theory of mind, interpretation of gesture, etc., and this pattern suggests that autism is linked to dysfunction of that part of the CNS involved in social cognition, namely the amygdala, hippocampus, and entorhinal cortex (medial temporal lobe areas) plus parts of the ventromedial prefrontal cortex.
Evidence to this effect emerges from neuropsychological assessment, neuro-imagery, and autopsy studies.
Earlier studies completed by Dawson and her colleagues have tested the hypothesis linking autism with medial and ventromedial areas by means of delayed non-matching to sample tasks, and they demonstrated that the performance of children with autism was impaired relative to what was observed among children in a control group with developmental delay and a normally-developing group.
The current study set out to extend the research into the relationship between patterns of neuropsychological functioning and the severity of autistic symptoms firstly by using younger children as participants (3 to 4 years rather than 5+), secondly by increasing the range of tasks to be attempted, and thirdly by using multiple measures of core constructs (notably joint attention) to allow for greater sensitivity in testing the significance of the relationship.
Two reasons were given for using tasks which focus upon joint attention and its relationship to neurocognitive functioning.
Impairments in this area have been well replicated in research into autism and they seem to be both specific and universal among children with autism. In fact, weaknesses in joint attention, which is normally present in children at around 1 year, have become part of the criteria by which initially to identify autism.
Further, the role of executive function has been investigated with regard to its role in the development of joint attention and theory of mind. Given a hypothesis (Rochat 1999) that joint attention is a precursor of theory of mind skills (which have been shown to correlate positively with executive function ability), it was planned to use this present study to seek clues concerning the role of executive function to the early development of theory of mind.
In this present study, three groups of children matched for mental age were assessed ; 72 children with autistic spectrum disorder (49 children with autism and 23 with pervasive developmental disorder), 34 children with developmental delay but not autistic, and 39 children developing normally.
The tasks included the following :
Ventromedial Prefrontal Tasks.
A delayed non-matching to sample task where the child is shown some object which covers a wooden bowl. If the object is moved, the child can retrieve a small reward from the bowl. After a delay, the procedure is repeated but with the original object and a new object, and the child can only obtain the reward by moving the new object.
An object discrimination reversal task where the child has to learn which of two repeatedly presented objects is associated with a reward. After the child has demonstrated awareness of the connection by reaching for the correct object 5 times in succession, the situation is reversed and the child has to learn that the reward is now under the other object. The results are scored in terms of number of errors to criterion, number of perseveration errors, etc..
Dorsolateral Prefrontal Tasks
An " A not B " task where the child is shown two cups, one to his right and the other to his left. The child watches while a reward is placed under one cup, then a screen is placed in front of both cups for 5 seconds, and the child is asked to locate the reward when the screen is removed. If the child chooses correctly, he keeps the reward ; if not, he is shown where the reward is, but not allowed to have it. The procedure is repeated after 5 seconds, but when the child has chosen correctly on two successive occasions, the position of the reward is switched to the other cup. After two switches but two correct successive choices, the delay is increased to 12 seconds. The focus is upon the percentage of occasions where the child makes the right choice.
An " A not B " task with invisible displacement which is a more difficult version of the above. The child sees a reward placed inside a box whose open side is then covered with a cloth and is placed to the right or left of the child. A screen is placed between child and box for 5 seconds during which time an identical box is placed on the other side of the child. The child's task is to locate the reward which is shifted from one side to the other after two successful trials.
Spatial Reversal Task
This task is similar to the above in assessing spatial memory for a hidden object except that the child does not see the object being hidden. Two identical cups are placed to the right and left of the child which are then concealed by a screen while a reward was inserted in both. Whichever side is selected by the child on the first trial is deemed the preferred side, and in subsequent trials the (one) reward is placed in the cup on that side. The side is switched after 4 correct trials.
Joint Attention Tasks
The kind of task here is illustrated by a situation in which the child is allowed to play with a toy. There are 4 coloured cardboard crosses mounted on the wall at the child's eye level, and in various positions .... to the right or left, in front, or behind the child. The examiner seeks to attract the child's attention and eye contact, and then to establish joint attention on one of the crosses either by gazing at it or pointing at it. A positive trial is scored when the child turns towards the cross within 15 seconds of the stimulus.
The findings demonstrated that the young children with ASD performed similarly to the mental age matched children with developmental delay or normal development on the range of tasks which assessed executive functions.
This suggested that, while both samples of children with disabilities had some impairments of executive function, there is no reason to link autism with a unique pattern of executive weaknesses at this age.
An executive function impairment appears, therefore, not to be a good early diagnostic pointer towards autism because performance on relevant tasks among children with autism of this age (3 to 4 years) is much the same as that observed among non-autistic children of comparable mental age.
The authors quote the suggestion of Griffiths et al (1999) that the executive function impairments that have been associated with autism do not become evident until a later age. This is plausible given that executive function skills only begin to emerge during the pre-school period so that a failure to identify some consistent set of deficits in this respect would be predictable.
Autism specific prefrontal impairments may not be observable until the frontal lobe has developed to a greater level of maturity and when, in the absence of some neurological dysfunction, social processing is becoming established. There is a possible implication of some specific medial temporal lobe dysfunction disrupting these emerging social-processing skills, and having a negative impact upon prefrontal skills of a kind frequently linked with autism.
Support for this kind of view is found in the growing evidence (e.g. Baron-Cohen et al 2000) for amygdala dysfunction among children with autism which may interfere with the subsequent development of some of the prefrontal functions which emerge in the preschool period and which are facilitated by social interactions.
The findings of this current study also support the hypothesis that performance on tasks linked to the medial temporal lobe - ventromedial prefrontal circuit would be particularly well correlated with joint attention ability. Children with ASD performed worse on the joint attention tasks than did children in either of the control groups.
The authors then go on to speculate about the significance of these findings, and restate their view that rule learning regarding the relationship between stimulus and reward is critical for various aspects of social functioning, including the development of joint attention and theory of mind. The expected reward value of some stimulus begins to motivate attention by the time a child is 1 year old, but it may be very difficult for the child with autism to learn how to make these expectations because social feedback (such as a smile in response to some action) is less predictable and more variable than some non-social or tangible reward.
In this context, it is significant to note the findings of Gergely and Watson (1999) that, compared to normally developing infants, children with autism show a strong preference for highly contingent and non-variable feedback ....i.e.. non-social and tangible rewards.
The authors acknowledge some limitations of this current study, such as the low variability within the sample of normally developing children in respect of joint attention ability, or the desirability of gaining normative data about the association between performance on these neuropsychological tasks and joint attention. Nevertheless, they conclude that their results provide initial evidence concerning what may underlie a limitation in joint attention which is widely regarded as one of the core impairments in autism.
M.J.Connor August 2002
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© Mike Connor 2002.
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