Three Diagnostic Approaches to Asperger Syndrome: Implications for Research

Objective: To examine the implications for research of the use of three alternative definitions for Asperger syndrome (AS). Differences across the three nosologic systems were examined in terms of diagnostic assignment, IQ profiles, comorbid symptoms, and familial aggregation of social and other psychiatric symptoms. Method: Standard data on diagnosis, intellectual functioning, comorbidity patterns, and family history were obtained on 65 individuals screened for a very high probability of having autism without mental retardation (or higher functioning autism, HFA) or AS. Diagnoses of AS were established based on three different approaches: DSM-IV, presence/absence of communicative phrase speech by 3 years, and a system designed to highlight prototypical features of AS. Results: Agreement between the three diagnostic systems was poor. AS could be differentiated from HFA (but not from PDD-NOS) on the basis of IQ profiles in two of the three systems. Differences in patterns of comorbid symptomatology were obtained in two of the three systems, although differences were primarily driven by the PDD-NOS category. Only one of the approaches yielded differences relative to aggregation of the broader phenotype in family members. Conclusions: Diagnostic assignments of AS based on three commonly used approaches have low agreement and lead to different results in comparisons of IQ profiles, patterns of comorbidity, and familial aggregation of psychiatric symptoms across the approach-specific resultant groups of HFA, AS, and PDD-NOS.     

Review of the Asperger Syndrome Diagnostic Scale

The Asperger's Syndrome Diagnostic Scale (2001) was reviewed to determine it's reliability, validity, and clinical utility in the diagnostic process for pervasive developmental disorder, specifically Asperger's syndrome. Concerns were raised about validity of the instrument, population upon which the instrument was normed, capability of the instrument to provide accurate differential diagnoses, and properties of the scale. The measure was determined to hold promise as a research tool, but there appears to be little evidence that it can distinguish among the various types of pervasive developmental disorder or diagnosis Asperger syndrome specifically.     

Assessment Instruments for Asperger Syndrome

This review describes the current situation with regard to diagnostic instruments for Asperger syndrome. The paucity of such instruments, and the lack of adequate standardisation data amongst the few that do exist, represent a serious omission for both clinicians and researchers. The major problem limiting the development of effective diagnostic or screening instruments is the confusion inherent in ICD-10 and DSM-1V systems in differentiating autism from Asperger syndrome. In the absence of clear and clinically satisfactory diagnostic criteria, efforts to develop valid assessment instruments may be attempting to put the horse before the cart!     

Defining the Behavioral Phenotype of Asperger Syndrome

Asperger syndrome (AS) is characterized by social deficits and restricted interests in the absence of mental retardation and language delay. However, it is unclear to what extent the social deficits of AS differ from those of traditional autism. To address this issue, 58 subjects with AS were compared with 39 subjects with autism. Social deficits were classified according to Wing and Gould’s method. Forty-six (79%) subjects with AS were rated as active but odd, while 32 (82%) with autism were described as aloof and passive, while a few subjects showed mixed features. Thus, despite the overlap between AS and autism, subjects with AS showed a distinct pattern of social impairment. Implications of these findings are discussed.     

Creativity and Imagination in Autism and Asperger Syndrome

Three studies are reported that address the often described impoverished creativity in autism. Using the Torrance Creativity Tests, Experiment 1 found that children with autism and Asperger syndrome (AS) showed impairments. Experiment 2 tested two explanations of these results: the executive dysfunction and the imagination deficit hypotheses. Results supported both hypotheses. Children with autism and AS could generate possible novel changes to an object, though they generated fewer of these relative to controls. Furthermore, these were all reality-based, rather than imaginative. Experiment 3 extended this using a test of imaginative fluency. Children with autism and AS generated fewer suggestions involving attribution of animacy to foam shapes, compared to controls, instead generating reality-based suggestions of what the shapes could be. Although this is evidence of executive dysfunction, it does not directly account for why imaginative creativity is more difficult than reality-based creativity.     

Language Abilities of Children with Asperger Syndrome

Current diagnostic taxonomies (ICD-10, DSM-IV) emphasize normal acquisition of language in Asperger syndrome (AS). Although many linguistic sub-skills may be fairly normal in AS there are also contradictory findings. There are only few studies examining language skills of children with AS in detail. The aim of this study was to study language performance in children with AS and their age, sex and IQ matched controls. Children with AS had significantly lower scores in the subtest of Comprehension of Instructions. Results showed that although many linguistic skills may develop normally, comprehension of language may be affected in children with AS. The results suggest that receptive language processes should be studied in detail in children with AS.     

Autobiographical Memory and Social Problem-solving in Asperger Syndrome

Difficulties in social interaction are a central feature of Asperger syndrome. Effective social interaction involves the ability to solve interpersonal problems as and when they occur. Here we examined social problem-solving in a group of adults with Asperger syndrome and control group matched for age, gender and IQ. We also assessed autobiographical memory, on a cueing task and during social problem-solving, and examined the relationship between access to specific past experiences and social problem-solving ability. Results demonstrated a social problem-solving impairment in the Asperger group. Their solutions were less detailed, less effective and less extended in time. Autobiographical memory performance was also impaired with significantly longer latencies to retrieve specific memories and fewer specific memories retrieved in comparison to controls.     

Sleep in Children with Asperger Syndrome

The prevalence of sleep disturbances in 52 children with Asperger syndrome (AS) as compared with 61 healthy controls (all subjects aged 5–17 years) was investigated. Problems with sleep onset and maintenance, sleep-related fears, negative attitudes toward sleeping, and daytime somnolence were more frequent among children with AS than among controls. Short sleep duration (<9 h) was almost twofold (59% vs. 32%), and the risk for sleep onset problems more than fivefold (53% vs. 10%) more common in the AS group than in the control group. Child-reported sleeping problems were also more prevalent in the AS group than in controls (58% vs. 7%). The results suggest that sleep disturbances should be routinely evaluated in children with AS.     

Episodic Memory and Remembering in Adults with Asperger Syndrome

A group of adults with Asperger syndrome and an IQ-matched control group were compared in remember versus know recognition memory. Word frequency was also manipulated. Both groups showed superior recognition for low-frequency compared with high-frequency words, and in both groups this word frequency effect occurred in remembering, not in knowing. Nor did overall recognition differ between the two groups. However, recognition in the Asperger group was associated with less remembering, and more knowing, than in the control group. Since remembering reflects autonoetic consciousness, which is the hallmark of an episodic memory system, these results show that episodic memory is moderately impaired in individuals with Asperger syndrome even when overall recognition performance is not.     

Humor in Autism and Asperger Syndrome

Research has shown that individuals with autism and Asperger syndrome are impaired in humor appreciation, although anecdotal and parental reports provide some evidence to the contrary. This paper reviews the cognitive and affective processes involved in humor and recent neurological findings. It examines humor expression and understanding in autism and Asperger syndrome in the context of the main psychological theories (Theory of Mind, Executive Functions, Weak Central Coherence and Laterization models) and associated neural substrates. In the concluding sections, examples of humor displayed by individuals with autism/Asperger syndrome which appear to challenge the above theories are analyzed and areas for further research are suggested.     

A Family History Study of Asperger Syndrome

Asperger syndrome (AS) is a childhood-onset disorder often described as a mild variant of autism. Although classified as a distinct disorder in the DSM-IV, its overlap with autism continues to be a matter of ongoing debate. While the family genetic origins of autism are well established, few studies have investigated this topic in AS using current operational criteria. In this report, we examined the family psychiatric history of 58 subjects with AS diagnosed according to DSM-IV criteria (48 males; mean age 13.34; mean full scale IQ 104.87). All subjects had a history of mild autistic social deficits; focused special interests; normal level of intelligence; and an odd and often pedantic manner of speaking. None had a previous diagnosis of autism. Of the 58 subjects with Asperger syndrome, three had first degree relatives with AS; nine (15%) had a family history of schizophrenia; and 35 (60%) had a family history of depression. Of the 64 siblings, four had a diagnosis of AS and none of autism. Compared with a group of 39 subjects with normal intelligence autism (high functioning autism, HFA; 33 males; mean age 15.34; mean full scale IQ 85.89) subjects with AS were more likely to have relatives with depression; schizophrenia; and the broader autistic phenotype. Possible reasons for and implications of these findings are discussed.     

Conversational Behaviors in Youth with High-functioning ASD and Asperger Syndrome

Twenty-nine youth with autism spectrum disorders and 26 with typical development between 12 and 18 years of age were engaged in structured interviews (ADOS). The interviews were videotaped and rated for atypical conversational behaviors by trained raters, using the Pragmatic Rating Scale (Landa et al. Psychol Med 22:245–254, 1992). The ASD group was divided into AS and HFA/PDD-NOS subgroups. Significant differences were found among groups on approximately one-third of the PRS items. These items involved primarily the management of topics and information, reciprocity, intonation, and gaze management. The only differences to reach significance between the AS and HFA/PDD-NOS group were a greater tendency for overly formal speech on the part of the AS group, and more difficulty with gaze management on the part of the group with HFA/PDD-NOS. The implications of these findings for understanding and treating conversational deficits in ASD are discussed.     

Violent Crime in Asperger Syndrome: The Role of Psychiatric Comorbidity

Although several studies have suggested an association between violent crime and Asperger syndrome (AS), few have examined the underlying reasons. The aim of this review is to determine to what extent psychiatric factors contribute to offending behavior in this population. Online databases were used to identify relevant articles which were then cross-referenced with keyword searches for “violence,” “crime,” “murder,” “assault,” “rape,” and “sex offenses.” Most of the 17 publications which met the inclusion criteria were single case reports. Of the 37 cases described in these publications, 11 cases (29.7%) cases had a definite psychiatric disorder and 20 cases (54%) had a probable psychiatric disorder at the time of committing the crime. These findings underscore the role of psychiatric disorders in the occurrence of violent crime in persons with Asperger syndrome and highlight the need for their early diagnosis and treatment.     

Defining the Intellectual Profile of Asperger Syndrome: Comparison with High-Functioning Autism

Asperger syndrome (AS) is a disorder of early childhood characterized by autistic social deficits, subtle communication impairment, and excessive isolated interests. There is no history of language delay or of mental retardation. Despite its increasing popularity as a distinct condition, its diagnostic validity remains uncertain. It is still unclear to what extent AS differs from autism with normal intelligence sometimes referred to as high-functioning autism (HFA). However, some reports have suggested that persons with AS possess a distinct profile on tests of intelligence characterized by a high verbal IQ and a low performance IQ, whereas in most cases with HFA, the pattern is reversed. Since few studies have directly compared AS subjects with HFA controls using unmodified diagnostic criteria and standardized measures of assessment, in this report we compared 22 AS subjects with 12 HFA controls, matched on age, sex and level of intelligence. As a group, subjects with AS showed a higher verbal IQ and higher scores on information and vocabulary subtests than those with HFA. However, scores of several AS and HFA subjects showed a mixed pattern. Implications of these findings are discussed in the context of the validity of Asperger Syndrome.     

Social Skills Training for Adolescents with Asperger Syndrome and High-Functioning Autism

The effectiveness of a social skills training group for adolescents with Asperger syndrome and high-functioning autism (AS/HFA) was evaluated. Parents of six groups of adolescents (n = 46, 61% male, mean age 14.6) completed questionnaires immediately before and after the 12-week group. Parents and adolescents were surveyed regarding their experience with the group. Significant pre- to post-treatment gains were found on measures of both social competence and problem behaviors associated with AS/HFA. Effect sizes ranged from .34 to .72. Adolescents reported more perceived skill improvements than did parents. Parent-reported improvement suggests that social skills learned in group sessions generalize to settings outside the treatment group. Larger, controlled studies of social skills training groups would be valuable.     

Offending Behaviour in Adults with Asperger Syndrome

Considerable speculation is evident both within the scientific literature and popular media regarding possible links between Asperger syndrome and offending. A survey methodology that utilised quantitative data collection was employed to investigate the prevalence of offending behaviour amongst adults with Asperger Syndrome in a large geographical area of South Wales, UK; qualitative interviews were then conducted with a sub-sample of those identified. A small number of participants meeting the study criteria were identified. For those who had offended, their experience of the criminal justice system was essentially negative. Possible implications of the results were discussed.     

Differentiating Autism and Asperger Syndrome on the Basis of Language Delay or Impairment

Asperger syndrome (AS) is differentiated from high-functioning autism (HFA) largely on a history of “language delay.” This study examined “specific language impairment” as a predictor of outcome. Language skills of 19 children with AS and 45 with HFA were assessed at 4–6 years of age (Time 1) and 2 years later (Time 2). Children’s symptoms and functional outcome scores were assessed every 2 years (Times 3, 4, and 5) until ages 15–17 years old. Regression analysis revealed that specific language impairment at time 2 more often accounted for the greatest variation in outcome scores in adolescence than the standard diagnosis of AS versus HFA based on history of language delay. Diagnostic implications are discussed.     

Quantitative Assessment of Neuromotor Function in Adolescents with High Functioning Autism and Asperger Syndrome

Background: Motor impairment in children with Asperger Syndrome (AS) or High functioning autism (HFA) has been reported previously. This study presents results of a quantitative assessment of neuromotor skills in 14–22 year old HFA/AS. Methods: 16 HFA/AS and 16 IQ-matched controls were assessed by the Zurich Neuromotor Assessment (ZNA). Results: The HFA/AS group showed strongest impairments of dynamic balance skills and diadochokinesis. Motor abilities were associated with degree of social withdrawal in the full sample and severity of current autistic symptoms in the HFA/AS group. Conclusion: Similar motor patterns as in younger children were found in the older adolescents. The association of autistic symptoms with motor performance points towards an essential role of motor impairment in autism spectrum disorders.     

Processing of Affective Speech Prosody is Impaired in Asperger Syndrome

Many people with the diagnosis of Asperger syndrome (AS) show poorly developed skills in understanding emotional messages. The present study addressed discrimination of speech prosody in children with AS at neurophysiological level. Detection of affective prosody was investigated in one-word utterances as indexed by the N1 and the mismatch negativity (MMN) of auditory event-related potentials (ERPs). Data from fourteen boys with AS were compared with those for thirteen typically developed boys. These results suggest atypical neural responses to affective prosody in children with AS and their fathers, especially over the RH, and that this impairment can already be seen at low-level information processes. Our results provide evidence for familial patterns of abnormal auditory brain reactions to prosodic features of speech.