1. AUTISM SPECTRUM DISORDERS AND DEVELOPMENTAL DYSPHASIA
1.2. Clinical characteristics and classification
The diagnostic criteria of classical autism are shown in Table 1. In addition, mental retardation (MR) is present in 40-75% (Rutter 1979) and epilepsy in 25-30% of cases (Volkmar and Nelson 1990). Only about 10% of individuals with autism are able to live and function relatively independently (Lainhart and Piven 1995), and most require lifelong assistance. The two strongest predictions of the clinical outcome later on are the IQ and the level of language development at the age of five years (Bailey et al. 1996).
Individuals with a diagnosis of autism have a recognisable medical syndrome in ~10-15% of the cases (Folstein and Rosen-Sheidley 2001). These known medical conditions include e.g.
phenylketonuria, Fragile-X syndrome, tuberculosis sclerosis, neurofibromatosis 1, Rett syndrome, Down syndrome, Angelman’s syndrome, cerebral palsy, Moebius syndrome and Cornelia de Lange’s syndrome. Environmental factors reported to cause autism are infectious diseases occurring prenatally or after birth (rubella, herpes simplex virus encephalitis) and some toxic syndromes (fetal alcohol syndrome, fetal cocaine or valproate exposure, lead poisoning and thalidomide embryopathy).
The differential diagnosis of autism include e.g. other forms of PDD, developmental language disorders, mental retardation and deafness (Smalley et al. 1992; Rutter et al. 1994).
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Table 1.
DIAGNOSTIC CRITERIA FOR AUTISM DISORDER (ICD-10) (WHO 1993)
A. A total of six (or more) items from 1,2 and 3 with at least two from 1, and one each from 2 and 3:
1. Qualitative impairment in social interaction, as manifested by at least two of the following:
a. marked impairment in the use of multiple non-verbal behaviours, such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction b. failure to develop peer relationships appropriate to developmental level
c. a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g. by a lack of showing, bringing, or pointing out objects of interest) d. lack of social or emotional reciprocity
2. Qualitative impairment in communication as manifested by at least one of the following:
a. a delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative models of communication such as gesture or mime)
b. in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
c. stereotyped and repetitive use of language or idiosyncratic language
d. lack of varied, spontaneous make-believe play, or social imitative play, appropriate to developmental level
3. Restricted repetitive and stereotyped patterns of behaviour, interests and activities, as manifested by at least one of the following:
a. encompassing preoccupation with one or more stereotyped and restricted patterns of interest, which is abnormal either in intensity or focus
b. apparently inflexible adherence to specific, non-functional routines or rituals c. stereotyped and repetitive motor mannerisms (e.g. hand- or finger-flapping or -twisting, or complex whole-body movements)
d. persistent preoccupation with parts of objects
B. Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years:
1. Social interaction.
2. Language as used in social communication 3. Symbolic or imaginative play.
C. The disturbance is not better accounted for by Rett’s disorder or childhood disintegrative disorder.
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1.2.2. Asperger Syndrome
The different diagnostic criteria of AS currently in use are shown in Table 3. AS can be distinguished from autism and PDD-NOS on the basis of higher verbal IQs, higher rates of the disorder in the first degree relatives and different patterns of co-morbidity, especially depression (Volkmar et al. 2000).
Recently, a novel multidimensional system to classify autism spectrum disorders has been proposed (Szatmari 2000) that emphasises the developmental process of the disease. The key factor in this process is the timing of the development of fluent language that will canalise the further development to a certain level of functioning. PDD subtypes might be classified as different developmental pathways that differentiate at certain time points, rather than separate entities. This means that the diagnostic criteria need not be changed, but focus should be emphasised on the genetic, epigenetic and environmental factors that move the child from one PDD pathway to another.
1.2.3. Developmental dysphasia
Under ICD-10 criteria the disorder is classified either as expressive type of language disorder (F80.1) or mixed receptive-expressive type of language disorder (F80.2) (World Health Organization 1993). The diagnostic criteria are shown in Table 2.
Table 2.
DIAGNOSTIC CRITERIA FOR DEVELOMENTAL LANGUAGE DISORDERS (ICD-10) (WHO 1993)
EXPRESSIVE LANGUAGE DISORDER (F80.1)
A. Symptoms including markedly limited vocabulary, making errors in tense, having difficulties in recalling words or producing sentences with developmentally appropriate length or complexity
B. The difficulties with expressive language interfere with academic or occupational achievement or with social communication.
C. Criteria are not met for mixed Receptive-expressive language disorder or for PDD D. If mental retardation, a speech-motor or sensory deficit, or environmental deprivation
is present, the language difficulties are in excess of those usually associated with these problems.
MIXED RECEPTIVE-EXPRESSIVE LANGUAGE DISORDER (F80.2)
A. Symptoms include those for Expressive language disorder as well as difficulties in understanding words, sentences, or specific types of words such as spatial terms.
B. The difficulties with mixed receptive-expressive language interfere with academic or occupational achievement or with social communication.
C. Criteria are not met for PDD.
D. If mental retardation, a speech-motor or sensory deficit, or environmental deprivation is present, the language difficulties are in excess of those usually associated with these problems.
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Table 3. The clinical criteria for AS.
CLINICAL FEATURE ASPERGER
(1944; 1979) WING 1981 GILLBERG &
GILLBERG
(1989)
TANTUM
(1988)
SZATMARI
(1989)
ICD-10 (WHO, 1993)
DSM-IV (APA, 1994)
Social impairment Yes Yes Yes Yes Yes Yes Yes
Poor nonverbal communication Yes Yes Yes Yes Yes Yes Yes
Poor empathy Yes Yes Yes Yes Yes Yes Yes
Failure to develop friendships Yes Yes Yes Yes (implied) Yes Yes Yes Language/
Communication
Poor prosody and pragmatics Yes Yes Yes Yes Yes Not stated Not stated Idiosyncratic language Yes Yes Not stated Not stated Yes Not stated Not stated Impoverished imaginative play Yes Yes Not stated Not stated Not stated Yes Not stated All-absorbing interest Yes Yes Yes Yes Not stated Yes Often Motor clumsiness Yes Yes Yes Yes Not stated Yes (common) Often Onset (0-3 years)
Speech delays/
Deviance
No May be present May be present
Not stated Not stated No No Cognitive delays No May be present Not stated Not stated Not stated No No Motor delays Yes Sometimes Not stated Not stated Not stated May be
present
May be present Exclusion of autism Yes (1979) No No No Yes Yes Yes Mental retardation No May be present Not stated Not stated Not stated Not stated Not stated
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Table adapted from Volkmar and Klin, 2001