autism 1

The Dx and Classification of ASDs: Progress and PitfallsProf. Peter Szatmari

1The screen versions of these slides have full details of copyright and acknowledgements

The Dx and Classification of ASDs: Progress and Pitfalls

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Peter Szatmari MDOfford Centre for Child Studies

McMaster University and Childrens Hospital

Objectives

Been 15 years since DSM IV

To review the current classification and diagnosis in the ASDs; are we farther ahead?

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Point out subtleties in diagnosis and some suggestions for future directions

Two cases: Johnny

5 y/o, in sk, speech delay

Socially isolated, avoids teachers and peers

Prefers to play by himself

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Little language

Lines up the toys, plays with string, stares at the blinds

Receptive language delay, good block design on IQ test



Freddie

9 y/o, ADHD, in residential Rx

Isolated but obsessed with school mate

Aggressive, anxious about electrical outlets

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Disjointed conversation about heating systems

Imaginary companions, cleaning fluids

Spoke on time, normal IQ but LD

Two cases (cont)

Do they have the same or a different disorder?

How do we classify these children?

Different symptoms and developmental level

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But similar impairments and relative skills; on a spectrum?

History of terms

Kanner and infantile autism (1943)

In North America

Childhood psychosis or schizophrenia

Brain damage and mental retardation

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Brain damage and mental retardation

Atypical development

Asperger syndrome (1944)

Pervasive developmental disorders (1990)

Autism spectrum disorders (L. Wing)



Types of ASD

Autistic disorder

Asperger disorder

PDDNOS or atypical autism

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Retts and disintegrative disorders are not ASDs but they are PDDs in DSM-IV

ASDs common elements

Impairments in reciprocal social interaction

Impairments in communication

Pattern of RSB and/or circumscribed interests

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Age of onset



DSM-IV criteria for autism

3 domains; reciprocal social interaction, verbal and non-verbal communication, and repetitive behaviours

12 ibl b h i (4 i h)

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12 possible behaviours (4 in each)

Pattern of at least 2-1-1, 6 in total

Onset before 36 months

How good are these criteria?

DSM III (1980): too narrow

DSM IIIR (1987): too broad

DSM IV (1994): just about right

A ti ASD d

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Autism vs. non-ASD: very good

Poorer in the very young, very low functioning, higher functioning and adults

In those without data at 4-6 years of age

Reliability varies with expertise

Differential diagnosis

General learning disability (intellectual disability)

Specific language delays

ADHD

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Anxiety disorders



Common mistakes in diagnosis

Mental age



Clinical features of AS

Impairments in social reciprocity

Poor conversation skills

Intense and unusual preoccupations

Ab f li i ll i ifi t l

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Absence of clinically significant language and cognitive delay

Motor clumsiness?

Later age of onset?

Different uses of AS

Verbal adults with autism

A form of high functioning autism

PDDNOS and atypical autism

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A separate disorder or

Autism without the language disorder?

DSM-IV criteria for AS

Same criteria for autism in social and repetitive activity domains

Absence of language and cognitive delay

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Does not meet criteria of autism



Problems with DSM-IV criteria

No mention of communication impairments (importance of differentiating language and communication)

Criteria for absence of language and cognitive delay?

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Hierarchical approach

Most AS meet criteria for autism

No mention of age of onset or motor problems

Is AS a valid disorder? clinical differences from autism

Fewer/less severe social impairments

Better language skills

Fewer motor stereotypies and self-stimulatory behaviour

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More rituals, insistence on sameness

Problem

Explained by initial differences in IQ and language?

Differences from autism: etiology

AS and autism run in the same families

Differences in Gender

Epilepsy

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Brain imaging

Again explained by IQ?

Two systematic reviews: differences in severity not type nor etiology

BUT: is this comparing the unknown with the less well known?



What do we know about outcome of autism?

Poorer outcome if intellectual disability present

And if no useful language before 6 years of age

Does AS have a better outcome compared to autism

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without ID (HFA)

A few retrospective studies of outcome

One prospective study

Design of follow up study

HFA and AS seen at 4-6, 6-8, 9-12, 14-17

HFA: IQ>70, met DSM-IV criteria by ADI

AS: PDD symptoms in each domain but talk in phrases

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by 36 months and IQ>70 (most met ADI criteria for autism)

Measures of symptoms (ABC) and adaptive functioning (VABS) over time

Vineland Communication domain

Com

mun

icat

ion

Scor

e

130

120

110

100

90

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Time3.002.001.00.00M

ean

Vine

land

CR

aw 90

80

70

60

50

Group

Asperger

Autism

4-6 6-8 9-12 14-17



Vineland Socialization domain

ocia

lizat

ion

Scor

e

100

90

80

25Time

3.002.001.00.00Mea

n Vi

nela

nd S

o 70

60

50

40

GroupAsperger

Autism

Autism behaviour checklistsensory domain

nsor

y Sc

ore

9

8

7

6

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3.002.001.00.00

Mea

n AB

C S

en 6

5

4

3

2

Time

GroupAsperger

Autism

Sub-groups within autism pathway?

HFA no SLI at 6 ys

(N=18)

AS

(N=19)

Individuals with HFA are not a homogenous group

2787 (16)93 (16)Time 4

56 (11)66 (11)Time 1PV Soc

115 (9)118 (7)Time 4

74 (19)82 (12)Time 1PV Comm



Conclusions

Compared to those with HF autism, AS children have better long term outcomes

Differences are large

Developmental trajectories are parallel: not coming

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Developmental trajectories are parallel: not coming together not growing apart

Among HF ASD: presence/absence of SLI at 6y/o is most important predictor

AS and HF autism are both same and different on outcome!

PDDNOS in DSM-IV

Has social impairment

But not the communication impairment

Or no evidence of RRSB

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Or later age of onset

Or all three of the above

But does not meet criteria for AS

The possibilities are numerous!

Prevalence rates per 10,000

Autism NOS Total

Y-A 34 -- (76)

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( )

C & F 23 37 60

Baird 39 77 116

CDC 66

Fombonne 22 43 65



Proportion of autism to total ASD

Autism/Total

Y-A 34/76=.45

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C & F 23/60=.38

Baird 39/116=.34

Fombonne 22/65=.39

Changing ratio of ID

Roughly 60% of ASD are PDDNOS in epidemiological studies

Typically, ratio of ID to normal IQ: 3 to 1 (75% to 25%)

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But this refers to autism

What are the rates of ID in autism and non-autism ASD?

Is PDDNOS valid? differences from autism

1. Lower functioning (autism-like but too low functioning to meet 6/12)

2. Higher functioning group (looks like AS b t h d l )

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but speech delay)

Fewer RSB? later age of onset? more comorbidity?

Most studies comparing autism and NOS do not R/O AS!



Problems with criteria for PDDNOS

Very poor agreement among experts (Mahoney et al., 1998)

In young or high risk: very poor stability

Either

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PDDNOS to non-ASD

Or PDDNOS to autism/AS

A diagnosis to be avoided?

Problems with diagnostic system

Differentiation of autism from non-ASD is excellent

Differentiation among ASD is very poor

AS hardly exists: hierarchy rule

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PDDNOS very poor reliability and unstable

No significant independent etiologic correlates differentiate the groups

Differences between HFA and AS on outcome

Hierarchical approach to DX

Does the child have ASD?

If IQ below 70 = autism with ID (complex autism)

Is IQ above 70? HF ASD

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Is there absence of speech delay (and SLI)?

If yes: Asperger syndrome

If no: does child meet criteria for HF autism?

If no: will child meet criteria for PDDNOS?



ASD multiple spectra model

Social-communication

RRSAS

SLINOS

HFA

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Complex autism

HFA

We only know anything by knowing it as distinguished from something else

A thing is only seen to be what it is by contrast with what it is not

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John Stuart Mills Examination of Sir William Hamiltons Philosophy (1865)

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