Download Autistic Disorder

Autistic Disorder:
Diagnosis and Treatment
• Diagnosis
• Epidemiology
• Etiology
• Treatment
Diagnosis of Autism
• Triad of symptom clusters repeatedly found:
– Impaired social interactions
– Abnormal language development
– Restricted and repetitive patterns of behaviour
Social Impairments
• marked impairments in the use of multiple nonverbal
behaviors such as eye-to-eye gaze, facial expression,
body posture, and gestures to regulate social interaction
• failure to develop peer relationships appropriate to
developmental level
• a lack of spontaneous seeking to share enjoyment,
interests, or achievements with other people
• lack of social or emotional reciprocity
Language Impairments
• delay in, or total lack of, the development of spoken
language
• in individuals with adequate speech, marked impairment
in the ability to initiate or sustain a conversation with
others
• stereotyped and repetitive use of language or
idiosyncratic language
• lack of varied, spontaneous make-believe play or social
imitative play appropriate to developmental level
Behavioural Impairments
• encompassing preoccupation with one or more stereotyped
and restricted patterns of interest that is abnormal either in
intensity or focus
• apparently inflexible adherence to specific, nonfunctional
routines or rituals
• stereotyped and repetitive motor mannerisms
• persistent preoccupation with parts of objects
Diagnosis of
Pervasive Developmental Disorders
a)
Autism
-at least 6 symptoms, including 2 from social domain, 1
from communication area, and 1 from behavioural domain
b)
Asperger’s Disorder
-at least 3 symptoms, including 2 from social realm and 1
from behavioural realm with “no clinically significant
delays in language or cognitive development”
c)
Pervasive Developmental Disorder Not Otherwise
Specified
- ??
Other Pervasive
Developmental Disorders
• Rett’s Syndrome
• Childhood Disintegrative Disorder
• Diagnosis
• Epidemiology
• Etiology
• Treatment
Epidemiology of Autism
• Autism : ~1/1,000
• All pervasive developmental disorders: ~1/300
• Male:female ratio: 4:1 (but approaches 1:1 as IQ drops)
Increasing Prevalence of Autism
Epidemiology of Autism
• 2/3 to 3/4 have intellectual disabilities
• 1/3 develop seizures, usually in adolescence
• ~5% of patients have a known chromosomal abnormality
• Diagnosis
• Epidemiology
• Etiology
– Neurobiology
– Genetics
– Psychological Factors
– Environmental factors
• Treatment
Neurobiology of Autism
• Considered a “neurodevelopmental disorder” (i.e., caused by
abnormal development of the brain)
• Although many (perhaps most) brain regions have been
implicated in autism, two findings stand out
• Brain imaging
– Brain size
– Corpus callosum
– Functional brain imaging
“Physically, the 11 children were essentially
normal. Five had relatively large heads.”
-Kanner, 1943
Increased Brain Size In Autism
• Several studies suggest patients have increased head
circumference, and up to 20% of patients may have head
circumferences above the 97th percentile
• Autopsy studies also suggest that some patients have
increased brain weight
• Most MRI studies of the brain in autism in the past 10 years
have reported increased brain volume in patients
Increased Brain Size In Autism
• While it appears that patients with autism have enlarged
brain size, at least at some point in their life, the timing and
persistence of this increase is uncertain
• While some suggest that it persists into adulthood, others
hypothesize that an initial period of rapid brain growth is
followed by a period of slowed cerebral growth, so that by
adolescence, brain size is no different from unaffected
people
Brain Size in Preschoolers with Autism
Total Cerebral Volume (mL)
1500
1400
Patients
Controls
p<0.001
p<0.001
Courchesne, 2001
Sparks, 2001
1300
1200
1100
1000
Brain Size In Older Children,
Adolescents, And Adults with Autism
Total Cerebral Volume (mL)
1600
Controls
1500
1400
p=0.03
Patients
p=0.03
p=0.1
p=0.4
1300
1200
1100
1000
Courchesne, 2001
Aylward, 2002
Hardan, 2001
Piven, 1996
• Brain imaging
– Brain size
– Corpus callosum
– Functional brain imaging
Corpus Callosum in Autism
Author
Result
Filipek et al., 1992
no difference
Egaas et al., 1995
(posterior third)
Piven et al., 1997
(middle and posterior)
Manes et al., 1999
(total and body)
Hardan et al., 2000
(anterior; trend to total cc)
Boger-Megiddo et al., 2003
Vidal et al., 2003
(total)
(total, anterior, and posterior)
Corpus Callosum in Autism:
Shape Differences
Vidal et al., 2003
Corpus Callosum and Cerebral
Lateralization in Autism
• Given its role in cerebral lateralization, the relative reduction
of the size of the corpus callosum suggests aberrant
lateralization of cerebral function in autism
• Consistent with this, several studies have found increased
rates of left- and mixed-handedness in autism as well as
increased rates of right-hemisphere dominance for language
• Two MRI studies (Herbert et al., 2002; Rojas et al., 2002)
have reported reduced or reversed patters of asymmetry in
language-related brain regions in patients with autism
• Brain imaging
– Brain size
– Corpus callosum
– Functional brain imaging
fMRI of Facial Processing in Autism
• Abnormalities of facial processing in autism have been
consistently reported in clinical studies
• In three studies of facial processing using fMRI, patients
have not used brain regions typically involved in this task
but rather have used regions more typically used for object
recognition
• Diagnosis
• Epidemiology
• Etiology
– Neurobiology
– Genetics
– Psychological Factors
– Environmental factors
• Treatment
Genetics of Autism
• 5% of patients have gross cytogenetic abnormalities
• Sibling recurrence rate is 2% to 5%
• Heritability of autism is about 90%
• “Unaffected” relatives have increased rates of social,
language, and behavioural problems
• Diagnosis
• Epidemiology
• Etiology
– Neurobiology
– Genetics
– Psychological Factors
– Environmental factors
• Treatment
Psychological Factors in Autism
• Main deficit in autism is controversial
• Predominant theory is that patients with autism lack a
“theory of mind” – the ability to understand other people’s
thought processes and to make inferences about the thoughts
of others
Comparison of Theory of Mind and
Comparison Test
Theory of Mind in Autism
• In addition to performing more poorly on tests of Theory of
Mind, subjects with autism also appear to activate brain
regions thought to be involved in “mentalizing” less than
controls (amygdala and prefrontal cortex)
• Diagnosis
• Epidemiology
• Etiology
– Neurobiology
– Genetics
– Psychological Factors
– Environmental factors
• Treatment
Environmental Factors in Autism
• No proven link between environmental factors and autism,
although many suggested
• Much recent attention on MMR vaccine, but large scale
epidemiological studies suggest no relationship
• Diagnosis
• Epidemiology
• Etiology
• Treatment
– medication
– psychosocial
Pharmacotherapy of Autism
• There are no treatments for autism per se
• Treatment is therefore aimed at reduction of behaviours
which interfere with the individual’s daily functioning
• Goal of medication should be to enhance other treatments
(behaviour modification, education, speech therapy,…)
Interfering Behaviours Commonly
Seen in Autism
• Aggression
• Inattention and hyperactivity
• Anxiety/Ritualistic behaviour
• Sleep Disturbances
• Sensory Hypersensitivity
Treatment of Aggression in Autism
• Aggresssion, to others, to self, and to property, is a common
problem in autism
• Commonly associated with frustration and so probably best
viewed as a problem of impulse control
Interfering Behaviours Commonly
Seen in Autism
• Aggression
• Inattention and hyperactivity
• Anxiety/Ritualistic behaviour
• Sleep Disturbances
• Sensory Hypersensitivity
Inattention and Hyperactivity
in Autism
• Common comorbid condition for pervasive developmental
disorders and mental retardation (10% to 20% of children
with MR have ADHD)
Interfering Behaviours Commonly
Seen in Autism
• Aggression
• Inattention and hyperactivity
• Anxiety/Ritualistic behaviour
• Sleep Disturbances
• Sensory Hypersensitivity
Anxiety in Autism
• Can present as:
– repetitive and ritualistic behaviour
– phobias
– difficulty with unpredictability
– social withdrawal
• Can be associated with aggression
Alternative Therapies in Autism
•
•
•
•
•
•
B-vitamins
Vitamin A
Vitamin C
DMG (dimethylglycine)
DMSA
Secretin
• Essentially all are lacking solid evidence for effectiveness
• Medications should NOT be viewed as a treatment for
developmental disorders
• They should be viewed as a treatment which can make other
interventions (education, behaviour therapy, speech therapy,
etc) more effective by reducing behaviours which interfere
with these therapies
Psychosocial Treatments in Autism
• Social skills training
• Occupational therapy
• Speech therapy