THE ADHD SPECTRUM
Professor Hans-Christoph SteinhausenDepartment of Child and Adolescent Psychiatry
University of Zurich,Switzerland
The Social Brain 2Glasgow 3-2006
Inattention Hyperactivity Impulsivity
DefinitionCore symptoms
ClassificationDimensional approach
• ADHD...
• … is not like tuberculosis or epilepsy (categorical with clear symptoms for diagnosis)
• … is rather like hypertension or being overweight (dimensional with spectrum of symptoms)
One can have more or less of it; the borders blur; however, its classification (ICD-10 or DSM-IV) is categorical
Epidemiology
Prevalence rates according to criteria
• DSM-III-R: 3 - 11 per cent• DSM-IV: 8 - 18 per cent• ICD-10: (?) 2 per cent
Aetiology / Neuroanatomy
• Smaller brain (~4%): right frontal lobe (~8%)
• Smaller basal ganglia (~6%) normalisation (~18 years)
• Smaller cerebellum (12%) more pronounced (~18 years)
• Volumetric differences:
manifest early (~6 years)
correlate with ADHD severity
are irrespective of medication status
are irrespective of comorbidities
Age (years)
900
1000
1100
5 7 9 11 13 15 17 19 21
ml
Control malesADHD malesControl femalesADHD females
Controls > ADHD P<0.003
Total brain volume
•ADHD: activity remains reduced (less attention, van Leeuwen et al 1998) • younger age: activity is stronger (increased attentional demand)
y8 10 12
P300 µV
Cue P300: longitudinal
Cue P300: posterior sources
Aetiology / NeurophysiologyEEG based: ADHD maturational lag
ADHDn=12
controlsn=11
Year 1 / Age11
Year 2 /Age12
ADHDt-maps:ADHD -controls
Maturational Lagt-maps: year 1 - year 2
+7µV/ t
-7µV/ t
^ ^ ^
^ ^ ^
^ ^ ^
(Manova: ADHD X cue/distractor p<.01, year p<.05)
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• Analyse data• Prepare for response
• Noradrenaline• Dopamine
• Anterior• (eg frontal)
• Disengage from stimuli• Change focus to new stimuli• Engage attention to new stimuli
• Noradrenaline• Posterior• (eg parietal)
• Activity• Neurotransmitterinvolved
• Attentionalsystems
Regions rich in dopamine (DA) and noradrenaline (NA) are consistently
implicated
Aetiology / Neurochemistry
ADHD involves dysfunction in a widely distributed neural network
AetiologyNeuropsychology
Anteriorattentionalsystem
Frontal lobeStriatum
Posteriorattentionalsystem
CerebellumAnterior Attention System
Posterior Attention System
Inhibition (motor, cognitive and emotional)
Planning
Working memory
Speech fluency
Selective and sustained attention
Cognitive flexibility or interference control
These findings are not specific to ADHD
Aetiology / NeuropsychologyDisturbance of executive functioning
Aetiology / Genetics
Twin Studies
• Correlations and concordance rates for ADHD-traits and -symptoms are higher in MZ than in DZ.
• Heritability estimates range from 0.39 to 0.91
• Parental (maternal) contrast effects account for the low DZ correlations.
Aetiology / Genetics
Molecular Genetics
• Associations of ADHD with variations in certain genes, e.g.dopamine transporter gene DAT1 (positive and negative reports) and dopamine receptor genesDRD-4 and -5 (positive and negative reports)
• Significant associations with ADHD but small effect sizes (not more than 5 per cent of the variance)
Aetiology / Genetics
Clinical Implications
• ADHD is highly heritable
• Most children with DNA variants do not have ADHD
• Most children with ADHD do not have the known DNA variants
• Further work is needed before results can be incorporated into clinical practice
Risk factorsRisk factors
Genetic dispositionGenetic disposition
Acquired biological factorsAcquired biological factors
Adverse conditions in family/ school
Adverse conditions in family/ school
Altered neuronal networksAltered neuronal networks
Altered self-regulationAltered self-regulation
Inattention,Hyperactivity, Impulsivity
Inattention,Hyperactivity, Impulsivity
Negative interactions with caregivers
Negative interactions with caregivers
Associated disorders/ problemsAssociated disorders/ problems
ProcessesProcesses
Neuroanatomy• chemistry
• physiology
Neuroanatomy• chemistry
• physiology
Neuro-psychology
Neuro-psychology
BehaviourBehaviour
InteractionsInteractions
Coexisting
problems
Coexisting
problems
LevelsLevels
Döpfner et al 2002
Aetiology / Integrated Framework
Symptom domains Inattention Hyperactivity Impulsivity
Symptom domains Inattention Hyperactivity Impulsivity
Psychiatric comorbidities
Disruptive behavioural disorders (conduct disorder and oppositional defiant disorder)
Anxiety and mood disorders
Psychiatric comorbidities
Disruptive behavioural disorders (conduct disorder and oppositional defiant disorder)
Anxiety and mood disorders
Lead to+
Functional impairmentsSelf Low self-esteem Accidents and injuries Smoking/ substance abuse DelinquencySchool/ work Academic difficulties/
underachievement Employment difficultiesHome Family stress Parenting difficultiesSocial Poor peer relationships Socialisation deficit Relationship difficulties
Functional impairmentsSelf Low self-esteem Accidents and injuries Smoking/ substance abuse DelinquencySchool/ work Academic difficulties/
underachievement Employment difficultiesHome Family stress Parenting difficultiesSocial Poor peer relationships Socialisation deficit Relationship difficulties
Clinical Picture Psychosocial impairments
Over 85% of patients have at least one comorbidity and approximately 60% of patients have at least two comorbidities
Comorbidity
• Autism spectrum disorders, Mental retardation
Infrequent
• Tic disorders, Depressive disorder
Less frequent (up to 20%)
• Specific learning disorders, Anxiety disorder, Developmental coordination disorder
Frequent (up to 50%)
• Oppositional defiant or conduct disorder
Very frequent (more than 50%)
Clinical Assessment
• Interviews with parents and child
• Behavioural observation
• Questionnaires and rating scales
• Neuropsychological testing
• Physical examination and neuromotor testing
• Laboratory tests
• Differential diagnosis
Multidimensional approach
TreatmentInterventions
Patient-focusedPatient-focused
Parent-focusedParent-focused
School-focusedSchool-focused
Cognitive behaviour therapyCognitive behaviour therapy
PsychopharmacotherapyPsychopharmacotherapy
PsychoeducationPsychoeducation
PsychoeducationPsychoeducation
Behavioural interventionsBehavioural interventions
Parent trainingParent training
PsychoeducationPsychoeducation
Clinical Course Conclusion
• ADHD is a chronic disorder, the clinical picture changes over the lifespan of the patient
• Diagnostics and treatment must be adapted throughout the patient‘s lifespan:
• Preschoolers - early intervention, behavioural methods preferred
• Schoolchildren - combination of drug and behavioural therapy
• Adolescents/adults - treatment modification needed (associated problems)