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)