ADHD - Aetiological theories, Clinical Assessment

What are biological theories for ADHD?

Genetic

Neurotransmitter dysregulation

Neuroanatomical abnormalities

Hypoarousal theories

Genetic theories for ADHD

ADHD symptomology or predisposition to hyperactivity is inherited

Supported by twin, adoptive, family studies

Environmental factors are not causal but contributive - expression, severity, course

Specific gene studies focus on dopaminergic and serotonergic systems

Neurotransmitter dysregulation theories for ADHD

Dysregulation of the dopaminergic and serotonergic systems, underpinned by observed stimulant medication effects

Neuroanatomical abnormalities theories for ADHD

Structural or functional neurological deficits

Delayed brain growth

Dysfunction in prefrontal lobes

• Involved in inhibition, EFs

Differences in neural structures

• PFC, corpus callosum, caudate nucleus

Hypoarousal theories for ADHD

Underarousal - attentional difficulties relate to being less responsive to stimuli

Support comes from psychophysiological studies and EEG

What are environmental and systemic risk factors for ADHD?

Pre- and peri-natal factors

Nutritional deficiencies

PArental psychopathology

Intrusive caregiver behaviour

Abuse and neglect

Exposure to significant family conflict/marital distress and/or domestic violence

deprivation

Pre and peri-natal factors for ADHD

Maternal smoking

Alcohol and drug use in pregnancy

High maternal stress

Anoxia at birth

Prematurity or low birth weight

What are neuropsychological theories for ADHD?

ADHD arises from deficits in specific neuropsychological and/or cognitive processes

• Executive function

• Motivational dysfunction

• Delay aversion

• Response variability

What is the Executive dysfunction and self-regulation hypothesis from Barkley?

ADHD symptoms reflect deficits in EF critical for adaptation and include:

1. Self-awreness

2. Behavioural inhibition

3. Non-verbal working memory

4. Verbal working memory

5. Self regulation of affect, arousal, and motivation, and

6. Self-directed play

Give Wilcutt’s summary for the Executive function theory of ADHD

Several theories implicate EFs (cogntiive processes involved in problem solving and decision making)

EFs involved include:

• response inhibition

• Verbal and spatial memory

• Set shifting

• Planning

• Interreference control

The Motivational dysfunction theory for ADHD proposes that ADHD symptoms arise from what?

Differences in which rewards or punishments are responded to

The Delay Aversion theory rpoposes that individuals with ADHD…

Find the experience of delay difficult to tolerate/aversive — resulting in behavior to minimise delay

What is the response variability theory for ADHD?

Individuals with ADHD are slower and more variable in responses

What is a summary of the neuropsychological theories, including weaknesses?

ADHD does appear to be associated with:

• Weak inhibitory control

• Delay aversion

• Response variability

• Processing speed

• Working memory

However, not all children show uniform deficits on cognitive measures, including across executive functions

What is the Neurodiversity theory for ADHD? What are 3 key assumptions?

Children w/ ADHD have neurodivergent personal characteristics which only constitute a disability within context of demands of a neurotypical world

Assumptions:

1. ADHD symptomology reflects normal variation in the population - “differences” not deficits

2. All people, including the neurodivergent, have a right to be treated with respect and dignity

3. A good quality of life for people with ADHD may be very different from a good quality of life for neurotypical people

Aetiological theories for ADHD: Summary (4 points)

• Single factor theiries unlikely to be able to explain the complex, heterogenous population who meet ADHD criteria

• Probable that variety of biological and psychosocial factors interact in complex ways to result in ADHD

• Likely several neuropsychological mechanisms underpinning symptomatology, particularly those invovled in regulating cognitive and motor responses

• ADHD symptomatology is probably partially maintained and exacerbated by problematic relationships with family, peers, school

How might ADHD present in infancy? Diagnostic issues?

Temperamental risk factors; high reactivity + low regulation; irritability

May also give rise to harsh, inconsistent parenting

No reliable or valid method to identify

How might ADHD present in the toddler/preschool years? Diagnostic issues?

Excessive motor activity/hyperactivity

Difficult to calm/temper tantrums/reactive aggression

Some emerging peer relational difficulties

Non-compliance

Concerns re. school readiness

High accidental injury rate

NOTE: high risk of false positive due to normative developmental trajectories

How might ADHD present in early primary school? Relationship to diagnosis?

• Evidence of inattention becomes more apparent; distractible

• Hyperactivity and impulsivity persist; difficulty sitting still; high energy

• Oppositional behaviour may develop

• Struggle to follow directions or comply with rules and routines

• Academic problems

• Difficulty with social interactions - may be disruptive/intrusive

• Self-esteem issues

• Period where most childhood cases come to attention

How might ADHD present in adolescence? Relationship to symptoms?

Hyperactivity may reduce, while feelings of restlessness or impatience remain

Inattention, disorganisation, impulsivity persists

Elevated risk of delinquency and substance misuse (boys espec)

Self-injury / suicidal behaviour (girls espec)

Adolescent psychopathology/comorbidity

Academic problems

Difficulty with social interactions

Self-esteem issues

Potential for symptom exacerbation

In adolescence, boys are at elevated risk for ______, while girls are at elevated risk for _____.

Deliquency/substance misuse; self-injury and suicidal behaviour

What might account for late onset/adolescence symptoms of ADHD?

a. subthreshold symptoms of psychiatric/behavioural problems that take the form of ADHD in adolescence

b. Children whose vulnerability to ADHD is managed w/out impact due to strengths in IQ/language/EF, or mitigated by protective environmental factors, becomes increasingly difficult to manage when supports reduce or demands increase

c. Trauma or other adversity manifests as ADHD

In adulthood, ______ remain. While ______ diminishes, ______ can continue to be problematic.

Inattention/restlessness; Hyperactivity; impulsivity

How might ADHD present difficulties in adulthood? (9)

Mental/internal restlessness; unfocussed thoughts or mental activity, difficulty relaxing

Emotional lability / self-regulation or impulse control problems

Organisational or problem-solving difficulties

Occupational/vocational/academic failure

Self-esteem issues

Relationship and interpersonal problems

Injury/accidents

Substance abuse

Sleep disturbance

Can ADHD be outgrown?

No but symptomatology changes

How do specifiers of ADHD relate to adulthood presentation?

Inattention more common

Combined and hyperactive/impulsive presentation associated with higher rates of substance abuse, antisocial behavior

What did Sibley et al., challenge and find?

Challenged the idea half of cases remit in adulthood

Only 9.1% recovered, 10.8% had stable persistence

Rest had fluctuating course

90% of people w/ childhood ADHD experience symptoms, impairments to young adulthood

Child-onset ADHD is a chronic, but waxing and waning disorder w/ periods of remission that are temporary

What are considerations of ADHD assessment?

No biological markers

Neurological measures incl neuroimaging not routine

Dx based on comprehensive clinic assessment

Treatment, management multimodal

Treatment and management of ADHD is guided by what?

• Individual case conceptualisation

• Possible environmental impacts and co-occurring conditions

• Age and stage of development

What are questions we might ask about in a clinical assessment for ADHD?

Concerns? Reported symptoms

Relationship to developmental stage

Diagnosis and functional analysis

Difficulties across context incl settings, life course, factors

What are aspects of clinical assessment for ADHD?

History taking

Family functioning

School history

Differential diagnosis and comorbidities

Risk assessment

Multi-informant

Psychometric rating scales

Cognitive assessment

Direct observational assessment

Consider normal developmental variation

Differential diagnoses for ADHD

ODD

SLD

Intellectual disability
ASD

Anxiety disorders

PTSD/abuse

Depression

Bipolar mania

Substance use disorders

Personality disorders

Medical conditions

Sleep disorders

Contextual/environmental/stress or adjustment related

What helps with differential diagnosis?

Looking beyond immediate symptom profile

Consider onset, persistence, pervasiveness, frequency, functional analysis of behaviour

Life course perspective

What leads to what?

Patterns