Understanding ADHD: Symptoms, Prevalence, and Diagnosis

• In the past 20 years, referrals have significantly increased, with most CAMHS assessments being for ADHD/Autism.

ADHD Defined

• ADHD is a neurodevelopmental disorder characterized by attention-deficit (inattention), hyperactivity, and impulsiveness.
• Diagnostically, it is referred to as 'attention-deficit/hyperactivity disorder' in the DSM and 'hyperkinetic disorder' in the ICD.

Prevalence

• In the UK, ADHD affects 3% of the population and 5% worldwide.
• It is more prevalent in boys than girls and typically begins in childhood, often persisting into adulthood.

Complex Presentation

• Core symptoms include hyperactivity, impulsiveness, and inattention.
• Individuals may also experience neurodevelopmental problems like difficulties in social communication, language, and motor skills.
• Emotional aspects include lability, irritability, and anxiety, which can lead to later depression.
• Behavioral issues can manifest as aggression, being headstrong/hurtful, and can be linked to later antisocial behavior.
• The presentation varies among individuals, with differences in symptom patterns and age of onset.

Comorbidity

• ADHD exhibits high comorbidity rates, between 50-66%.
• ASD comorbidity rate of 30%.
• Learning disability comorbidity rate of approximately 7-10%.
• Co-occurs with psychiatric and behavioral disorders such as conduct problems/antisocial behavior (40%) and mood disorders (5-20%).

Diagnosis

• Largely genetic, but not entirely.
• Diagnosis is based on a careful clinical history, including information from home, school, and clinical observation, as there is no specific genetic test, blood test, or brain scan.
• Symptoms must be present for over 6 months and cause significant problems.
• Diagnosis may include identifying one or both symptom patterns.
• To meet the criteria for ADHD, 5-6 symptoms from each category must be present.

Inattentive Symptoms

• Failure to give close attention to details/careless mistakes.
• Difficulty sustaining attention.
• Not listening when spoken to directly.
• Not following through on instructions/failure to finish tasks.
• Trouble organizing.
• Avoidance of tasks requiring sustained mental effort.
• Losing things.
• Being easily distracted.
• Forgetfulness.

Hyperactivity/Impulsivity Symptoms

• Fidgeting/squirming.
• Leaving seat when inappropriate.
• Running/climbing inappropriately.
• Difficulty engaging in leisure activities quietly.
• Always "on the go."
• Talking excessively.
• Blurting out answers.
• Difficulty waiting their turn.
• Interrupting/intruding on others.

Treatment (NICE Guidelines)

• A stepwise approach is recommended.
• Education and support for the family/school, including support groups.
• Classroom management strategies, parental psychoeducation, and behavioral management techniques.
• If symptoms persist, medication may be offered in conjunction with the above, but only for severe ADHD.
  • First-line medication: methylphenidate.

Categorical vs. Dimensional

• ADHD acts as a dimensional construct.
• The threshold for diagnosis is arbitrary and depends on the definition used.
• Subthreshold ADHD can still cause impairment and increase the risk of adverse outcomes.
  • Dimensional = continuously distributed risk dimension.
  • Categorical = clinical decisions are categorical.

Evidence

• Twin studies suggest the etiology of ADHD is consistent across the spectrum.
• Genetic studies suggest that risk factors are the same for the general population and those with ADHD.
• Full ADHD affects academic achievement, quality of life, and family/peer relationships.

Assumptions

• ADHD is not a new condition; it was described as early as 1798 by Alexander Crichton.
• Time trend studies show no evidence of increasing ADHD symptoms, but there is more awareness and recognition of ADHD.
• Economic costs extend beyond healthcare to education, social, and youth justice services. In the UK, the annual cost of treatment is £670 million.

Lecture Outline

• Definition, symptoms, epidemiology, risk factors, comorbidities, diagnosis, and treatment.

What is ADHD?

• A familial (highly heritable) neurodevelopmental condition.
• It is characterized by clinical and psychosocial impairments that often persist throughout life.
• Treatment is required when symptoms cause impairment.

Genetics

• Twin studies show ADHD is highly heritable (75%).
• Many genes show significant association such as DRD4, DRD5, 5-HTT, SNAP-25, DAT, DBH, HTR1B.

Brain Regions

• The most important brain regions for ADHD are the prefrontal cortex and cingulate gyrus.
• Neural dysfunction/abnormalities observed in multiple brain regions in ADHD are, temporal and parietal cortex , cerebellum, basal ganglia, prefrontal cortex and cingulate gyrus though none are specific to the condition.
• Includes Noradrenergic, Dopaminergic (greatest body of evidence), and Serotoninergic dysfunction.

Prefrontal Cortex

• Cortical maturation in the brain is delayed in children with ADHD.
• Differences are most pronounced in the prefrontal cortex.

Hyperactivity Symptoms

• Constant motion, being "on the go."
• Difficulty sitting still.
• Talking excessively/noisily.
• Fidgeting/breaking pencils.

Impulsivity Symptoms

• Difficulty inhibiting responses/reactions.
• Reacting without thinking of consequences.
• Not learning from consequences.
• Difficulty waiting their turn.

Inattention Symptoms

• Difficulty carrying out activities.
• Getting bored easily.
• Requiring extra effort for motivation.
• Refusing to do homework.
• Forgetting what they were doing.

Symptoms and Diagnosis

• Inattentive: Short attention span, missing details, avoiding work, easily distracted, forgetful, losing things, unable to listen, unable to carry out instructions, disorganized.
• Hyperactive: Unable to sit still, often running or climbing, "on the go," fidgets/taps hands/squirms in seat, excessive talking, unable to play quietly.
• Impulsive: Unable to wait for turn, interrupting conversations, blurting answers.

Diagnostic Criteria

• Symptoms must be present before the age of 12.
• Symptoms must be present in two or more settings (home, school/work, etc.).
• Symptoms must interfere/reduce quality of life.
• Six inattention and six hyperactive symptoms = combined presentation.

Epidemiology

• 5% of children and adolescents affected worldwide.
• 1% have a severe form (hyperkinetic with conduct problems).
• Symptoms persist into adulthood for 60%.

Heterogeneous Nature

• Various subtypes/forms and possible etiologies.
• Neurological mechanisms involve the PFC and anterior cingulate.
• Genetics play a role (dopamine and NE system).
• Environmental factors (pre/perinatal) like low weight at birth (2-3x), premature birth, maternal depression/smoking, paternal antisocial behavior, toxin exposure (mercury), TBI, or family instability.

Gender Gap

• There may be a gender-based referral bias.
• Diagnosed 3x more in boys than girls.
• Hyperactivity symptoms more pronounced in males.
• Males exhibit more externalizing symptoms like aggression, defiance and conduct problems, potentially leading to overdiagnosis.
• Females are less aggressive and exhibit more internalizing symptoms, such as depression/anxiety, increased rates of self-injury and suicide.

Comorbidities

• 2/3 present with other conditions.
• Conditions such as bipolar disorder, borderline personality disorder, depression, anxiety (most common), autism and general learning disability.

Tools for Diagnosis

• Pre-interview parental questionnaires.
• School observations.
• Medical examination (rule out other causes).
• QbTest (sometimes not accurate).
• Child and parent interviews (ADI-3).
• Behavior rating scales and teaching questionnaires.

Important Notes

• Diagnosis has become more difficult.
• Increased referrals, assessments are not always thorough, and more adults and women are being diagnosed.

Patient Pathway (NICE)

• Referral from primary care/schools for a child or adolescent with ADHD symptoms.
• Moderate/severe impairment: medication, maintenance, and management.
• Mild impairment: psychoeducation, non-pharmacological treatment, and watchful waiting.

Treatment Efficacy

• Medication is most effective for patients with ADHD only.
• Moderate to severe cases: medication is first-line, with 80% responding to stimulant medication.
• Treatment should be tailored to the patient's needs.

General Treatment

• An ADHD diagnosis does not always mean medication is needed.
• Patients may have found ways to compensate, and lifestyle/family changes can lead to improvements.
• Physical exercise is beneficial for depression, anxiety, and ADD.
• Treatment is not just about ADHD but also addressing associated problems.

Successful Treatment

• Individualized, multimodal (psychoeducation, psychosocial interventions, pharmacotherapy), regularly reviewed, involves joint decision-making, and is effective.

Pharmacotherapy Options

• Stimulants: Methylphenidate, Dexamphetamine, Lisdexamfetamine.
• Non-stimulants: Atomoxetine, Guanfacine.
• Unlicensed medication.
• Improvements seen after 4 weeks.
  • Ibuprofen = 0.7
  • Methylphenidate = 0.9
  • Lisdexamfetamine = 1.2
  • Atomoxetine = 0.7

Misconceptions

• Fears of side effects, lack of belief that medication is needed, expecting a miracle cure or instant effect, expecting 100% symptom correction, confusing ADHD symptoms with comorbidities, and expecting ADHD medication to address unrelated problems.

Mechanisms of Action

• Methylphenidate increases dopamine (DA) and norepinephrine (NE) by blocking reuptake through DAT and NET.
• Dexamfetamine blocks NET and DAT, increasing DA production.
• Atomoxetine is a norepinephrine reuptake blocker, increasing NE and DA levels in the PFC.

Methylphenidate Side Effects

• More common: Decreased appetite/anorexia, increased blood pressure/pulse, sleep disturbances, headaches/dizziness, stomach aches/nausea/dry mouth, arrhythmia/tachycardia, anxiety, irritability, depression.
• Less common: Psychotic symptoms, tearfulness, sedation, tics/worsening tics, chest pain, increased hepatic enzymes, constipation.

Dexamfetamine Side Effects

• More common: Increased blood pressure, insomnia, nausea, tachycardia, euphoria, restlessness, overstimulation, tic exacerbations, depression/anxiety/irritability.
• Less common: Headache, increased sweating, stomach cramps, psychosis, chest pain.

Atomoxetine Side Effects

• More common: Decreased appetite/anorexia, increased blood pressure/pulse, headache, nausea/vomiting/abdominal pain, constipation, fatigue/insomnia, dizziness, mood swings/irritability, sexual dysfunction, tachycardia.
• Less common: Suicidal thoughts, aggression, migraine, hepatoxicity.

Non-Pharmacological Interventions

• Nutrition: Diet trials, artificial food color exclusion, fatty acid supplements.
• Psychological: Cognitive training, neurofeedback, behavioral interventions.
• Psychological interventions had no significant impact.
• Nutrition had a small effect.