What is ADHD?
A comprehensive, plain-English guide to understanding Attention Deficit Hyperactivity Disorder — written by our specialist clinical team and aligned with NICE guidelines NG87.
Understanding ADHD
What is ADHD?
Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental conditions in the UK, affecting children and adults across all backgrounds. It is a recognised medical condition — not a personality trait, parenting failure or lifestyle choice.
ADHD is characterised by a persistent pattern of inattention and/or hyperactivity-impulsivity that has a direct negative impact on academic, occupational or social functioning, at a level outside the limits of normal variation expected for age and intellectual functioning.
A brain-based condition
ADHD involves structural and functional differences in the brain — particularly in the prefrontal cortex, which governs attention, planning, impulse control and emotional regulation. These differences affect how the brain processes dopamine and norepinephrine.
A lifelong condition
ADHD doesn't disappear in adulthood. While symptoms can evolve and many people develop coping strategies, the underlying neurodevelopmental differences remain throughout life. With the right support, people with ADHD can and do thrive.
Highly heritable
ADHD is one of the most heritable conditions in medicine. If a parent has ADHD, their child has approximately a 50% chance of also having it. Diagnosis often runs in families.
Highly treatable
Approximately 70% of people with ADHD respond positively to appropriate treatment — medication, CBT, psychoeducation, coaching and workplace adjustments, often in combination.
Presentations of ADHD
The three types of ADHD
NICE guidelines recognise three distinct presentations, each with a different pattern of symptoms.
Predominantly Inattentive
Characterised by difficulty sustaining attention, tendency to be easily distracted, forgetfulness and difficulty organising tasks. Often less visible — this presentation is frequently missed, particularly in girls and women.
Predominantly Hyperactive-Impulsive
Characterised by restlessness, excessive talking, difficulty waiting, impulsive decision-making and interrupting others. More commonly identified in children — particularly boys.
Combined Presentation
The most common presentation — a combination of significant inattentive and hyperactive-impulsive symptoms. Most adults diagnosed with ADHD present with the combined type.
Signs & Symptoms
Recognising ADHD symptoms
Symptoms vary significantly between individuals and change across the lifespan. Here are the core symptom domains recognised by NICE guidelines.
Inattention symptoms
- ·Difficulty sustaining attention in tasks or play
- ·Frequent careless mistakes — missing details
- ·Does not seem to listen when spoken to directly
- ·Fails to follow through on instructions or tasks
- ·Difficulty organising tasks and activities
- ·Avoids tasks requiring sustained mental effort
- ·Loses things necessary for tasks
- ·Easily distracted by external stimuli
- ·Forgetful in daily activities
Hyperactivity & impulsivity
- ·Fidgets, taps hands or feet, squirms in seat
- ·Leaves seat when expected to remain seated
- ·Runs about or climbs in inappropriate situations
- ·Unable to play or engage in activities quietly
- ·Often "on the go" — as if driven by a motor
- ·Talks excessively
- ·Blurts out answers before questions are finished
- ·Difficulty waiting turn
- ·Interrupts or intrudes on others
Aetiology
What causes ADHD?
ADHD is a neurodevelopmental condition with strong genetic and neurobiological roots. Research is clear — ADHD is not caused by poor parenting, diet, screen time or lack of discipline.
Genetics (strongest factor)
ADHD is one of the most heritable conditions in medicine, with heritability estimates of 70–80%. Specific genes involved in dopamine and norepinephrine regulation have been implicated.
Neurobiological differences
Brain imaging studies show structural and functional differences in people with ADHD — particularly in the prefrontal cortex, basal ganglia and cerebellum. These affect attention regulation and executive function.
Environmental factors
Certain prenatal exposures (maternal smoking, alcohol, stress), premature birth and low birth weight are associated with increased ADHD risk. These are contributing factors — not causes in isolation.
ADHD Across the Lifespan
ADHD doesn't end at 18
Adult ADHD is significantly under-diagnosed. Many adults have lived their entire lives not knowing why they find certain things so difficult — and finally getting a diagnosis can be life-changing.
In adults, ADHD often presents differently to the classic childhood picture. Hyperactivity may be internal — a constant mental restlessness rather than physical movement. Inattention may manifest as difficulty staying in jobs, maintaining relationships, managing finances or meeting deadlines.
Many adults with undiagnosed ADHD have developed coping strategies that mask symptoms — making diagnosis harder, but not less important. Common co-occurring conditions include anxiety, depression and sleep disorders.
How adult ADHD commonly presents
- ·Chronic disorganisation and poor time management
- ·Difficulty prioritising tasks or starting them
- ·Impulsive decision-making — spending, relationships, career
- ·Emotional dysregulation — quick to anger or frustration
- ·Low frustration tolerance
- ·Difficulty maintaining focus in meetings or conversations
- ·Forgetfulness affecting work and relationships
- ·Sense of underachievement despite high intelligence
What often gets in the way of diagnosis
- ·Symptoms masked by coping strategies developed over decades
- ·Co-occurring conditions (anxiety, depression) treated instead
- ·Diagnosis perceived as "just for children"
- ·Inattentive presentation less visible than hyperactive type
- ·Women and girls particularly likely to be overlooked
- ·Long NHS waiting times making private assessment necessary
ADHD in Young People
Early identification changes outcomes
Children and teenagers with undiagnosed ADHD often face significant academic, social and emotional challenges. Early diagnosis and appropriate support can transform outcomes.
Signs in children & teens
- ·Difficulty following instructions or completing tasks
- ·Losing school equipment, forgetting homework
- ·Impulsive behaviour — hitting out, shouting
- ·Difficulty sitting still or being quiet when required
- ·Poor peer relationships due to impulsive behaviour
- ·Academic underperformance despite apparent ability
- ·Low self-esteem from repeated "failures"
- ·Emotional outbursts disproportionate to the situation
What assessment involves at NeuroAxis
- ·Initial parent/carer screening call
- ·Pre-assessment questionnaires for parent and teacher
- ·QbCheck objective ADHD test (included as standard)
- ·Full diagnostic assessment with child and parent/carer
- ·School and behavioural history review
- ·Detailed written clinical report
- ·School support guidance and recommendations
- ·Medication pathway referral if clinically appropriate
Setting the Record Straight
Common myths about ADHD — debunked
ADHD isn't a real condition
ADHD is one of the most researched and well-evidenced neurodevelopmental conditions in medicine. It is recognised by the WHO, NHS and NICE. The neurobiological differences are visible on brain imaging.
ADHD only affects children
Approximately 60–70% of children with ADHD continue to have clinically significant symptoms in adulthood. Many adults are only diagnosed later in life — often after a child's diagnosis reveals a family pattern.
People with ADHD just need more discipline
ADHD is a neurobiological condition, not a behavioural choice. The brain differences in ADHD are structural and functional — not the result of poor upbringing, weak character or laziness.
You can't have ADHD if you can focus on things you enjoy
The ability to hyperfocus on high-interest activities is actually a hallmark of ADHD — not evidence against it. ADHD affects the ability to regulate attention, not simply the capacity for it.
ADHD medication is dangerous or addictive
ADHD medications are among the most studied in medicine. When prescribed and monitored appropriately, they are safe and highly effective. Untreated ADHD carries significantly higher risks.
Girls don't get ADHD
Girls are significantly under-diagnosed because they more commonly present with the inattentive type — which is less disruptive and less visible than the hyperactive type. Many women are diagnosed only in adulthood.
Management Options
How is ADHD treated in the UK?
NICE guidelines recommend a multimodal approach — combining medication, psychological therapies and practical support strategies tailored to the individual.
Medication
ADHD medications work by increasing dopamine and norepinephrine availability in the brain, improving attention regulation and impulse control. Stimulant medications (methylphenidate, lisdexamfetamine) and non-stimulants (atomoxetine) are NICE-recommended first-line treatments.
Psychological Therapies
Cognitive Behavioural Therapy (CBT) adapted for ADHD, ADHD coaching, mindfulness-based approaches and psychoeducation all have evidence behind them. These help people develop strategies for executive function challenges.
Practical Support
Workplace adjustments, educational support plans (EHCPs for children), organisational strategies and lifestyle adaptations (sleep hygiene, exercise, nutrition) all play an important role in ADHD management.
Getting Diagnosed
Think ADHD might apply to you or your child?
Getting an assessment is the first step. Here's how NeuroAxis makes it straightforward.
✓No GP referral required
You can book directly with NeuroAxis — no need to visit your GP first or wait for a referral.
✓No waiting list
Appointments are typically available within days. You won't wait months or years for answers.
✓QbCheck included
Every assessment includes the QbCheck objective test — UKCA-marked and NICE-recommended. Included as standard.
Ready to get the clarity you deserve?
No waiting list · No GP referral · Appointments available this week