Early Signs of ADHD: Why Can’t My Child Sit Still?

If you’ve spent months watching your child bounce off the walls, struggle to concentrate, or struggle with small changes, you’ve probably asked yourself whether something more is going on. The early signs of ADHD are often the first clue that a child’s brain is wired differently, and recognising them early can make a significant difference to the support your child receives.

ADHD (Attention Deficit Hyperactivity Disorder) is a neurodevelopmental condition, meaning it affects how the brain develops and functions. It is not caused by poor parenting, diet, or a lack of discipline. According to the NHS, symptoms usually start before the age of 12 and involve a child’s ability to pay attention, their energy levels, and their ability to control their impulses.

In children with ADHD, the brain’s prefrontal cortex, the part responsible for impulse control, attention, and planning, develops more slowly than in other children. Research has shown that the cortex in children with ADHD matures around three years later than average.

A ten-year-old with ADHD may have frontal lobe development closer to that of a seven-year-old. Expecting them to sit still as long as their peers is a mismatch between the child and the environment. Movement is also the brain’s way of self-regulating. When a child fidgets or paces, they are often helping their brain generate the stimulation it needs to focus. It is not deliberate disruption.

Signs of ADHD in children are usually apparent by the age of six and will be evident in more than one environment, such as both at home and at school. A child who only struggles in one setting may be responding to a specific environment rather than showing early signs of ADHD.

The early signs fall into two categories, as defined by the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, the global standard used by clinicians to diagnose mental health conditions) and the ICD-11 (the equivalent framework from the World Health Organization), both used in the UK.

No single behaviour confirms ADHD. The key question is whether these signs are persistent, present across more than one setting, and causing real difficulty in daily life.

Most young children are energetic, impulsive, and easily distracted at times. The difference with ADHD is persistence and impact.

According to Great Ormond Street Hospital, symptoms must be present before age 12, across two or more settings, and there must be clear evidence that they interfere with the child’s daily functioning.

ADHD often presents alongside other conditions. Approximately 60-80% of children with ADHD will have at least one co-occurring condition, such as a social communication disorder, dyslexia, or dyspraxia. Anxiety, sleep difficulties, and autism can all overlap in presentation too, which is why a thorough assessment matters.

Early signs of ADHD can also look different depending on your child’s age and sex. Girls are more likely to show inattentive symptoms rather than hyperactivity, meaning they are often missed. Our article on why ADHD symptoms in girls are so easy to miss covers this in detail, and our article on what ADHD symptoms in boys look like explores the more visible presentations.

Diagnosis follows guidelines set by NICE (the National Institute for Health and Care Excellence), the independent body that sets clinical standards for healthcare in England and Wales. It must be carried out by a qualified specialist, typically a paediatrician (a doctor specialising in children’s health) or a child and adolescent psychiatrist (a doctor trained in children’s mental health conditions).

There is no blood test or scan that confirms ADHD. The assessment draws on information from you, your child’s school, and direct clinical observation. The NHS route starts with your GP (General Practitioner, your family doctor), who refers to CAMHS (Child and Adolescent Mental Health Services), the NHS service responsible for children’s mental health assessments. Our guide to ADHD in children covers each step in detail.

NHS waiting times are significant, with many children waiting well over a year. KPI:Access is a healthcare connector service that links families with qualified specialists who carry out ADHD assessments for children in London and Croydon. No GP referral is needed, and appointments can often be arranged within days. Specialists work to NICE and Royal College of Psychiatrists standards.

KPI:Access is part of KPI:Health, a wider healthcare group that has connected over 300,000 people with assessments across the UK, with 99.2% rating their experience as good or very good.

If you are concerned about your child and want to explore next steps, our team is here to help. Learn more about ADHD assessments for children through KPI:Access.