Year 2020
May 2020
20 May 2020

A Specialist's Point Of View: ADHD - Definition and prevalence

ADHD – Definition and prevalence

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopment disorder that is regarded as the most common behavioural condition in children and the second most common chronic illness in children.

The Centres for Disease Control and Prevention (CDC) estimates that 9.4 % of US children have ever been diagnosed with ADHD. In Singapore, based on the Ministry of Health ADHD guidelines published in 2014, the local prevalence is estimated at less than 5%. However, this could be due to under detection.

More males than females are diagnosed with ADHD (CDC figures 13.0% vs 4.2 %). As girls commonly present with inattention and fidgetiness as opposed to hyperactivity / impulsivity, their difficulties are not so obvious and are harder to detect.

ADHD is currently subcategorised as ADHD – Hyperactive/ Impulsive subtype, ADHD- Inattentive subtype or ADHD – Combined subtype. Children may present with a combination of hyperactivity, impulsivity, inattention and poor focus and/ or disruptive behaviour. Some students are not overly active but do still have significant features of inattention. These students are harder to detect as they are not disruptive; instead they are more easily distractible and ‘dreamy’. This is especially so in girls.


Diagnosis of ADHD are usually carried out by doctors – generally psychiatrists, paediatricians- and by psychologists.

Coexisting conditions do need to be identified as many children with ADHD also have learning and developmental difficulties, emotional conditions (commonly anxiety), executive functioning deficits and social skills issues. Executive functioning issues include difficulties with organisation, poor emotional regulation and poor planning abilities. Many of these children also have difficulties with sleep.

Comprehensive management of ADHD requires both management of attention / activity levels as well as any identified learning, emotional, executive functioning or social issues.

ADHD can be diagnosed as young as 4 years of age but most clinicians will try to delay a formal diagnosis till at least 7 years of age. Nevertheless, symptoms of ADHD can be present from toddlerhood.


Behavioural management is recommended as first line management for preschoolers, mainly in the form of parent training programmes, for example the ‘Triple P’ programme. Parent and teacher training also helps with day to day management of older students. Psychologists provide sessions for behavioural management with the child and often have sessions with parents as well to give guidance on consistent parenting boundaries and parenting responses. Consistent responses from adults is vital for children with ADHD  to help them manage their behaviour. Many of these children often appear not to learn from their mistakes and this is a recognised pattern due to their unique neurology. Hence parenting boundaries need to be consistently reinforced.

Children with ADHD tend to be more dysregulated if they are sleep deprived. Unfortunately, sleep deprivation is common in the local paediatric population. Recommended sleep durations vary by age. Children aged 3-5 years need 10-13 hours of sleep; children aged 6-12 years need 9-12 hours and teenagers need 8-10 hours of sleep.

Ensure a healthy balanced diet, making sure that the child does eat breakfast. Poor nutrition aggravates inattention. Regular physical exercise will help  to burn off excess energy and some students do focus better after they have had a session of physical activity.

Parental fatigue, stress and disagreements because of the child’s behaviour are not uncommon. This is especially so for the main caregiver, usually the mothers. Care for the child does extend to care for the family.

Medication for management of ADHD is effective. In Singapore, we have access to methylphenidate and  atomoxetine. Methylphenidate is usually the first line drug used. The response rate is higher for methylphenidate compared to atomoxetine.

There are differences in terms of patient response to the drug and the duration of action of the drug. Common side effects reported include loss of appetite when the medication is active. This does not affect all children taking the drug.

Medication can be stopped if the child no  longer requires it and has developed sufficient skills to manage their own behaviour. Usually this also means that parents have also used more targetted parenting techniques to help their child manage.

Supplements in the form of fish oils have not been shown in meta-analysis to provide statistically significant effects on behaviours. Parents do however often wish to try it out as it is not ‘medicine’.

There are numerous supplements and diets which claim to ‘cure’ ADHD. There is no robust evidence from meta-analysis to suggest that these supplements or diets help ADHD.

Local support groups include SPARK (, which is a parent headed non-profit organisation.

Long term outcomes

ADHD features may persist into adulthood. However, even with fewer ADHD symptoms, they are still at risk for other psychiatric disorders, with poorer outcomes.  Due to inconsistent diagnostic criteria, variable reporting and loss of patients to follow up, the reported rates of ADHD persistence into adulthood range from 4% to 78%.

The hyperactivity symptoms reduce over the teenage years while the inattentive symptoms do tend to persist.

Studies suggest that students with ADHD underperform academically compared to non-ADHD controls. This is made more severe if there is an accompanying learning disorder. Social functioning is often compromised in children with ADHD and there is often low self – esteem. There is a higher risk of criminal activity.

Dr Tammi Quek Chaey Moon

MBBS (London), MRCPcH, M.Med (Paediatrics), FAMS

Quek and Marcou Developmental and Behavioural Paediatrics Clinic Pte Ltd

10 Sinaran Drive #10-12 Novena Medical Center

Singapore 307506

Tel: 65-6397-6637

Fax: 65-6397-7085

Email: [email protected]

Dr Quek received her undergraduate medical training at University College London (University of London) and graduated in 1999, with awards in genetics, physiology, pathology, pharmacology and overall performance. Returning to Singapore in 2000, she entered the post-graduate training programme in Paediatrics at the National University Hospital, Singapore and passed the Singapore and British examinations in Pediatrics in 2003. After fully completing the six year training program, she became fully registered as a paediatrician with the Singapore Medical Council in 2007 and also became a Fellow of the Academy of Medicine, Singapore in 2008. She is a member of the Royal College of Paediatrics and Child Health (United Kingdom).

She joined the Child Development Unit at the National University Hospital in 2008 and worked with children with a wide variety of developmental and behavioural concerns, including Autism Spectrum Disorder, Attention Deficit Hyperactivity Disorder, learning differences/ disorders, developmental delays, hearing impairments, child development in the context of chronic diseases or after recovery from childhood cancers etc. She also liaised and worked closely with the ENT department at NUH, working to help children with hearing impairments to optimise their learning and development.

Dr Quek has been working in private practice since 2014. She is currently the director of Quek and Marcou Developmental and Behavioural Paediatrics Clinic.

She works with a wide range of children and families, both resident in Singapore and internationally. She works closely with local and international schools to optimize support for the children.

Her work involves not only the child but also helping and working collaboratively with parents and families to understand their child’s strengths and vulnerabilities and supporting parents in advocating for their child.


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