Children with ADHD often have mental health comorbidities that can increase their challenges, explains Dr Pradeep Rao.


Attention deficit hyperactivity disorder is a common neurodevelopmental disorder affecting about 5% of children, characterised by hyperactivity, inattention and impulsivity with emotional and behavioural dysregulation common.

Dr Pradeep Rao

ADHD has a high burden of disease and can impact school and family life, friendships and social relationships. It is also a highly comorbid disorder, so a comprehensive assessment must always include an assessment for comorbidities, as 30-50% of children with ADHD suffer from them. Early diagnosis and treatment of comorbidities results in better long-term prognosis.

Mental health disorders commonly comorbid with ADHD include anxiety, mood and behavioural disorders, and other neurodevelopmental disorders.

Anxiety disorders occur in about 25-50% of children with ADHD and can be highly debilitating and increase the burden of the condition. These children commonly have academic and social difficulties and need support in the school environment. Generalised anxiety disorder, social anxiety disorder and separation anxiety disorder are commonly seen comorbidities. 

Mood disorders such as depressive disorders are also relatively common. These can be a result of the social isolation, while academic difficulties may result in social difficulties and bullying at school, causing low self-esteem and, in some instances, a full-fledged mood disorder.

There is increasing evidence that children with ADHD have a higher rate of suicidal thoughts and self-harm and attempted suicide compared to the general population. Presentation to an emergency department with low mood and self-harm/suicidal ideation may be the first presentation of ADHD. 

Behavioural disorders such as oppositional defiant disorder and conduct disorder also commonly occur in children and adolescents with ADHD. In a school setting, they usually precipitate further social isolation and bullying and are also associated with disengagement. The presence of severe behavioural disorders comorbid with ADHD has been linked to increased offending behaviours and incarceration. The prevalence of ADHD in adult male prisoners is about 25%. 

Neurodevelopmental disorders such as autism spectrum disorder are also commonly comorbid with ADHD, although to a lesser extent than anxiety and behavioural disorders. Comorbidity of neurodevelopmental disorders can result in increased behavioural problems and can have significant impact on academic options.

Children with ADHD often have difficulties with sleep. This could be a result of disorganisation leading to poor sleep hygiene, excessive use of technology/screens around bedtime, the effect of some of medications used in the treatment of ADHD or a disturbance of the circadian rhythm. 

Learning disorders such as dyslexia and dysgraphia, motor coordination difficulties, tic disorder and Tourette’s syndrome and substance abuse are other comorbidities of note.

Comorbidity in ADHD complicates what is already a high burden of disease and impacts on all domains of the child and family’s life. There is a high carer burden on parents.

Although the economic cost of ADHD itself is unknown, the annual costs to society of ADHD and comorbidities has been estimated to be over a $100 billion in the US.

Screening questions for all comorbidities followed by detailed assessments including use of standardised questionnaires (for e.g. RCADS – Revised Children’s Anxiety and Depression Scale) are highly recommended.

An assessment of comorbidities is multidisciplinary and includes, where clinically indicated, a neuropsychological assessment, speech and language assessment and an occupational therapy assessment, as well as assessment by a paediatrician/psychiatrist. Where a comorbid mental health condition is the predominant presenting feature, an assessment by a child and adolescent psychiatrist in addition to a paediatric assessment is recommended. 

Optimal treatment of ADHD may provide a beneficial impact on comorbidities such as behavioural disorders and anxiety. Occasionally, some medications used for the treatment of ADHD may worsen some comorbid conditions and may require careful dose titration or may need changing to alternate formulations.

The Complex Attention and Hyperactivity Disorders Service (CAHDS) is part of the Child and Adolescent Health Service that works with children aged under 18 years and their families. Children and young people accessing CAHDS must have a diagnosis of ADHD and currently being treated by a paediatrician, child psychiatrist or neurologist. Clinicians work with children, young people and their families who have not responded to typical ADHD interventions, and are continuing to experience persistent problems with symptoms or functioning. 

CAHDS provides a comprehensive assessment for comorbidities in complex presentations but does not offer ongoing individual treatment or pharmacological intervention. It does recommend other services to work in partnership with the referrer. CAHDS also provides targeted group treatment programs to children and families accessing the service. 

ED: Dr Pradeep Rao is Clinical Associate Professor and Head of Service at CAHDS.