How is ADHD diagnosed?

The diagnosis of ADHD is based on details obtained from careful listening by the doctor to the patient's history. Often, it can take up to a whole hour for a family to tell their story in their own words, with minimum prompting by the doctor.

Questionnaires are sometimes used to help make sure all of the key areas are covered but some doctors do not use them because they can in fact give bias towards details that are not necessarily part of the patient history. Some questionnaires are available on the internet or in books such as 'Driven to Distraction' by Hallowell and Ratey. The most popular are from overseas experts such as CK Connors and TM Achenbach.

Corroboration of the story from parents, siblings, spouses and teachers is often sought. School reports over a number of years are a great help because, even in today's environment of politically correct reports (where no child is acknowledged as having a problem), comments about concentration, distraction and having trouble completing work, crop up year by year.

It is important to allow for a full assessment by a doctor before arriving at a firm 'yes' or 'no' conclusion to the question of ADHD. And it is important to keep an open mind until this assessment is complete, as it can be much harder to assess the person accurately if someone, or their family, has already made their mind up.

Simple tests of concentration and of intelligence are used during the doctor's assessment, and sometimes a visit to an educational psychologist will help to obtain a more accurate measure of ability and specific learning difficulties.

Another test, sometimes used, is the computer-based Test Of Variable Attention (TOVA), which can measure concentration and impulsivity either visually or auditorally. The test is both specific and sensitive for ADHD; however, no test is more important than the careful detailing of the person's history.

While ADHD can often be a relatively straightforward diagnosis for a doctor to make, there are other possibilities to consider, some of which may co-exist with ADHD or else be separate issues. At least half the children with ADHD also have oppositional defiant disorder (always taking the opposite point of view), conduct disorder (antisocial behaviour with no apparent conscience) or a specific learning disorder.

Other conditions can be confused with or be present in addition to ADHD:

• Asperger syndrome describes children who seem emotionally cut off from others while sharing many of the other features of ADHD.
• Depression is common because of the frustration caused by ADHD.
• Anxiety may accompany ADHD because past experience has shown that impulsive decisions frequently go wrong.
• Obsessive-compulsive disorder occurs particularly in those with ADHD who are perfectionists, frustrated by their unreachable standards in the face of poor concentration.
• Tourette syndrome is a rare and progressive neurological condition that starts off like ADHD.
• Petit mal epilepsy can mimic the inattention of ADHD.
• Intellectual handicap from birth or brain damage can appear as poor attention, but these people are achieving according to their limited ability.
• In adults, schizophrenia and bipolar disorder can occur on top of pre-existing ADHD.
• Hypothyroidism will cause slow responses in those affected, but this condition should be abundantly evident for other reasons.

See also: ADHD - what is it?

See also: ADHD - how is it treated?

Recommended further reading:

• Understanding ADHD by Dr Christopher Green
• The Hidden Handicap by Dr Gordon Serfontein
• You and Your ADD Child by Ian Wallace
• ADD in Adults by Dr Gordon Serfontein
• Driven to Distraction by Drs Hallowell and Ratey
• Answers to Distraction by Drs Hallowell and Ratey

All of these are available from good bookshops or the library.

This article was written by Dr Tony Hanne, an Auckland GP who specialises in ADHD. Originally published in Pharmacy Today newspaper. Copyright 2003 UBM Medica (NZ) Ltd.

Your own family doctor will be able to provide help with ADHD.