While there is still much to be understood about the development of Attention-Deficit/Hyperactivity Disorder (ADHD), the current state of scientific research largely suggests it reflects a neurobiological condition (a condition affecting the brain) with a strong genetic component. Everyone displays inattention and/or hyperactivity from time to time, and yet not everyone has ADHD. It can be difficult to determine when differences are at a level that is typical of everyone’s experience and when they go beyond that to a degree that warrants diagnosis. To do so, an in-depth assessment must be conducted by combining information over time and from multiple sources, including the individual and, if possible, others who know them well.

It is important to note that these are three main presentations of ADHD.

1. ADHD, inattentive presentation (formerly referred to as ADD). This presentation of ADHD is characterized predominantly by inattention and distractibility, without hyperactivity. Differences may include:

• Failing to give close attention to details or making careless mistakes

• Having difficulty sustaining attention

• Not appearing to listen when being spoken to

• Struggling to follow instructions

• Having difficulty with organization

• Avoiding or disliking tasks that require sustained mental effort

• Losing things frequently

• Being easily distracted

• Being forgetful in daily activities

2. ADHD, impulsive/hyperactive presentation. This, the least common presentation of ADHD, is characterized by impulsive and hyperactive behaviours without inattention and distractibility. Differences may include:

• Frequently fidgeting with hands or feet or squirming in chair

• Having difficulty remaining seated

• Running about or climbing excessively; extreme restlessness in adults

• Difficulty engaging in activities quietly

• Acting as if driven by a motor; adults will often feel restless, but may not demonstrate this outwardly

• Talking excessively

• Blurting out answers

• Difficulty waiting or taking turns

• Interrupting or intruding upon others

3. ADHD, combined presentation. This is the most common presentation of ADHD and is characterized by clinically significant differences with inattention and impulsivity/hyperactivity (as described above).

How information is collected varies depending on the client’s age and presentation. Often ADHD assessments include:

• A developmental history form completed by the parents or the adult client prior to the assessment

• In-depth interviews with the client and their parents or another person who knows them well (such as a spouse, roommate, or close friend)

• Semi-structured interview forms and/or questionnaires completed by the classroom teachers, the client, and/or the client’s parents

• Review of background academic records (e.g., report cards, Individualized Education Plans) and any previous assessment reports (e.g., psycho-educational assessments)

• Direct assessment of the client’s attention

• Screening for any social, emotional and/or behavioural difficulties that could be related to attention or hyperactivity/impulsivity

Following the assessment, the psychologist reviews all of the collected information and evaluates the individual’s difficulties with attention, hyperactivity, and impulsivity, as well as other contributing factors. This information is then shared during a feedback appointment. A written report is sent out several weeks after the feedback session.