What is ADHD?

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neuro-developmental (brain-based) condition. It impacts the brain’s ability to plan, focus, and execute goals.

These types of activities are part of the brain’s Executive Functioning (EF) capabilities, collectively acting much like an “air traffic controller”, and relate to self-regulation.

Individuals with ADHD often have difficulties with:

  • impulse-control (regulating behaviour)
  • overwhelming feelings (regulating emotions)
  • difficulties with distraction or over-focusing (regulating attention)
  • difficulties with organization (regulating order and time)

Difficulties with EF skills can also present as:

  • reduced working memory where there is either not enough available or it is overloaded but both result in forgetting;
  • a lack of flexible thinking like understanding someone else’s perspective or easily adapting to unexpected situations;
  • challenges with time sensitivity, especially with future-oriented considerations like consequences, impacts and deadlines.

These difficulties must be beyond what would be expected for someone of the same age or developmental level; they are NOT related to intelligence, parenting, food additives or other environmental factors, though ADHD-like symptoms can be the result of brain injury and trauma as well.

ADHD is diagnosed in about 9% of children and about 5% of adults.  It has a high rate of heredity at about 75% meaning that ADHD tends to run in families.

Executive functions are tied to brain development and maturation, and do not fully develop until the early to mid-20s. However, individuals with ADHD typically lag behind in the development of these functions (anywhere from 1 to 3 years or more) and can appear immature compared to their peers. ADHD usually begins in childhood (before age 12) and can last across the lifespan.


Symptom Grouping

In the DSM-5, a medical classification system used for diagnosis, 3 types of ADHD are officially recognized:

1.   Predominantly Inattentive Presentation.  Inattention refers to wandering off task, seeming not to listen, being easily distracted, daydreaming, being disorganized, being forgetful, and losing materials. About 30% of individuals with ADHD only have difficulty with attention.

2.  Predominantly Hyperactive-Impulsive Presentation. Hyperactivity refers to over-activity, restlessness, fidgeting, talkativeness, and being unable to stay seated. Impulsivity refers to intruding in other people’s activities (e.g. interrupting, blurting out), being unable to wait, and making hasty decisions without thinking about the potential consequences. About 10% of individuals with ADHD only have difficulty with hyperactivity/impulsivity.

3.  Combined Presentation. The Combined Presentation is the most common, with 50-70% of individuals with ADHD having problems with both inattention and hyperactivity/impulsivity.


ADHD Symptom Variability

Because individuals are unique and so is the development of their brains, ADHD symptoms vary with each person.

  • Symptoms affect each person to varying degrees (mild, moderate, and severe).
  • Some symptoms can affect an individual more severely than others.
  • Symptoms may change from moment to moment and day to day.
  • Symptoms can depend on the setting or what the individual is doing.
  • Symptoms are often worse when the individual is bored, unsupervised, or doing something difficult.
  • Symptoms are often better when the individual is doing something they enjoy, when rewarded immediately, or when closely monitored.
  • Symptoms can change over time. For example, in adolescence/young adulthood, hyperactive symptoms are often less obvious than in childhood. However, difficulties with restlessness, inattention, poor planning, and impulsivity can last over the lifetime.
  • Many children with ADHD continue to struggle with symptoms into adulthood.



ADHD is the official medical term for the condition. Attention Deficit Disorder (ADD) is considered an outdated term for ADHD and was used in the past to describe the inattentive type of ADHD. The newest way of thinking about ADHD is to think about significant symptoms, not specific types.