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What is ADHD?

You've likely heard about Attention-Deficit/Hyperactivity Disorder (ADHD, formerly known as "ADD") in the news or on the internet, but what EXACTLY is ADHD? Read on to learn more.

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An Introduction to ADHD

Attention-Deficit/Hyperactivity Disorder (ADHD; formerly known as ADD) has been gaining a lot of attention (no pun intended) in the past 10 years. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) defines ADHD as a persistent pattern of inattention and/or hyperactivity/impulsivity. A key component of this diagnosis is that it has to be severe enough to impair daily functioning.


So if you simply fidget or have trouble paying attention occasionally and it doesn’t have an impact on your grades or your ability to complete work without accommodations, you probably don’t have ADHD.

What are the 3 Presentations of ADHD?

The DSM-5 recognizes 3 presentations of ADHD (they used to be called the three “Types” or “Subtypes” of ADHD so you may be more familiar with that terminology):

  • Inattentive Presentation

  • Hyperactive or Impulsive Presentation

  • Combined Presentation


The names of these presentations are pretty reflective of what you would guess their related symptoms to be; Inattentive ADHD involves difficulty sustaining attention and difficulty organizing tasks, Hyperactive or Impulsive ADHD includes frequent fidgeting or constant feelings of restlessness and difficulty waiting your turn, and Combined ADHD combines symptoms from both Inattentive and Hyperactive/Impulsive.


For a more detailed explanation, please see my blog article here (Three Presentations of ADHD).

ADHD Diagnostic Criteria

In addition to having a certain number of symptoms of ADHD, there is a diagnostic requirement that the symptoms were present before the age of 12. This is why it is so important to do a thorough medical and psychological history when an adult is wondering if he/she/they have ADHD.


I mentioned above that the symptoms of ADHD have to be severe enough to have an impact on daily functioning — on top of this, the symptoms must occur in two or more settings.

How Common is ADHD?

The DSM-5 reports that ADHD occurs in about 5% of children and 2.5% of adults. There is a significant amount of research to support that it is cross-cultural, meaning it occurs globally. An article was published a while back suggesting that this was not the case, and one of my favorite ADHD speakers David Nowell wrote this fantastic article called “Of Course French Kids Have ADHD” supporting the idea that epidemiological evidence supports that ADHD is not merely a North American phenomenon.


Research also supports the theory that ADHD is more frequent in males than females, with a ratio of 2:1 in children and 1.6:1 in adults (with females being more likely to present with Inattentive features — to learn more about this, see my article here).

What Other Disorders are Comorbid With ADHD?

There are a variety of presentations of disorders that co-occur (or are “comorbid”) with ADHD, and some are more likely to co-occur in adults, whereas some are more likely to co-occur in children. Mood disorders like anxiety and depression are commonly diagnosed along with ADHD. Sometimes it can be difficult to identify which came first — depression/anxiety or ADHD. Learning disorders like dyslexia, dysgraphia, or dyscalculia are often comorbid with ADHD, as is Autism Spectrum Disorder (ASD). In addition, substance use disorders, Oppositional Defiant Disorder (ODD), and Conduct Disorder are frequently diagnosed alongside ADHD.


There is also evidence to suggest that a high percentage of people with eating disorders also have ADHD. One study conducted by Harvard Medical School found that girls with ADHD were almost four times more likely to have an eating disorder than those without ADHD.

If you’d like to learn more about ADHD or if you think you or a loved one might have ADHD, feel free to click the link below to contact me and set up a free consultation.
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