What’s the difference between ADD and ADHD?

Around one in 20 people has attention-deficit hyperactivity disorder (ADHD). It’s one of the most common neurodevelopmental disorders in childhood and often continues into adulthood.

ADHD is diagnosed when people experience problems with inattention and/or hyperactivity and impulsivity that negatively impacts them at school or work, in social settings and at home.

Some people call the condition attention-deficit disorder, or ADD. So what’s the difference?

In short, what was previously called ADD is now known as ADHD. So how did we get here?

Read more: ADHD affects girls too, and it can present differently to the way it does in boys. Here's what to look out for

Let’s start with some history

The first clinical description of children with inattention, hyperactivity and impulsivity was in 1902. British paediatrician Professor George Still presented a series of lectures about his observations of 43 children who were defiant, aggressive, undisciplined and extremely emotional or passionate.

Since then, our understanding of the condition evolved and made its way into the Diagnostic and Statistical Manual of Mental Disorders, known as the DSM. Clinicians use the DSM to diagnose mental health and neurodevelopmental conditions.

The first DSM, published in 1952, did not include a specific related child or adolescent category. But the second edition, published in 1968, included a section on behaviour disorders in young people. It referred to ADHD-type characteristics as “hyperkinetic reaction of childhood or adolescence”. This described the excessive, involuntary movement of children with the disorder.

In the early 1980s, the third DSM added a condition it called “attention deficit disorder”, listing two types: attention deficit disorder with hyperactivity (ADDH) and attention deficit disorder as the subtype without the hyperactivity.

However, seven years later, a revised DSM (DSM-III-R) replaced ADD (and its two sub-types) with ADHD and three sub-types we have today:

• predominantly inattentive
• predominantly hyperactive-impulsive
• combined.

Read more: I think I have ADHD, how do I get a diagnosis? What might it mean for me?

Why change ADD to ADHD?

ADHD replaced ADD in the DSM-III-R in 1987 for a number of reasons.

First was the controversy and debate over the presence or absence of hyperactivity: the “H” in ADHD. When ADD was initially named, little research had been done to determine the similarities and differences between the two sub-types.

The next issue was around the term “attention-deficit” and whether these deficits were similar or different across both sub-types. Questions also arose about the extent of these differences: if these sub-types were so different, were they actually different conditions?

Meanwhile, a new focus on inattention (an “attention deficit”) recognised that children with inattentive behaviours may not necessarily be disruptive and challenging but are more likely to be forgetful and daydreamers.

Why do some people use the term ADD?

There was a surge of diagnoses in the 1980s. So it’s understandable that some people still hold onto the term ADD.

Some may identify as having ADD because out of habit, because this is what they were originally diagnosed with or because they don’t have hyperactivity/impulsivity traits.

Others who don’t have ADHD may use the term they came across in the 80s or 90s, not knowing the terminology has changed.

How is ADHD currently diagnosed?

The three sub-types of ADHD, outlined in the DSM-5 are:

• predominantly inattentive. People with the inattentive sub-type have difficulty sustaining concentration, are easily distracted and forgetful, lose things frequently, and are unable to follow detailed instructions

• predominantly hyperactive-impulsive. Those with this sub-type find it hard to be still, need to move constantly in structured situations, frequently interrupt others, talk non-stop and struggle with self control

• combined. Those with the combined sub-type experience the characteristics of those who are inattentive and hyperactive-impulsive.

ADHD diagnoses continue to rise among children and adults. And while ADHD was commonly diagnosed in boys, more recently we have seen growing numbers of girls and women seeking diagnoses.

However, some international experts contest the expanded definition of ADHD, driven by clinical practice in the United States. They argue the challenges of unwanted behaviours and educational outcomes for young people with the condition are uniquely shaped by each country’s cultural, political and local factors.

Regardless of the name change to reflect what we know about the condition, ADHD continues to impact educational, social and life situations of many children, adolescents and adults.

Read more: What’s the difference between autism and Asperger’s disorder?