ADD vs. ADHD: what’s the difference?

Attention-deficit disorder, which we would call ADD if it were still a thing, is no longer a formal medical diagnosis. Instead, medical professionals now consider ADD—marked by inattentiveness—as one aspect of attention-deficit/hyperactivity disorder (ADHD).

ADHD is among the more common childhood mental disorders and can last into adulthood in many cases. A recent study estimated that sixty percent of children with ADHD experience symptoms into their mid-20's, and 41 percent had both symptoms and impairments as young adults (Sibley, 2017).

As formally diagnosed by a healthcare professional, ADHD typically involves an inability to focus. However, other ADHD symptoms include impulsivity and hyperactivity. 

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ADHD is broadly defined as “a behavioral condition that makes focusing on everyday requests and routines challenging” (APA, n.d.). It is a complex disorder that affects millions of children and is common in adults, too. 

ADHD plays out differently depending on two primary aspects, each of which comes with its own batch of symptoms (NIMH, 2021):

Primarily inattentive (what used to be called ADD)

• Can’t pay close attention to details or makes careless mistakes

• Struggles to stay focused on tasks or activities

• Does not seem to listen well

• Doesn’t follow through on instructions 

• Struggles to organize tasks, leading to missed deadlines

• Avoids or dislikes tasks that require sustained mental effort

• Often loses things needed for tasks or daily life

• Is easily distracted

• Forgets daily tasks, activities, or appointments

Primarily hyperactive-impulsive

• Fidgets, taps hands or feet, or squirms

• Can’t stay seated

• Is relentless or “always on the go”

• Can’t engage in leisure activities quietly

• Talks excessively

• Blurts out answers before a question is completed

• Struggles to wait in line

• Interrupts or intrudes on others

A third variety of ADHD is diagnosed if a person experiences several symptoms of both aspects. A child or adult can lean one way or the other in the mix of attention issues and hyperactivity, which can change over time. Importantly, any of the above symptoms can be on display at times in adults and especially in children who nonetheless do not meet the clinical definition of ADHD, so a formal diagnosis is vital before any treatment is suggested. 

There is no single test for ADHD, and any person with the condition might have their own mix of symptoms (APA, 2022).

Recognition of the disorder we now call ADHD began a century ago, and definitions evolved as the medical community learned more into the 1980s. Some of the milestones (CHADD, n.d.): 

• During the global influenza pandemic of 1918-19, some children had fevers so high it changed their brains, affecting certain functions. As doctors started paying close attention beyond cases of flu, they realized that other children who hadn’t run high fevers showed similar functional difficulties (Swanson, 2020).

• By the 1960s, researchers started recognizing hyperactivity in some, but not all, kids with these symptoms and the terms ADD and ADHD co-existed.

• In the 1980s, hyperactivity symptoms were seen as one aspect of ADHD symptom, not a defining symptom. 

While the term ADD is still often used, experts no longer consider it to have formal medical meaning. 

About 8.7% of U.S. adolescents ages 13 to 18 have been diagnosed with ADHD at some point, and most children carry the disorder into adulthood (NIMH, n.d.). Heredity plays a role, but there can be other causes, none of which are well understood. ADHD can be diagnosed by a psychiatrist, psychologist or primary care physician, or pediatrician (Magnus, 2020). 

Treatments for ADHD are similar for adults and children, involving behavioral therapy and various medications. There is no known cure or prevention (AAP, 2019). 

If you hear someone use the term ADD, assume it’s shorthand and synonymous with ADHD. It’s your call whether to let them know it’s not a thing anymore.

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Current version

April 29, 2021

Written by

Robert Roy Britt

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.