Mental health professionals no longer diagnose ADD. Instead, they diagnose one of three types of ADHD: inattentive, hyperactive-impulsive, or combined — based on symptoms.

Attention deficit disorder (ADD) is an outdated term for what experts now call attention deficit hyperactivity disorder (ADHD).

The term ADD first appeared in the third edition of the “Diagnostic and Statistical Manual of Mental Disorders (DSM-3),” a reference manual that helps mental health professionals diagnose mental health conditions.

Experts separated the condition into two subtypes:

  • ADD with hyperactivity
  • ADD without hyperactivity

When the American Psychiatric Association released a revised edition in 1987, they combined these two subtypes into one condition: ADHD.

Today, ADHD is one of the more common childhood mental health conditions. The Centers for Disease Control and Prevention (CDC) says that about 9.4 percent of children and adolescents (just over 6 million) in the United States have ADHD.

Adults can have ADHD, too. According to a 2021 review, nearly 2.6 percent of adults globally have persistent ADHD from childhood, while about 6.7 percent of adults have symptoms of adult ADHD.

Since these estimates come from reported symptoms and diagnoses, some believe the real prevalence of ADHD could be higher.

Experts have identified three types of ADHD, based on the main symptoms involved:

  • inattention
  • impulsivity and hyperactivity
  • a combination of inattention and hyperactivity

Inattentive type

Originally, ADD described the inattentive type of ADHD.

A doctor or mental health professional might have diagnosed ADD when someone had persistent symptoms of inattention and distractibility, but few signs of hyperactivity or impulsivity. Now, they’d most likely diagnose ADHD with a predominantly inattentive presentation.

Symptoms of the inattentive type include:

  • easy distractibility
  • frequent forgetfulness in daily life
  • trouble paying attention to details or listening when other people speak
  • difficulty concentrating on tasks or activities
  • trouble following instructions and completing tasks as directed
  • a tendency to lose focus or get sidetracked easily
  • difficulty staying organized or managing time
  • a tendency to put off or avoid tasks that require long periods of mental effort, such as homework or work projects
  • a habit of losing vital things needed for daily routines and activities

These signs might show up at school, work, home, or in personal relationships.

With this type of ADHD, you (or your child) might:

  • have trouble keeping track of special dates like birthdays and anniversaries along with due dates for work assignments and bill payments
  • find it difficult to complete tasks on time, and procrastinate on schoolwork, chores, or even projects you enjoy
  • have a hard time paying attention, even to things that interest you, like the latest book in a favorite series or a friend’s description of a recent trip
  • make frequent mistakes in your work

Hyperactive type

This type of ADHD, also called the hyperactive-impulsive type, involves symptoms of hyperactivity and impulsivity.

Key symptoms include:

  • difficulty sitting quietly, remaining still, or staying in one place
  • excessive talking
  • difficulty waiting patiently or taking turns
  • frequent fidgeting, squirming, or tapping hands and feet
  • trouble staying seated in school, work, or other situations
  • persistent feelings of restlessness, which might show up as a tendency to run or climb in inappropriate situations
  • trouble playing quietly or participating in relaxing activities
  • a habit of finishing others’ sentences or giving an answer before someone finishes asking a question
  • a habit of interrupting others, intruding on conversations and activities, or using others’ belongings without permission

Again, these symptoms will show up in multiple areas of life. You might, for example:

  • need to pace the room or move around a lot, or feel as if you can’t stop moving
  • have trouble waiting in long lines, traffic, or for appointments
  • jump in with your own thoughts and ideas when others are talking
  • make decisions or shop impulsively
  • have emotional outbursts, or find it hard to manage extreme or intense emotions

Combined type

People with the combined type of ADHD have symptoms from both the inattentive and hyperactive-impulsive categories.

Children under the age of 17 need to have at least 6 symptoms from each category. Adults ages 17 and older need to have at least 5 symptoms.

Some experts suggest that the combined type of ADHD is more common than the other two types, especially in adults.

In an older study of 107 adults with ADHD:

  • 62 percent of adults with ADHD had the combined type
  • 31 percent had the predominantly inattentive type
  • 7 percent had the hyperactive-impulsive type

But a more recent review explored the prevalence of ADHD in children and adolescents in Africa. They found evidence to suggest combined ADHD was the least common type.

According to data from 12 studies:

  • 2.95 percent of children and adolescents with ADHD had the predominantly inattentive type
  • 2.77 percent had the hyperactive-impulsive type
  • 2.44 percent had the combined type

It’s possible that parents and teachers may simply find signs of combined ADHD easier to recognize. As a result, people with the combined type could have a better chance of getting the right diagnosis, since their symptoms align with behaviors most people associate with ADHD. This could give the perception that combined ADHD is more common than other types of ADHD.

A diagnosis of ADHD requires more than the key symptoms of inattention, hyperactivity, or impulsivity.

Not only do children need to have 6 or more symptoms (5 or more for adults) for at least 6 months, they also need to:

  • have some symptoms before the age of 12
  • show symptoms in at least two different settings, including at school, home, work, with friends, or during other activities
  • have symptoms severe enough to interfere with function at school, work, or in social situations and affect quality of life

Before making a diagnosis of ADHD, a mental health professional will also rule out other mental health conditions, including:

Parents and teachers may not always notice symptoms of ADHD in children, especially when those symptoms are less easy to observe and don’t disturb others.

Research from 2020 notes, for example, that inattentive symptoms often go unrecognized, especially in girls, since these symptoms generally don’t disrupt others. A child with inattentive ADHD might seem dreamy or distant. They might also seem intently focused on what looks like class notes when they’re actually doodling or zoning out.

If you don’t get a diagnosis in childhood, you might not seek support unless you begin to have problems at work or school, or in your relationships with friends and romantic partners.

Many people with ADHD find their symptoms improve with age. That said, if you never get the right diagnosis or treatment, you might continue to find those symptoms difficult to cope with. As a result, you might feel as if they’re getting worse over time.

Other mental health symptoms, like anxiety and depression, not to mention the everyday stressors that come with being an adult, can also affect your symptoms. These factors could lead to changes in the symptoms you experience.

Generally speaking, the symptoms of ADHD remain much the same for children and adults. But if you have more responsibilities as an adult, your symptoms could have more of an impact on your life.

  • In childhood, it might matter less if you frequently forget dates or lose your keys, if you have parents and siblings to help you out.
  • As an adult, forgetting to pay your rent, losing your wallet, or frequently showing up late for work could have more serious consequences.

Learn more about key signs of ADHD in adults.

You might have heard ADD (the inattentive type of ADHD, that is) described as a “less severe” form of ADHD, or something along those lines.

In reality, though, none of the three ADHD types are necessarily any more or less severe than the others.

Still, symptom severity absolutely can differ from person to person, even in the same family. You and a sibling could both have the combined type of ADHD, for example, but one of you may have milder symptoms.

The so-called “milder” inattention symptoms can still have a big impact. These symptoms may not affect your conduct or behavior at school or work in any obvious way. But you might still face plenty of difficulties focusing, staying organized, or completing tasks correctly and on time.

These symptoms might not improve if they go undiagnosed and untreated, so they can last into adulthood and continue to create challenges in your life.

Getting the correct diagnosis and finding the best treatment for you can go a long way toward helping you manage these symptoms effectively.

Learn more about treatment options for ADHD.

Mental health professionals no longer diagnose ADD. Instead, they’ll diagnose one of three types of ADHD — inattentive, hyperactive-impulsive, or combined — based on your (or your child’s) symptoms.

Sharing all of the symptoms you notice with your therapist or doctor can help them to arrive at the correct diagnosis.

At the end of the day, what matters most is finding a treatment that works for you, whether that involves therapy, medication, or both. Determining the type of ADHD you have can put you one step closer to finding an effective treatment.