Understanding The Three Different Types Of ADHD

Many people have moments when they have trouble focusing, lose track of time, or act impulsively, but an individual with attention-deficit/hyperactivity disorder (ADHD), previously known as attention deficit disorder (ADD), experiences these symptoms so consistently and severely that it substantially interferes with their life. More than simple forgetfulness or trouble concentrating, ADHD is a chronic, neurobiological condition that can last a lifetime and can have profound impacts if undiagnosed.

While ADHD is classified as a single disorder, there are three distinct clusters: inattentive, hyperactive-impulsive, and combined type ADHD. Each type is diagnosed according to a specific configuration of mental and behavioral symptoms, based on the degree to which the symptoms cause impairment.

Historically, there was a common misconception that people outgrow ADHD. Now we know that, in over 60% of cases, symptoms continue after the age of 18. And symptoms may also display differently in adulthood than in childhood. For example, difficulty controlling impulses may shift from speaking out in class to impulsive decision-making or adopting high-risk activities. Or daydreaming in school may change into daydreaming and difficulty paying attention in meetings. Additionally, those with high-functioning ADHD may struggle to recognize these common symptoms, even if they’re pervasive and disruptive.

Understanding the three types of ADHD can help you better understand and manage your own ADHD symptoms.

Hyperactive-impulsive type

This type of ADHD presents with a lot of the "classic" hyperactive and impulsive symptoms that people associate with the condition, such as risk-taking, fidgeting, and an inability to sit still. Sometimes, what starts as a compulsive need to move your body as a child may turn inward and become an inability to stop your racing thoughts as an adolescent or adult. 

As an adult, impulsive symptoms may be most noticeable. Impulsive type ADHD could present as buying something you can't afford or consistently speaking unprofessionally with a supervisor (despite internal attempts not to), for example. 

If you have this type of ADHD, you may have difficulty thinking about the consequences of your actions. This can lead to difficulties with work, relationships, and other areas of your life. An individual with this subtype may frequently interrupt others during a conversation, take dangerous risks, and seek stimulation in unhealthy ways.

Since hyperactive and impulsive behaviors tend to be more obvious in childhood, this subtype of ADHD is often caught early. However, that's not always the case, especially if the individual exhibits relatively mild hyperactivity and impulsivity.

Signs of hyperactive-impulsive ADHD include:

• Trouble sitting still for long periods; fidgets a lot

• Fast speech; frequently interrupts others

• Doesn't appear to consider the consequences of their actions

• Acts impulsively, including when driving, spending, or in relationships

• Chronic impatience; difficulty waiting

• Feelings of restlessness 

Inattentive type

An individual with inattentive type ADHD may have difficulty maintaining focus on routine tasks or conversation, be frequently distracted, make mistakes, or otherwise struggle to pay attention. Inattentive ADHD may go undiagnosed for years since most children with ADHD-related inattentive behaviors don't disrupt the classroom. Instead, they’re often labeled as “lazy” or “unmotivated,” rather than “troublesome.”

In adulthood, this subtype can manifest in various ways. For example, you may have difficulty completing work duties, meeting deadlines, or focusing on individual tasks. You probably won't experience many impulsive behavior or hyperactivity symptoms, but the condition can still create unnecessary stumbling blocks.

Inattentive ADHD used to be referred to as attention deficit disorder (ADD), although the term is no longer used. Primarily, inattentive ADHD is thought to be the least common type of ADHD.

Signs of inattentive ADHD include:

• Difficulty following instructions and finishing tasks

• Trouble concentrating; forgetfulness

• Getting distracted easily

• Chronic boredom

• Occasional extreme focus ("hyperfocus") on a stimulating task

• Difficulty following a conversation

• Frequently losing items

ADHD combined type

The third—and most common—type of ADHD is combined type ADHD. As the name suggests, this form of ADHD includes symptoms from both the inattentive and hyperactive-impulsive groups. To be diagnosed with combined ADHD, you need to have a combination of at least five of the symptoms from both categories. You may not display every symptom, but there will be sufficient evidence of both types.

Other ways ADHD can vary

Mild ADHD might not require intensive treatment. However, as with many medical conditions, people with all forms of ADHD can still benefit from a combination of behavior therapy, support groups, and medication.

What causes attention-deficit/hyperactivity disorder (ADHD)?

People with ADHD have lower levels of the neurotransmitter dopamine in the area of the brain responsible for impulse control, attention, and other so-called "executive functions." This causes difficulty controlling behavior, comprehending long-term consequences, stifling impulses, and sustaining attention. Brain imaging has shown that the brains of people with ADHD aren't always "on, " and it takes a higher level of stimulation in this area to get them there. This is why stimulant medication can be effective.

While a great deal of research has been performed to discover the cause of ADHD, mostly in pediatric patients, we're still not sure of the exact cause, and it’s likely that multiple elements play a role. Additionally, different types of ADHD do not appear to have different causes. ADHD has been shown to have a strong genetic component, and it's not uncommon for adults to seek an evaluation after their children receive a diagnosis. Exposure to alcohol, tobacco, and illegal substances during pregnancy may increase a child’s chance of developing ADHD.

If you are struggling with substance use, contact the SAMHSA National Helpline at (800) 662-4357 to receive support and resources. Support is available 24/7.

Video games, excessive TV, and other sources of high stimulation have not been shown to cause ADHD. While many people used to believe excessive consumption of sugar caused ADHD, this is also not the case. Rather, people with ADHD are probably more likely to hyperfocus on these activities because they’re highly stimulating.

A link between exposure to pesticides has been suggested as a cause for increased rates of ADHD in recent years, but more research is needed to make a definitive conclusion.

How do you diagnose ADHD?

As we continue to learn about this unique condition, more and more adults are getting their suspected ADHD diagnosed. Whether it's at the advice of friends and family, after a problem such as a car accident, or just being fed up with late appointments and disorganization, something drives many individuals to seek an ADHD diagnosis later in their lives.

ADHD is diagnosed using the latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the manual used as the official resource for determining the criteria for various mental disorders. Adults must regularly display five or more of the symptoms outlined in the DSM under one of the subtypes to be formally diagnosed. Moreover, evidence of these symptoms should be present before age 12.

A formal diagnosis of ADHD is made by a psychiatrist, psychologist, or another health professional with experience in diagnosing developmental disorders. Complete diagnosis may take several appointments, depending on the provider. They will perform an in-depth interview with you, asking questions about your symptoms and how they affect you to get a detailed history.

Not everyone who displays hyperactivity or inattentiveness has ADHD, of course. Some people just are more energetic or disorganized than others. The diagnosis of ADHD depends on the length of time the symptoms have been present and—critically—the degree to which the individual is negatively affected. Other conditions that can mimic ADHD, such as depression or OCD, need to be ruled out as well. These conditions can also coexist with ADHD, and, if that is the case, may need separate treatment.

Treatments for all types

If you are diagnosed with any type of ADHD, many effective treatments are available to help you manage the condition. The better you understand your particular type of ADHD, the better you can customize your treatment.

Talk therapy

For children and teens, behavioral interventions such as therapy are usually attempted before medication. Most adults with ADHD also benefit from working with a therapist to help them develop strategies for managing their symptoms. Cognitive behavioral therapy (CBT) is the most researched form of talk therapy for ADHD and involves recognizing and changing negative thought patterns and behaviors.

Medication options

Stimulant medication is approved to treat the three types of ADHD in adults as well as children age six or older. Stimulants work by increasing the amount of dopamine and norepinephrine in certain parts of the brain that can increase focus, improve working memory, and direct impulse control.

Nonstimulant medication is also available for those who don't respond well to stimulants. This medication must be taken for several weeks before the desired effect is achieved.

Should you try medication?

The choice to try medication is always up to the individual. Stimulants can be effective in up to 80% of cases, and the risk of side effects is generally quite low. However, many people choose to forgo medication for reasons ranging from personal preference to contraindicating medical conditions. It's up to you, and there exist many lifestyle changes and behavioral modifications that can help you effectively manage your adult ADHD with or without medication.

Working with a therapist

Some people with ADHD may experience difficulties managing in-person therapy appointments. After all, symptoms of the condition, like disorganization and forgetfulness, can make it challenging to show up to these office visits on time. Online therapy is another option that might help. Some people with ADHD and other mental health conditions find internet-based treatments to be more convenient and easier to stick to.

This type of treatment protocol has been found to be effective in treating ADHD as well. A 2022 meta-analysis evaluated the effects of online therapy on individuals diagnosed with the condition. The outcome indicated a positive effect on both attention deficit and social function.