Despite its name, attention deficit hyperactivity disorder (ADHD) involves more than trouble focusing and impulsivity. It’s characterized by symptoms that fall into two main categories: inattention and hyperactivity/impulsivity. According to the DSM-5, there are nine identifying symptoms within each of these distinctions. 

What are the nine symptoms of ADHD?

To meet the diagnostic criteria for ADHD, a person only needs to have six out of nine symptoms present in either the inattention or hyperactivity/impulsivity categories, for at least six months. The specific criteria and the number of symptoms required for a diagnosis can vary depending on the subtype of ADHD (predominantly inattentive presentation, predominantly hyperactive-impulsive presentation, or combined presentation) and the diagnostic guidelines used by healthcare professionals.

Symptoms of inattention

Inattention relates to executive functioning such as the ability to complete tasks, remember details, and stay focused. Someone who exhibits a pattern of inattention:

  1. Frequently misses details and makes careless mistakes
  2. Struggles to maintain focus
  3. Doesn’t listen when spoken to directly
  4. Fails to complete assignments and tasks
  5. Is not organized
  6. Procrastinates, especially on difficult tasks 
  7. Frequently loses things
  8. Is easily distracted
  9. Is very forgetful 

Symptoms of hyperactivity/impulsivity

Many of the characteristic behavioral issues that are associated with ADHD fall under the hyperactivity and impulsivity category. 

  1. Frequent fidgeting or squirming
  2. Stands (out of their seat) at inappropriate times
  3. Sporadic movements and restlessness
  4. Difficulty engaging in activities quietly
  5. Seemingly unable to sit still
  6. Chatterbox
  7. Blurting out answers
  8. Impatient
  9. Frequently interrupts others

What are the three types of ADHD?

Depending on the combination of symptoms exhibited, there are three subtypes of ADHD that a person can have: combined presentation (ADHD-C), predominantly inattentive presentation (ADHD-PI), and predominantly hyperactive-impulsive presentation (ADHD-PH).  

A combined presentation is someone who exhibits an equal number of symptoms from both ADHD categories. Someone who mostly exhibits symptoms of inattentiveness may appear daydreamy and disorganized, rather than fidgety or restless. On the contrary, key characteristics of a hyperactive-impulsive type of ADHD are that a person struggles to complete a task without interruptions, might frequently interrupt others, and appears to be particularly impatient.

Symptoms of ADHD in adults vs. children

Many of the tell-tale signs of ADHD, particularly those in the hyperactivity/impulsivity category are based on departures of accepted behavior in a classroom setting. Translation: when a child is routinely “acting out” in class. Naturally, those and many other ADHD behaviors are a lot harder to identify outside of this setting, especially for adults. 

While the core symptoms of inattention, hyperactivity, and impulsivity are consistent, the way these symptoms manifest may vary due to developmental and life stage differences. As children with ADHD transition into adulthood, their symptoms may evolve or become less overt. 

Since ADHD presents differently in adults and children, the nine symptoms from the two types of behavioral patterns may be of limited use when trying to diagnose someone 17 years or older. 

Inattention: Child vs. Adult

Inattention and executive functioning difficulties sometimes become more prominent in adults but can be more difficult to detect. 

Inattention in a child is identified through things like sloppy schoolwork, lost school supplies, or failure to pay attention during lessons. In an adult, these behaviors are very similar but can easily be misattributed as someone simply being busy or overwhelmed, rather than having a mental disorder.

An ADHD adult with inattention appears disorganized and has poor time management; forgets appointments; and has difficulty paying attention to details. Adults with ADHD often face challenges related to work, relationships, time management, and self-regulation.

Hyperactivity/Impulsivity: Child vs. Adult

The physical symptoms of ADHD (hyperactivity) like fidgeting and being unable to sit still usually recede with age — they are still present, but less pronounced. Instead, impulsive behaviors are more likely to be prominent, in part because adults have much greater agency than children. These impulses can look like reckless spending or substance abuse.

Diagnosing ADHD symptoms and treatment

Diagnosing ADHD in adults can be more challenging due to the differences in symptom presentation, and is even more difficult if other mental health conditions are present. The best way to determine ADHD in a child or an adult is a comprehensive evaluation by a qualified healthcare professional. 

A professional won’t just confirm an ADHD diagnosis, but evaluate which category of nine ADHD symptoms a person exhibits more of to accurately diagnose what type of ADHD someone has. 

There is no permanent cure for ADHD, but it is highly manageable. Upon an ADHD diagnosis, a mental health professional can recommend an appropriate treatment plan of a combination of therapy, medication, and behavior management strategies.