With 15.5 million U.S. adults currently diagnosed with ADHD, there is a growing focus on warning signs of the disorder.

Attention-deficit/hyperactivity disorder is a “developmental disorder marked by persistent symptoms of inattention, hyperactivity and impulsivity,” as defined by the National Institutes of Health.

“ADHD is often misunderstood as just being overly distracted or hyperactive — in reality, it’s a neurodevelopmental condition that affects focus, emotional regulation, time management and impulse control,” Lisa Anderson, a licensed clinical social worker and clinical director at Brooks Healing Center in Tennessee, told Fox News Digital.

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More than half of the adults with attention-deficit/hyperactivity disorder didn’t learn they had the condition until adulthood, according to data from the Centers for Disease Control and Prevention (CDC).

Fox News Digital spoke with multiple mental health experts, who identified the most common signs and symptoms of ADHD in adults.

1. Impulsive behaviors

Adults with ADHD have difficulty managing impulsivity, according to Zoë Kahn, a licensed psychotherapist and ADHD therapist in Pasadena, California.

“This can look like blurting out answers in a classroom setting, interrupting in conversation and difficulty thinking through the long-term consequences of choices,” she told Fox News Digital.

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Impulsivity can also lead to making snap decisions without considering long-term consequences, Anderson added. 

“It might also manifest subtly, like overspending on impulse purchases or having trouble waiting your turn in group discussions,” she said.

2. Difficulty focusing or staying on task

Procrastination and difficulty following through on tasks are common signs of ADHD, Anderson noted. 

“You might struggle to start tasks, even when vital, or abandon them halfway through,” she said. “You might jump between tasks without finishing anything or focus on smaller, less urgent tasks while the bigger, more critical ones remain untouched.”

“It’s a persistent challenge that affects work, relationships and daily responsibilities.”

It’s not about laziness, Anderson noted, but about feeling overwhelmed by what needs to be done.

“ADHD-related daydreaming is persistent and often disruptive, especially when it happens during crucial tasks or conversations,” she said.

“This isn’t just about occasionally zoning out during a long meeting — it’s a persistent challenge that affects work, relationships and daily responsibilities.”

3. Trouble with time management

People with ADHD may struggle to manage their schedules, often underestimating how long it will take to complete a project or reach a destination.

“Deadlines might sneak up on you, or you might feel perpetually behind on tasks, no matter how early you started,” Anderson told Fox News Digital.

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“This can create a constant cycle of stress and underachievement, leaving you feeling frustrated with yourself.”

4. Mental fatigue

Mental fatigue and burnout are widespread in individuals with ADHD, according to Anderson. 

“The ADHD brain often works in overdrive, juggling competing thoughts and struggling to stay on track,” she said. 

“This constant effort to stay focused and organized can leave you feeling drained, even after relatively short periods of productivity.”

5. Forgetfulness

Another sign of ADHD in adults is general disorganization, Kahn said, which can lead to an inability to follow through on tasks, meet important deadlines, pay bills on time or keep appointments.

“The ADHD brain often works in overdrive, juggling competing thoughts and struggling to stay on track.”

They may also find themselves misplacing important items, like car keys.

“Adults with ADHD have a hard time finding and keeping focus, which could look like not paying attention in conversation, missing key details, being easily distracted in certain settings, or even focusing on the wrong details,” Kahn added.

6. Inability to sit still

People with ADHD often find themselves fidgeting and feeling generally restless, according to Dr. Michelle Dees, a board-certified psychiatrist at Luxury Psychiatry Clinic in Chicago.

“In adults, this may present as inner disquietude or incomplete calmness,” she told Fox News Digital.

Anderson reiterated this common symptom, noting that in children, it often takes the form of physical hyperactivity.

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“It often transforms into internal restlessness in adults, where you feel like you can’t fully relax or sit still without feeling jittery,” she said. “This constant sense of being ‘on edge’ can become exhausting over time.”

7. Relationship challenges

“Many adults with ADHD have difficulty maintaining relationships with others due to inappropriate social behaviors, such as frequently interrupting, losing interest in conversations, difficulty paying attention and forgetfulness,” Kahn noted. 

“You might forget to call friends back or forget about commitments to others, which can cause issues in your relationships.”

Emotional sensitivity often accompanies ADHD, according to Anderson. This can manifest as mood swings, irritability or heightened responses to minor frustrations. 

“Many people with ADHD describe feeling like their emotions are more intense and more challenging to control than those of others around them,” she added.

When to seek help

If you’ve experienced several of the above signs and they interfere with your daily life, experts recommend seeking help. 

“ADHD is not a flaw nor something to be ashamed of — it’s simply a different way of processing information and interacting with the world,” said Anderson.

The first step is to speak with a health care professional specializing in ADHD, such as a psychologist, psychiatrist or even your primary care physician, she suggested. 

“They can provide a proper evaluation and help you explore treatment options, including therapy, medication or lifestyle adjustments,” Anderson noted.

Potential solutions include mindfulness exercises and cognitive behavioral therapy (CBT), which can help people with ADHD to improve their organization, time management and emotion regulation, the same source stated. 

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“For many people, medication is also an essential part of managing ADHD, as it can help balance brain chemistry and improve focus,” Anderson added.

Brooke Bardin, a licensed clinical social worker and director of Clinical Quality Assurance in Los Angeles, pointed out that ADHD can sometimes be confused for other conditions.

“ADHD has overlapping symptoms with other disorders and is often comorbid with other diagnoses,” she told Fox News Digital. 

Anywhere from 40% to 70% of people with autism spectrum disorder also have ADHD, according to Bardin.

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It can also occur in tandem with learning disorders, anxiety disorders and mood disorders. 

“Because of this, it is important to be assessed by a psychiatrist or mental health clinician,” Bardin advised.

“ADHD is not a flaw nor something to be ashamed of — it’s simply a different way of processing information and interacting with the world.”

As you seek out the right support and strategies, Anderson emphasizes the importance of being kind to yourself.

“ADHD isn’t a limitation — it’s a unique way of experiencing the world, and with the right tools, you can learn to harness its strengths and work through its challenges.”