Many adults think they have undiagnosed ADHD. Here's what to know.

ADHD, or attention deficit hyperactivity disorder , could be more common in adults than we realize.

The Centers for Disease Control and Prevention estimates that about 15.5 million U.S. adults have received a diagnosis of ADHD at some point in their life. But according to a new survey from The Ohio State University Wexner Medical Center and College of Medicine, about 25% of American adults suspect they have undiagnosed ADHD, and only about 13% have shared their suspicions with their doctors.

Mental health experts worry that self-diagnosis can lead to the wrong treatment.

If someone suspects they have ADHD, they should definitely see a doctor, Dr. Céline Gounder, CBS News medical contributor and editor-at-large for public health at KFF Health News, said on "CBS Mornings" Tuesday .

"The symptoms of ADHD can be more subtle in an adult. There's a lot of overlap with other mental health as well as other medical conditions, and how you treat it may be different depending on what mix of symptoms, what other overlapping syndromes you might have," she said.

What is ADHD?

ADHD is a neurodevelopmental disorder characterized by issues with inattention, restlessness, hyperactivity and impulsivity, Gounder explained.

The CDC describes it as "a common childhood disorder that can continue into adulthood," but notes there is "limited information about diagnosis and treatment in adults."

"The reason there's a lot of stigma around this is we tend, as a society in general, to blame the symptoms of many medical issues, from obesity to addiction, on character flaws and are missing the point that this is actually a real medical condition," she said.

ADHD in adults

While it's more likely that ADHD develops in childhood and may have gone under the radar, there are some people who do seem to develop some of these symptoms later in life, according to Gounder.

"With adults, we're more mature, we're better able to mask some of the symptoms and cope with some of the symptoms. And so it may be not as obvious in an adult," she said.

Gounder said signs that may point to ADHD in adults include:

• Difficulty finishing projects or focusing on tasks
• Difficulty with organizational skills and time management
• Being fidgety, feeling restless
• Interrupting others, talking excessively

The Mayo Clinic also notes people may also experience impulsive decision-making, irritability and difficulty managing emotions or frustration.

"Those are some of the behaviors that we see. But again, there's a lot of overlap with other things, so you really do need somebody who knows how to diagnose this," Gounder said.

ADHD treatment

Treatment of ADHD typically includes a combination of therapy and medication.

CBT, or cognitive behavioral therapy, teaches you how thoughts, feelings and behaviors interact and "how to, in a sense, override what might be your initial impulse in a certain situation," Gounder explained.

Medications may include stimulants like Adderall , Vyvanse, Ritalin or Concerta.

"There are also some medications that are not stimulants, they just take a little longer to kick in," she said.