How Young Is Too Young To Know If Your Kid Has ADHD?

As someone who has had an anxiety disorder since I was a teenager, I've never been a stranger to overthinking things. Staying up late, my brain racing as I map out the day ahead or replay the previous one — it's been commonplace for me as long as I can remember. But, as any parent can attest, having a kid will raise your anxiety to a level you've never experienced. Whereas once my days were spent worrying if I'd said something stupid or made a dumb mistake, now I stay up half the night worrying about things like my child's development, whether they're enjoying pre-K, or getting too much screen time.

And recently, the onslaught of news about neurodivergency has brought a new spotlight to my anxiety. You see, ever since my kid was born, my husband and I have wondered if she may end up exhibiting signs of ADHD. The thought isn't out of nowhere: My husband was diagnosed with ADHD as a child, a diagnosis that he still works with daily.

As my daughter has gotten older, we've started picking up on small signs that she may also be showing early signs of ADHD. Of course, as she's a young child, we know that it's likely too early to officially diagnose her (plenty of her "signs," such as difficulty following instructions and impulsivity, can simply be attributed to her age). But with a genetic predisposition, it did make us start wondering... How young is too young to know if your kid has ADHD? For answers, I spoke with Melissa Gluck, Ph.D, at Gluck Psychology Collective.

At what age can you officially diagnose ADHD in children?

Gluck stressed that when a parent has a "nagging feeling that what you're seeing in your child isn't quite typical" or sees more intense and frequent behavior that's hard to manage, it's completely reasonable to be curious what is going on. However, she advised against jumping to conclusions or rushing into a diagnosis — instead, she recommends getting curious and learning more if you suspect your child may have symptoms of ADHD.

"You can't officially diagnose ADHD until around age 4, but many of the signs can show up earlier than that," Gluck explains. "It's not uncommon for parents (or daycare providers) to start noticing red flags as early as age 2 or 3."

As for why professionals usually wait, it's because a diagnosis requires a consistent pattern of behavior that's evident in more than one setting and has persisted for a minimum of six months. "While a busy, impulsive toddler doesn't automatically mean ADHD, if those behaviors are interfering with your child's ability to play, learn, or connect with others, and it's not getting easier with time, it's worth checking in with someone who can help you sort it out."

Early Signs of ADHD

The classic stereotype of someone struggling with ADHD can be a kid who is moving nonstop, their brain moving a mile a minute. While this can sometimes be the case (certainly it sounds a bit like how my husband was as a child), it's not the only early sign of ADHD to look out for.

Gluck shared that sometimes these signs can be quieter: "It's the child who seems like they're always daydreaming or just not quite with you. It's the half-finished puzzles, the zoning out mid-story, the forgotten instructions that you just gave 30 seconds ago."

Here were a few of the other signs or examples she's seen pop up when working with younger kids:

• Can't sit still, even during something they enjoy, their body's just always in motion
• Starts playing with blocks, then five minutes later, they're under the table with a crayon and no pants on
• Starts playing with blocks, then five minutes late, they're under the table with a crayon and no pants on
• Interrupts or talks over people constantly, not to be rude, their brain just jumps in before they can stop it
• Big feelings, fast, like melting down over the blue cup instead of the green one, and staying upset way longer than expected
• Struggles to fall asleep, or wakes up a bunch in the night, even though they're clearly exhausted

The Differences Between ADHD and Early Childhood Behavior

If you're a parent of young kids, you may read those examples and think to yourself, "Well, that sounds like any young kid." And Gluck shared that that is very much the case — all kids do at least some of this as a part of being little. All young kids are supposed to go through times where they have trouble staying quiet, managing big feelings, or waiting their turn. That's simply a regular part of childhood development.

Where it can sometimes differentiate is how much this happens. "If you're seeing a lot of this, a lot of the time, and especially if it's making everyday things harder than they need to be, then that's when it might be worth digging a little deeper," Gluck explains. "It's not about labeling your child. It's about understanding them better, so you can give them the kind of support that actually works for them."

ADHD in Boys vs. Girls

Another reason I think my husband and I have been so hyper-focused on understanding our daughter's behavior is that we had read a few reports that ADHD is often underdiagnosed in girls versus boys.

And Gluck shared that the signs girls and boys exhibit for ADHD can definitely be differentiated. "Boys are more likely to show the loud, high-energy kind of ADHD," Gluck shares. "They're the ones climbing furniture, getting out of their seats, or being told they need to 'sit still and focus.' Because those behaviors are hard to ignore, boys tend to get referred for evaluation earlier."

For girls, signs of ADHD can be exhibited differently. "They may be just as distracted or disorganized, but they're usually less disruptive," Gluck says. "Instead of bouncing off the walls, they're staring out the window, daydreaming, or quietly falling behind. Sometimes their ADHD is mistaken for anxiety, or they're just seen as shy or forgetful. As a result, many girls don't get diagnosed until much later, when academic or social struggles become harder to miss."

Trusting Your Instincts

Here's the thing — even though we as parents are wondering whether our daughter has ADHD, it's not us looking for a way to label things. For us, it's something we want to know so we can better understand and support our kid through her development.

I felt reassured talking to Gluck, who shared that it's important for parents to trust their gut when it comes to their kids. "If you've been wondering whether your child's behavior might be more than just typical development, trust that instinct," she tells us. "Remember, no one knows your child better than you do. Reaching out doesn't mean you're overreacting; it means you're taking a proactive approach. It means you care enough to understand what's going on so you can give your child what they need, whether that's reassurance, support, or a full evaluation."

As for where to start, she recommends speaking with your pediatrician. They can share the next steps to move forward. Depending on your kid's age, you can also talk with their teacher or daycare provider to see what they're noticing. From there, you can also look into a child psychologist or psychiatrist who specializes in early childhood.

"Remember, ADHD is not a reflection of bad parenting or bad behavior," Gluck reassures. "It's a difference in how the brain works, and when we understand that difference, we can support it. Kids with ADHD are bright, creative, and capable. They just need the right tools to help them shine."