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Adult-Onset ADHD: Understanding Symptoms, Causes, and Real Solutions

Adult-Onset ADHD: A Complicated Situation with Real Solutions

Written by Dr Marc Mooney, PhD, LP

Attention-Deficit/Hyperactivity Disorder (ADHD) is a brain-based condition recognized since the 1960s. It’s common and often joked about—“I forgot to buy milk. I must have ADHD!”—but for people living with it, or with difficulties managing focus and follow-through, it’s no laughing matter. While many are diagnosed in childhood, a significant number don’t seek help until adulthood.

Adults seeking ADHD evaluations aren’t looking for labels—they’re trying to function better, show up for others, and succeed in daily life. Trouble with focus and organization in adulthood is real, no matter the cause. The right treatment or approach, however, depends on what’s driving the problem.

ADHD: A Challenge of Mental Management

The “H” in ADHD—hyperactivity—gets most of the attention, but ADHD is really about something broader: how our brains manage tasks, focus, and behavior. These skills are called executive functioning, and they include:

  • Working memory – the mental scratchpad we use to hold information briefly, like remembering a phone number.
  • Cognitive flexibility – the ability to shift focus or adapt when things change.
  • Impulse control – the ability to stop ourselves from blurting something out or doing something impulsive.

These abilities naturally decline with age, but in ADHD, they often cause problems earlier. Many people with ADHD think they have a “bad memory,” but it’s often their working memory (or “remembering to remember”) that’s at fault. Our modern, distraction-heavy world—full of phones, notifications, and multitasking—only makes things harder.

Why ADHD Was Once Thought of as a Childhood Disorder

Back in the 1960s, ADHD was considered something only kids had. Even today, official criteria require that some symptoms began in childhood. But researchers now recognize that some adults seem to experience ADHD symptoms for the first time later in life.

One way to understand this is through the diathesis-stress model. Some people have a hidden vulnerability, and when life becomes more demanding—like starting college or a high-pressure job—that weakness shows up. Imagine someone with strong bones and someone with weak bones. The person with weaker bones might break a leg from a minor fall, while the other might only get hurt during a major accident. The same goes for ADHD: some people’s brains may only struggle when life becomes overwhelming.

Why Didn’t It Show Up in Childhood?

If ADHD can surface later in life, why wasn’t it diagnosed earlier? There are several possible explanations:

  • Quiet symptoms. Kids with mostly inattentive symptoms might not get flagged because they’re not disruptive.
  • Missed signs. Parents and teachers may mistake the issues for laziness or personality quirks.
  • Stigma or misunderstanding. Some families avoid diagnoses or fear that medication is the only treatment.
  • Financial barriers. Even when concerns arise, cost or lack of access can prevent evaluations.
  • Structured environments. Highly organized homes can mask symptoms until independence—like college—reveals them.

Why Adults Start to Suspect ADHD

Adults might begin to wonder about ADHD when they face new challenges and find themselves struggling in unexpected ways:

  • College: The leap from high school to college—with tougher academics and less structure—can overwhelm students who never had to study hard before.
  • Work: A first job requires self-discipline, time management, and stress tolerance. Without those skills, new hires may feel disorganized or burned out.
  • Parenthood: Caring for children is rewarding but mentally draining, leaving parents feeling scattered or forgetful.
  • Other mental health conditions: Depression and anxiety can mimic ADHD by affecting focus and memory.
  • Hormonal or age-related changes: Menopause and normal cognitive shifts with age can make attention issues worse.

Reframing Expectations

Many people seek help because they feel they’re underperforming. That drive to improve is admirable, but expectations can sometimes be unrealistic:

  • “I should get straight As.”
  • “I must never forget anything.”
  • “My work should always be perfect.”

No one meets every expectation all the time. That doesn’t mean you have ADHD—or that you don’t. It just means you’re human. A psychological assessment can help clarify what’s really going on. If you do have ADHD, treatment and self-awareness can help you function better. If something else is behind your struggles, other tools or strategies may work better. Either way, self-compassion and curiosity are the real starting points for growth.

About the Author: Dr. Marc Mooney, PhD, LP, is a licensed clinical psychologist specializing in psychotherapy and psychological assessment. He completed his doctorate at the University of Minnesota and has been in practice since 2007. You can learn more about Dr. Mooney here: https://expansemn.com/marc-mooney/ or reach out to Expanse and schedule an initial visit: www.expansemn.com