ADHD, forgetfulness and working memory in adults

Walking into a room and forgetting why. Agreeing to send a document, then realizing three days later you never did. Losing your keys, your badge and your train pass in the same week. Adults with ADHD often describe forgetfulness as one of their most frustrating symptoms, and it is easy to wonder whether it is ADHD, stress, age or something else. This article explains what kind of forgetting is linked to ADHD, what memory research in adults shows, what it does not show, and what other causes a clinician will consider.

Forgetfulness is part of the ADHD criteria

Being "often forgetful in daily activities" and often losing things needed for tasks are two of the nine inattention symptoms in the diagnostic criteria, as listed in a 2025 review of adult ADHD in World Psychiatry. The National Institute of Mental Health says that in adults, ADHD symptoms can lead to trouble remembering daily tasks and frequently losing things or being forgetful in activities.

NIMH also notes that many people show some of these behaviors some of the time. In ADHD they are more severe, frequent and persistent, show up across multiple situations, and interfere with daily life. That distinction matters more than any single lapse. For the full set of criteria, see inattentive ADHD in adults.

Not all memory is the same

The forgetting linked to ADHD is mostly not about losing old memories. Research points to a few specific systems.

What the research shows

• Working memory differences persist into adulthood. A 2013 meta-analysis in Neuropsychology pooled 38 studies of adults with ADHD and found moderate-sized differences from healthy controls in both verbal (phonological) and visual-spatial working memory. The authors concluded that working memory deficits persist into adulthood.
• Working memory is one of the larger cognitive differences. A 2018 review of 34 meta-analyses found people with ADHD did worse than controls in almost every cognitive domain measured, with working memory among the domains showing the largest average effects.
• "Remembering to remember" is affected. In a 2019 study, 29 adults with ADHD recalled and carried out fewer of their own real-life intentions than 24 controls, and those everyday memory lapses helped explain the link between ADHD symptoms and procrastination.
• Planning is often the weak link. A 2013 study of 45 unmedicated adults with ADHD and 45 matched controls found a large impairment in planning a delayed task, with only small differences in recalling the plan or starting and carrying it out.

That last finding is useful. For many adults with ADHD, the problem is less that the memory is gone and more that the task was never set up in a way that would bring it back at the right moment. The overlap with planning and organization is covered in executive dysfunction and ADHD.

What the research does not show

• That every adult with ADHD has a working memory deficit. The 2025 World Psychiatry review notes that average differences on neuropsychological tests are much smaller than differences in symptoms, and that test performance may differ little from controls in many people with ADHD.
• That a memory test can diagnose ADHD. The same review states there are no tests or biomarkers with enough predictive power to diagnose ADHD, and that UK guidance did not endorse any neuropsychological test for diagnosing adults. ADHD is diagnosed through a clinical evaluation of symptoms, history and impairment. The difference between an evaluation and testing is explained in clinical evaluation or neuropsychological testing.
• That forgetfulness means ADHD. Memory complaints are common and have many causes.

Other causes a clinician will consider

An evaluation for adult ADHD looks at what else could explain memory problems, or what could be adding to them:

• Depression. NIMH lists difficulty concentrating, remembering or making decisions among the common symptoms of depression. See ADHD and depression in adults.
• Sleep. NIMH notes that sleep problems affect up to 70% of adults with ADHD, so sleep is one of the first things an evaluation asks about.
• Timing of onset. ADHD symptoms must have started before age 12, according to NIMH. Forgetfulness that began recently, in midlife, after an illness or with a new medication raises other questions. Hormonal transitions are discussed in ADHD, perimenopause and menopause.
• Medical issues, medications, alcohol and cannabis. These are part of the health history taken at any careful evaluation.

The National Institute on Aging advises talking with a doctor about noticeable changes in memory, and lists signs such as asking the same questions over and over, getting lost in places you used to know well, and becoming more confused about time, people and places. That pattern is different from the long-standing, everyday forgetfulness described in the ADHD criteria, and it should be raised with a primary care doctor.

Practical supports adults use

A 2017 qualitative study of 32 adult ADHD outpatients found that before diagnosis, many had built their own compensation strategies. Organizational strategies were the most common, including smartphones, electronic calendars and reminder apps, and building routines. These are not treatment, but they line up with the research above: if planning and "remembering to remember" are the weak points, it helps to move reminders out of your head.

• Set the reminder at the moment you agree to the task, not later.
• Tie reminders to a place or action ("when I get to the car") as well as a time.
• Keep keys, wallet and badge in one fixed spot by the door.
• Write multi-step instructions down instead of holding them in mind.

When to talk to a clinician

Forgetfulness is worth discussing with a clinician when it is frequent, has been there since childhood, shows up at home and at work, and is causing real problems, such as missed deadlines, late bills or lost items that cost money. The adult ADHD self-test can help you organize what you notice before an appointment, but it cannot diagnose ADHD or rule out other causes.

Dr. Shershow is a psychiatrist who focuses on adult ADHD and sees adults located in New York or New Jersey. His evaluation covers current symptoms, childhood, school and work history, health, sleep and substances, and other explanations, and ends with what it found and the treatment options that fit. See ADHD testing in NYC or ADHD testing in New Jersey, or call the office.