Prospective Memory and ADHD: When "I'll Remember to Do That" Goes Wrong

If you have ADHD and often find yourself saying "I completely forgot I was meant to do that," you're not alone. Many people with ADHD struggle with prospective memory; the ability to remember to carry out planned actions in the future. Whether it's taking medication, calling someone back, or remembering to pick up milk on the way home, these seemingly simple tasks can be surprisingly difficult to complete.

Understanding why this happens and what can help is the first step toward working with your brain rather than against it.

What Is Prospective Memory?

Prospective memory is your ability to remember to do something at a specific time or in response to a particular cue. It differs from its opposite, retrospective memory, which involves recalling information from the past (such as remembering what you had for breakfast yesterday).

There are two main types of prospective memory:

Time-based prospective memory involves remembering to do something at a specific time, such as taking medication at 8:00 a.m. or calling someone at 3:00 p.m.

Event-based prospective memory involves remembering to do something when a particular situation arises, such as buying milk when you're at the supermarket or returning a book when you see your colleague.

Both types require you to hold an intention in mind while you're busy doing other things, then remember to act on that intention at the right moment. For most people, this happens relatively automatically. For people with ADHD, it's often where things go wrong.

How Does ADHD Affect Prospective Memory?

People with ADHD have more difficulty with prospective memory tasks than neurotypical people. This isn't about intelligence or caring; it's about how ADHD affects the brain systems involved in planning, monitoring, and executing future actions.

Several ADHD-related difficulties contribute to prospective memory problems:

Attention and distraction play a major role. Prospective memory requires you to monitor your environment for the right cues while doing other tasks. If your attention gets captured by something else, you might miss the cue entirely.

Working memory difficulties also interfere. You need to hold the intention in mind while juggling other information and tasks. When working memory is stretched thin, planned actions can simply slip away.

Executive function challenges, particularly in planning and organisation, make it harder to set up systems that support prospective memory. You might struggle to link actions to reliable cues or to create effective reminders.

Time perception differences can affect time-based prospective memory. Many people with ADHD have difficulty accurately estimating how much time has passed, making it harder to remember time-based tasks.

The result? You might genuinely intend to do something, but when the moment comes, the intention has vanished from your conscious awareness. It's incredibly frustrating, especially when others interpret it as a lack of care or unreliability.

Prospective Memory in Early Alzheimer's Dementia

Interestingly, prospective memory difficulties are also one of the earliest and most sensitive signs of Alzheimer's dementia. In my previous work with older adults, and through performing numerous dementia assessments, I often found that identifying prospective memory difficulties could be a helpful sign that cognitive abilities were starting to decline before more obvious difficulties emerged.

This creates an important distinction for clinicians. While both ADHD and early Alzheimer's can cause prospective memory problems, the underlying causes and patterns are different:

In individuals with ADHD, prospective memory difficulties are typically lifelong and often co-occur with challenges in attention, working memory, and executive function. People with ADHD often have strategies that help, and their prospective memory problems don't progressively worsen over time.

In early Alzheimer's, prospective memory problems represent a change from previous functioning and worsen gradually. These difficulties occur alongside subtle changes in other cognitive areas, even if they're not immediately obvious.

For adults being assessed for ADHD later in life, understanding this distinction is important for accurate diagnosis and appropriate support.

What Can Help?

The good news is that there are many practical strategies that can significantly improve prospective memory functioning for people with ADHD:

External reminders are your friend. Don't rely on your brain to remember; create external cues. Phone alarms, calendar notifications, sticky notes in strategic locations, and task management apps can all help bridge the gap between intention and action.

Link actions to existing routines. If you need to take medication daily, link it to something you already do consistently, like brushing your teeth or having your morning coffee. This creates a reliable cue that's hard to miss.

Use implementation intentions. Instead of just thinking "I need to call Mum," create specific if-then plans: "If I finish eating lunch, then I will immediately call Mum." This pre-commitment makes it more likely you'll follow through.

Reduce cognitive load. The more mental tasks you're trying to juggle, the more likely prospective memory will fail. Write things down, use external organisers, and try to reduce the number of things you're trying to remember simultaneously.

Create visual cues. Place items you need to remember in prominent locations. If you need to return a library book, put it by your keys. If you need to take medication, leave it in a place where you'll definitely see it.

Use technology strategically. Location-based reminders on smartphones can prompt you when you arrive at specific places. Medication reminder apps can track doses and send alerts. Smart home devices can provide verbal reminders.

Plan for obstacles. Consider what might interfere with your prospective memory and plan accordingly. If you know you get distracted easily in the supermarket, make a list and check items off as you go.

Final Thoughts

Prospective memory difficulties in ADHD aren't a character flaw or a sign of not caring enough. They're a predictable consequence of how ADHD affects attention, working memory, and executive function. The key is recognising this challenge and building systems that work with your brain rather than expecting it to function like a neurotypical brain.

With the right strategies and support, it's entirely possible to become more reliable at following through on intentions. The goal isn't to have perfect prospective memory—it's to have systems that catch you when your brain doesn't.

Below are some research articles that have investigated prospective memory in people with ADHD:

• Altgassen, M., Scheres, A., & Edel, M.-A. (2019). Prospective memory (partially) mediates the link between ADHD symptoms and procrastination. ADHD Attention Deficit and Hyperactivity Disorders, 11(1), 59–71. Read the article

• Altgassen, M., Kretschmer, A., & Kliegel, M. (2014). Task dissociation in prospective memory performance in individuals with ADHD. Journal of Attention Disorders, 18(7), 617–624. Read the article

• Fuermaier, A. B. M., Tucha, L., Koerts, J., Aschenbrenner, S., Westermann, C., Weisbrod, M., … Tucha, O. (2013). Complex prospective memory in adults with attention deficit hyperactivity disorder. PLoS ONE, 8(3), e58338. Read the article