Simon Says Stop: What a Children’s Game Can Teach Us About Early Huntington’s Disease

Do you remember playing “Simon Says” as a child? It was fun, silly, and surprisingly tricky. You had to listen carefully and only act when you heard “Simon says”. If you moved at the wrong time, you were out. It turns out that Simon Says isn’t just a playground game. It’s also a helpful way to understand what happens in the brains of people with early-stage Huntington’s disease (HD).

A recent study by Dr Marianne Vaugoyeau and her team of researchers from Marseille, France, investigated how HD affects attention and action impulsivity. Action impulsivity refers to the ability to stop ourselves from acting too quickly. This study showed that even before the more visible symptoms of HD appear, it may become harder for people with HD to manage their attentio, but not action impulsivity.

Everyday Life: Simon Says Moments

We’ve all had moments where our mind and body don’t quite sync up. Maybe you’ve started speaking before thinking, forgotten what you were about to say, or found your attention drifting in the middle of a task. It’s frustrating, and very human.

These everyday slips can occur more often and be more disruptive for people with early HD. They might interrupt a conversation even though they know they shouldn’t. Or they might buy an expensive fitness tracker on impulse, thinking it’ll be motivating,  you mostly use it to check the time.

These aren’t just moments of forgetfulness or distraction. They’re part of an invisible struggle in the brain, a tug-of-war between acting impulsively and trying to stay focused.

Why Does This Matter?

Understanding impulsive behaviour and attention issues in people with HD is important for several reasons:

• Early recognition: Subtle changes in attention and impulsivity could help doctors spot HD earlier and plan timely interventions.
• Better support: Families and caregivers might misread impulsive or inattentive behaviour as rudeness or laziness. Knowing it’s part of the condition can help reduce misunderstandings.
• New treatment possibilities: If we can target the brain systems involved in impulsivity and attention, we might improve quality of life, even in the early stages of HD.

The Adult Version of Simon Says

To explore these early changes, Dr Vaugoyeau and her team of researchers invited 20 people with early HDand 20 people without HD to take part in a computer task. 

In this study, ‘early HD’ refers to Stages 2 and 3 of the Huntington’s Disease Integrated Staging System (HD-ISS). For more information on HD-ISS categories, see our article about this system. In Stage 2, people with HD begin to experience symptoms. There may be changes in their movement, mind, and mood symptoms. The individuals affected can often still manage most daily tasks independently. In Stage 3, symptoms are more fully developed and have a bigger impact on daily life, meaning individuals usually need more support for everyday activities.

How to Play: Simon Says for Grown-Ups

The computer task was a bit like a grown-up version of Simon Says, and fittingly, it’s called the Simon task.

Here’s how it worked:

1. A green or red shape appeared on the screen. Participants then pressed a button on either their left or right hand, depending on the shape’s colour. Sounds easy? Not quite.
2. Sometimes the shape appeared on the correct side of the screen (e.g. shape on the left, press the left button). That’s like when Simon actually says what to do. No confusion, just follow the rule.
3. But other times the shape appeared on the opposite side of where you’d expect (e.g. shape on the left but press the right button). That’s similar to Simon being sneaky, your brain might want to follow the shape instead of the rule! 
4. The goal of this game? Ignore where the shape appears and focus only on its colour. It’s a fast-paced way to test how well people can stop, think, and act.

Thumbs on the Trigger (Sort Of)

During the Simon task, researchers placed tiny sensors on participants’ thumbs to measure muscle activity using electromyography (EMG). Sounds fancy, but it’s basically a way to eavesdrop on your muscles. EMG picks up the tiny electrical signals your muscles send out when they’re thinking about moving, sometimes even before you actually do anything. So even if a participant managed to stop themselves from pressing the button, the researchers could tell if their thumb had already whispered, “Let’s go!” This helped them figure out who was acting on impulse and who had better self-control, all by spying on a twitchy thumb!

What Did the Study Find?

People with early HD were able to do the Simon task, but they responded differently compared to those without HD:

1. People with early HD didn’t start moving their thumbs too quickly after the shape appeared on the screen. In other words, they weren’t acting on impulse.
2. Their brains took longer to figure out what to do. However, once they knew what to do, their physical movement was just as quick as people without HD.
3. They struggled to pay attention properly, like missing some of Simon’s instructions or getting distracted halfway through the task. Participant’s scores on attention-based surveys matched these findings.

Final Thoughts: More Than a Game

This study shows that even at the very earliest stages, HD begins to affect the way people respond, focus, and control their actions. But it doesn’t mean people with HD are acting impulsively all the time. Their brains just need more time to process what’s going on, and they may find it harder to stay focused. This research offers a hopeful message because it shows that even in early HD, the brain still retains control over actions and attention. Perhaps future treatments could focus on preserving these abilities, before more symptoms develop. It also gives people with HD and their families a clearer picture of what’s happening, making those frustrating moments feel less confusing.

After all, just like in Simon Says, the rules of attention can get tricky. But with the right tools and support, people with HD may stay in the game longer, and play it on their own terms.

TLDR:

• A “grown-up Simon Says” task helped researchers study attention and impulse control in early Huntington’s disease (HD).
• Electromyography (EMG) sensors detected tiny thumb muscle signals to see when movements were prepared, even if stopped.
• People with early HD showed slower processing and attention difficulties, but not increased impulsivity.
• Early changes in attention can help doctors spot HD sooner and guide better support and treatments in the future.

Learn More

Original research article, “Action impulsivity and attention deficits in patients at an early stage of Huntington disease” (paid access).