How Do Children with ADHD and Neurofibromatosis Type 1 Learn to Estimate Time?

What you need to know

• Children with ADHD and Neurofibromatosis Type 1 (NF1) both show impairments in time estimation compared to healthy controls.
• ADHD is characterized by fluctuating performance over time, while NF1 shows stable but impaired performance.
• Different brain mechanisms likely underlie the time estimation difficulties in ADHD versus NF1.

Understanding time estimation and its importance

The ability to accurately estimate time intervals is an important cognitive skill that we use in many everyday activities. For example, when cooking, crossing the street, or planning our day, we rely on our internal sense of time passing. This skill develops throughout childhood and can be impaired in certain neurodevelopmental disorders.

In this study, researchers compared time estimation abilities in three groups of children:

1. Children with attention-deficit/hyperactivity disorder (ADHD)
2. Children with neurofibromatosis type 1 (NF1), a genetic disorder that can cause learning difficulties
3. Typically developing children (healthy controls)

The goal was to better understand how time estimation works in the brain and how it may be affected differently in these conditions.

How time estimation was tested

Children completed a computer task where they had to press a button exactly 1.2 seconds after seeing a cue on the screen. They received feedback after each attempt telling them if they were too early, too late, or correct. The task included 300 trials divided into three blocks, allowing researchers to look at how performance changed over time.

The researchers measured:

• Accuracy: How often children responded in the correct time window
• Reaction time: How long it took children to respond on average
• Variability: How consistent children’s responses were

Key findings

Overall performance

Both children with ADHD and those with NF1 performed worse on the time estimation task compared to healthy controls. Specifically:

• Healthy controls gave more correct responses overall
• When making errors, healthy controls’ responses were closer to the correct time window
• Healthy controls showed less variability in their response times

Differences between ADHD and NF1

While both groups showed impairments, there were some key differences:

• Children with ADHD made equal numbers of early and late errors
• Children with NF1 tended to respond too early more often
• The ADHD group’s performance fluctuated more over time
• The NF1 group’s performance remained consistently impaired throughout the task

Learning effects

By looking at how performance changed across the three blocks of trials, the researchers found:

• Healthy controls showed a clear learning curve, with responses getting more accurate over time
• The ADHD group’s performance was unstable, improving then worsening again
• The NF1 group showed no significant changes in performance over time

What this means for understanding brain function

These results suggest that while both ADHD and NF1 affect time estimation abilities, they likely do so through different brain mechanisms.

ADHD and dopamine function

The fluctuating performance seen in ADHD fits with what we know about how the disorder affects the brain chemical dopamine. Dopamine plays an important role in timing and attention. In ADHD, there are alterations in the dopamine system that can lead to:

• A lower “signal-to-noise ratio” in brain activity
• Less stable cognitive performance
• Difficulty maintaining consistent attention

These factors could explain why children with ADHD showed more variable performance on the time estimation task.

NF1 and broader learning impairments

The stable but impaired performance in NF1 suggests a different underlying issue. While NF1 also affects dopamine in the brain, it impacts several other brain chemicals and processes related to learning and memory. The lack of improvement over time in the NF1 group may reflect broader difficulties with learning from feedback and adjusting behavior.

Conclusions

• Time estimation difficulties are present in both ADHD and NF1, but manifest differently.
• In ADHD, unstable performance may relate primarily to dopamine system alterations affecting attention and timing.
• In NF1, consistent impairment may reflect broader learning deficits beyond just timing abilities.
• Understanding these distinctions could help in developing more targeted interventions for cognitive difficulties in each condition.

This research highlights how studying cognitive skills like time estimation across different disorders can provide insights into brain function. It also emphasizes the importance of looking beyond surface-level symptoms to understand the unique challenges faced by children with different neurodevelopmental conditions.