The brain-training approach is based in part on the research of neuroscientist Dr. Ryuta Kawashima of Tohoku University, whose work examined what happens in the brain while people perform different cognitive activities.

Kawashima's research found that even very simple arithmetic—single-digit addition, subtraction, and multiplication—engages frontal brain regions associated with higher-order cognitive functioning.

Importantly, the concept is not that difficult mathematics is required. The exercises used in this research are intentionally simple. The goal is to engage cognitive systems efficiently through repeated mental processing rather than teach advanced mathematics.

The strongest scientifically defensible summary is:

Rapid simple arithmetic engages frontal/executive brain networks, and randomized controlled trials using this type of cognitive training have found improvements that transfer beyond arithmetic to executive function, processing speed, and—in some studies—working memory.

There is also substantial independent neuroscience research showing that executive functions and prefrontal networks are involved in many important aspects of everyday functioning, including planning, inhibition, working memory, cognitive flexibility, self-regulation, emotional regulation, and aspects of social cognition.

Kawashima and colleagues used functional MRI (fMRI) to observe brain activity while children and adults performed very simple arithmetic: single-digit addition, subtraction, and multiplication.

The researchers observed activation of frontal regions during these tasks, including the left middle frontal cortex. Adults also demonstrated right frontal activation during addition and multiplication.

This provides direct neuroimaging evidence that even simple arithmetic recruits frontal brain systems rather than merely functioning as a rote academic exercise.

The most important evidence for this approach is not simply that the brain becomes active while doing arithmetic. The more significant question is whether repeated training produces improvements in other cognitive abilities.

Kawashima's group developed an approach known as "Learning Therapy," involving two deliberately simple activities:

• Reading aloud
• Performing simple arithmetic calculations

In a randomized controlled trial involving healthy older adults, participants performed these activities five days per week for six months.

After training, participants demonstrated improvements in measures of executive function and processing speed.

This is important because those were not simply measures of arithmetic ability. It suggests a transfer effect: repeatedly exercising cognitive systems through simple tasks may improve other functions that depend upon those systems.

A later research protocol reviewing the evidence described the proposed mechanism this way: stimulation of prefrontal systems through these tasks may contribute to positive transfer to other cognitive functions.

Another randomized controlled trial tested Kawashima's Brain Age cognitive-training program in older adults.

After only four weeks, researchers found transfer effects to:

• Executive function
• Processing speed

The participants did not simply become better at the exercises they practiced. Improvements appeared on separate measures of cognitive abilities.

The researchers concluded that short-term brain training could improve executive functions and processing speed in older adults, while appropriately noting that larger studies and research into long-term real-world effects were still needed.

Researchers subsequently conducted a randomized controlled trial in healthy young adults.

Again, the benefits extended beyond performance on the trained tasks.

The brain-training group demonstrated improvements in:

• Executive functions
• Working memory
• Processing speed

This strengthens the argument that the effect is not simply an artifact of cognitive decline in elderly participants.

Executive function is not one isolated skill.

It is an umbrella term encompassing cognitive abilities that allow people to control and direct their thoughts and behavior, including:

• Working memory
• Inhibitory control
• Cognitive flexibility
• Planning
• Decision-making
• Goal-directed behavior
• Attention control
• Processing information efficiently

These abilities are heavily dependent upon networks involving the prefrontal cortex.

Therefore, the potential significance of this type of training extends beyond becoming faster at arithmetic.

The hypothesis is that simple, rapidly performed cognitive exercises repeatedly recruit executive-control systems—and research suggests that at least some benefits can transfer to other executive abilities.

Dr. Kawashima has popularized the idea that simple calculations performed rapidly are especially effective for activating the brain.

An important caveat — It is not scientifically rigorous to say:

The published research supports the effectiveness of simple arithmetic for engaging frontal/executive systems, but it does not establish that arithmetic is superior to every other possible cognitive activity.

However, a strong and defensible statement would be:

Likewise, we should not claim:

That has not been directly demonstrated. What the evidence does allow us to say is:

The exercises may look surprisingly easy, but that is intentional.

Research led by neuroscientist Dr. Ryuta Kawashima has shown through brain imaging that even simple arithmetic engages frontal brain regions involved in higher-order cognitive processing. Randomized controlled trials of cognitive-training programs based on these principles have subsequently demonstrated improvements that extend beyond arithmetic—including executive function, processing speed and working memory.

That matters because executive function helps us do far more than solve math problems. Executive systems help us plan, control impulses, hold information in mind, shift perspectives and regulate behavior.

Independent research has even found a significant relationship between executive function and empathy, particularly cognitive empathy—the ability to understand another person's perspective.

The goal, therefore, isn't to teach people more math.

The math is the exercise. The brain is what we're training.