They Exercised Three Hours A Week For Four Years. Look What Happened To Their Thinking.

By Paul E. Bendheim, MD — Founder of BrainSavers; board-certified neurologist and Clinical Professor of Neurology, University of Arizona College of Medicine – Phoenix; author of The Brain Training Revolution: A Proven Workout for Healthy Brain Aging

Iuliano E, Fiorilli G, Angiolillo A, et al. "Physical exercise for prevention of dementia study: a 48-month randomized controlled trial." Frontiers in Aging, August 10, 2026. The full study is free to read.

Most studies of exercise and the brain run twelve weeks. Some stretch to six months. A year is considered long. I have spent years telling people that protecting a brain is a decades-long project, only to watch the science measure it in weeks. A team in Italy just published a trial that ran for four years. This is a study I have been waiting for.

What They Actually Did

They enrolled 882 adults living in their own homes and communities. Everyone was 50 or older; the average age was 64. Each was randomly assigned to one of two groups, and 674 finished with enough data to analyze.

One group exercised: one hour, three times a week, in supervised groups of ten to sixteen. Every session had the same four parts — ten minutes of warm-up, fifteen to twenty minutes of cardio on a bike or treadmill, twenty to twenty-five minutes of strength work with body weight and dumbbells, and ten minutes of stretching. Effort started light and built up over time.

They did this for forty-eight months.

The other group was asked to carry on exactly as they had been — their usual sedentary or lightly active lives. That is the honest, real-world comparison, and it is what makes the result worth your attention. Everyone was also sorted at the start by how they were doing: healthy, worried about memory but testing normally, or already diagnosed with mild cognitive impairment.

What They Found

The exercisers held steady. The others slipped. The main measure was a thirty-point screening test of overall thinking. Among the healthy participants, the exercise group went from 29.4 to 29.2 across four years — essentially unchanged. The comparison group went from 29.4 to 27.5. That is nearly two full points lost -- a statistically significant result.

Memory did not just hold — it improved. On a word-list test, healthy exercisers recalled about 42 words at the start and about 47 four years later. Their comparison group barely moved. Reasoning and attention scores followed the same pattern.

The mild cognitive impairment group could not be analyzed. Only 93 people fell into that category — too few to conclude anything from. Patients dropping out of clinical trial is not uncommon. The complexities and burdens of life happen to everyone.

What This Study Does Not Say

The trial is named for the prevention of dementia. It did not count dementia diagnoses. It measured performance on thinking and memory tests, which is a different and more modest thing. And the healthy participants started above 29 out of 30 — close to the ceiling of the test, which the authors flag themselves.

So this is not proof that exercise prevents Alzheimer's disease. What it is: four years of evidence that an ordinary, structured exercise program kept measurable thinking ability from sliding in people whose peers slid.

The Really Good News

Look again at the average age. Sixty-four. Not eighty-four. These are the people I have long called the worried well — old enough to be concerned, young enough to do a great deal about it. And what they did was not exotic. Three hours a week. A warm-up, some cardio, some dumbbells, a stretch. That is available at nearly every community center and gym in America.

The earlier you start, the greater the benefit. That has always been true. Now there is a longer measuring stick to say it with.

A Note For BrainSavers Instructors

Participants often ask how long it takes before this "works." This study gives you a genuinely useful answer: the two groups looked identical on day one and separated over years. Frame attendance as the deposit, not the payoff.

For BrainSavers Participants

If you have been showing up week after week and quietly wondering whether it is doing anything, this is the closest thing to an answer research can currently offer you. The people in this trial who kept moving kept their scores. The people who did not, did not.

And if you have caught yourself worrying — a name that would not come, a reason for walking into the kitchen that vanished — go back and read the second finding. Those people were in this study on purpose. They did as well as everybody else.

One more thing, and I do not get to say it often: this paper is open access. You can read every word of it yourself, free, no subscription and no library card — right here. The tables are worth a look even if you skip the statistics.

I have said for years that you are not simply a passenger on the journey of your own brain aging. Four years ago, several hundred people in Italy started showing up three times a week. The difference between them and everybody else is now printed in a journal.

This article is for general educational purposes and is not medical advice. Talk with your own healthcare provider before making changes to your health, exercise, or medication routine.