The same diet that doctors recommend for dodging heart disease also may help preserve brain tissue, a new study finds.

Researchers scrutinized diet surveys from more than 4,200 people with an average age of 66 and ranked the quality of their diets on a scale of 0 to 14. A score of 14 was healthiest and included lots of fruits and vegetables, whole grains, nuts, dairy, and fish, but limited sugar. The volunteers provided data on other factors that might affect brain size, such as blood pressure, physical activity, and smoking. They also underwent brain scans to measure their brain size.

After adjusting for the factors unrelated to diet, researchers found that higher diet scores were linked to greater brain volumes. Brains of people with the healthiest diets were about 2 milliliters larger in volume than brains of people who ate fewer healthy foods. Brain volume usually shrinks as people age, and this shrinkage may be connected to problems with thinking and memory.

The findings, which were published online May 16 by the journal Neurology, cannot prove cause and effect, only an association. However, earlier research noted the same trend in people who followed a similar, heart-healthy Mediterranean diet.