Thickening of the arteries, which can lead to a heart attack, is a condition most people associate with aging. But a new study finds that signs of the problem can be seen in some young children and urges doctors to take preventive action.

The study, presented at a recent conference of the American Heart Association, reviewed the findings of 26 earlier studies and found that some children had a subclinical form of atherosclerosis, as the condition is known.

''The arteries of those kids are thicker,'' said the lead author of the study, Dr. Sanaz Piran, an internal medicine resident at McMaster University in Canada.

The children who exhibited the changes were already at higher risk for heart disease later in life. They were obese, had high blood pressure, diabetes or high cholesterol.

In all, the studies looked at more than 3,600 children, ages 5 to 18. The studies used a variety of noninvasive measures to assess thickening and stiffening of the arteries and blood flow.

The findings, the researchers said, reinforce the need for doctors to treat risk factors in children with the same attention they give to adults. Children in families with a history of high cholesterol, for example, should have their cholesterol checked, they said.