Exercising During Adolescence Helps Reduce Risk Of Brain Tumor In Adulthood

Xinhua News Agency

October 6, 2009

LOS ANGELES -- Physical activity in adolescence is associated with a lower risk of developing brain tumors in adulthood, a new study suggests.

Exercising later in life, however, didn't seem to matter, according to the study published by HealthDay News on Tuesday.

The study also found that avoiding obesity during the teen years may reduce the risk of developing the cancerous brain tumors called gliomas, said the study by researchers at the U.S. National Cancer Institute (USNCI).

In the study, the researchers examined data on nearly 500,000 men and women aged 50 to 71. The study included questionnaires on height and weight at various points during their lives.

Those who'd reported doing substantial amounts of light, moderate and vigorous exercise between the ages 15 and 18 were 36 percent less likely to develop glioma than those who were sedentary. Activities included walking, aerobics, biking, swimming, running, heavy housework or gardening.

The researchers also found that those who were obese during their teen years had a three to four times greater risk of developing glioma than those of a normal weight. Because only 11 people who developed glioma were also obese as teenagers, researchers said the finding needed to be replicated.

Gliomas are the most common type of brain and central nervous system cancers, accounting for 80 percent of cases, according to background information in the study. Gliomas cause 13,000 deaths in the United States each year.

Though little is known about why people develop the tumors or who is at risk, previous research has hinted that "early life exposures" may increase the risk of developing the cancer in adulthood, said study author Steven C. Moore, a research fellow in the Nutritional Epidemiology Branch of USNCI.

Studies have shown that people who are left-handed, for example, are at higher risk of the disease.

"The BMI (body mass index) finding is very interesting but it's hard to know what to make of it," Moore said.

"It's also hard to say if it's a causal relationship or not. It could be that obesity increases the risk of brain cancer, or if could be that some underlying condition increases both the risk of obesity and brain cancer."

Neither weight nor exercise affected glioma risk beyond the teen years, the study found.

Copyright 2009 XINHUA NEWS AGENCY