Seventy-seven women completed the program, which included standard verbal and visual memory tests, and decision-making and problem-solving tasks. Almost one-third underwent functional MRI at the start and end of the study to look for brain activity changes.
After 6 months, compared to those in the balance/tone classes, the strength-training group was found to have experienced "significant" cognitive improvement.
The strength-training group also experienced activity changes in three specific parts of the brain's cortex associated with cognitive behavior, the researchers found. These changes were not seen among the balance/tone group.
As for the aerobics group, while significant physical improvements were cited relative to the balance/tone group, this group did not appear to accrue the same mental benefits as the strength-training group.
The findings might even be conservative, the authors said, because many women skipped classes.
The team cautioned that their findings may not necessarily apply to women of a different age group, or to men in general.
Catherine Roe, an assistant professor of neurology at the Washington University School of Medicine in St. Louis, hailed the effort as a "worthwhile avenue of exploration" while also expressing some surprise.
"There is certainly other work that has also suggested that exercise can be beneficial cognitively," she noted. "Participation in physical activity definitely seems to help preserve memory and thinking skills."
On the other hand, Roe said, this study "surprises me, because I can't think of a mechanism off-hand why one (exercise method) would work and not the other."
To that point, Liu-Ambrose said that for now, her team could only hypothesize.
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