Strength training helped women who were already showing signs of memory loss, while aerobic exercise did not.

"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."

"It could be that resistance-training requires more learning and monitoring by its very nature," she said. "If you're lifting weights you have to monitor your sets, your reps, you use weight machines and you have to adjust the seat, etc. But with walking it's much more natural for most, so there's less cognitive involvement. But at this point we don't have a clear idea of what's going on at the mechanistic level."

Hmmm. Strength is good for your brain because you gotta keep track of reps and sets?