If you want to keep your brain healthy as you age, exercise your body. That, in essence, is the conclusion of several clinical trials, the results of which were reported at the Alzheimer's Association International Conference in Vancouver, British Columbia, last month.
The most ambitious study, of 120 sedentary senior citizens, was conducted at the University of Pittsburgh. Walking for exercise slows the memory loss associated with Alzheimer's, report researchers headed by psychology professor Kirk Erickson said.
One group of seniors in the study walked for 30 to 45 minutes three days a week. The other stretched and toned.
After a year, the walkers increased the size of their hippocampus, the region of the brain associated with memory, by 2 percent, as measured with MRIs. Most Alzheimer's patients suffer significant shrinking of the hippocampus.
The researchers also found growth in the prefrontal cortex, the region of the brain associated with decision making and related activities that psychologists call executive function. The more fit the patient, the larger the growth in the prefrontal cortex.
"I would say this is pretty dramatic," Erickson said. "This is only after one year of exercise and moderate intensity at that."
Though it's clear moderate exercise can reduce the risk of cognitive impairment in older adults, little is known about why exercise is good for brain health, or, what, exactly, is the relationship between a larger hippocampus and better memory, he said.
In a six-month study of women ages 70 to 80, researchers at the University of British Columbia in Vancouver found that walking and resistance training (lifting weights) significantly improved performance on the Stroop Test, which measures a person's ability to sustain attention with and without interference. It's commonly used to measure the brain's vitality and flexibility. Only the weightlifters had positive changes in the brain regions associated with memory.
"Twice-weekly resistance training is a promising strategy to alter the trajectory of cognitive decline in seniors with MCI (mild cognitive impairment)," said Teresa Liu-Ambrose, supervisor of the graduate students who conducted the study.
A Japanese study over a year of 47 seniors ages 65 to 93 found that those who exercised for 90 minutes a day improved significantly their ability to use language.
"These latest studies show that resistance training is emerging as particularly valuable for older adults," said William Thies, chief medical and scientific officer for the Alzheimer's Association.