by Megan Brooks
May 2, 2012 — Six months of twice-weekly resistance training (RT) improved executive function, associative memory, and regional patterns of functional brain plasticity in a group of older women with probable mild cognitive impairment (MCI).
“We provide novel evidence that RT can benefit multiple domains in those at risk for dementia,” the researchers report.
“We found improvement in both cognitive and brain function with resistance training — not just maintenance — over the 6 months. Thus, our results imply that resistance training can delay the onset of dementia in older adults,” first author Teresa Liu-Ambrose, PhD, PT, from the Aging, Mobility, and Cognitive Neuroscience Laboratory, University of British Columbia, Vancouver, Canada, told Medscape Medical News.
In a previous study reported by Medscape Medical News, she and her colleagues found that 12 months of twice-weekly RT significantly improved executive function in cognitively healthy older women. Their latest study found improvement after only 6 months and in women with MCI. Thus, the benefits of RT on executive function “may be more potent among those at greater risk for dementia,” the researchers say.
“Among individuals with MCI, over half will develop dementia in the next 5 years,” Dr. Liu-Ambrose noted. “Our finding is new and greatly extends our current knowledge about the potential benefit of exercise in reducing the risk of dementia in older adults.”
Their findings were published April 23 in the Archives of Internal Medicine.
The EXCEL Study
The Exercise for Cognition and Everyday Living (EXCEL) study enrolled 86 community-dwelling women aged 70 to 80 years with probable MCI (defined as a score < 26 [of 30] on the Montreal Cognitive Assessment) and subjective memory symptoms. They were randomly allocated to twice-weekly, instructor-led classes (60 minutes each) of RT (28 women), aerobic training (AT; 28 women) or balance and tone training (BAT; 30 women, control group) for 6 months.
For RT, both a Keiser Pressurized Air system and free weights were used. Participants performed 2 sets of 6 to 8 repetitions, and loading was increased when sets were completed with proper form. The AT program involved walking outdoors at 40% of a participant’s age-specific target heart rate and progressed to 70% to 80% of target heart rate. The BAT program comprised stretching, range of motion, balance exercises, and relaxation techniques.
Seventy-seven (89.5%) of the 86 participants completed the trial (26 in the RT group, 24 in the AT group, and 27 in the BAT group). Twenty-two participants were included in a functional magnetic resonance imaging analysis (7 each in the RT and AT groups and 8 in the BAT group).
After 6 months, compared with the BAT group, the RT group showed significantly improved performance on the Stroop test (P = .04), an executive cognitive test of selective attention/conflict resolution, which was the primary outcome. The RT group also performed significantly better on an associative memory task (P = .03).
Compared with BAT, RT also led to functional changes in 3 regions of the cortex — the right lingual (P = .03) and occipital-fusiform (P = .02) gyri and the right frontal pole (P = .03) — during the associative memory task.
The researchers also found a significant positive correlation between change in hemodynamic activity in the right lingual gyrus and change in behavioral associative memory performance (P = .02).
Twice-weekly AT significantly improved general balance (P = .03) and cardiovascular capacity (P = .04) compared with BAT.
Findings “Timely and Relevant”
“This small study provides evidence that weekly resistance and aerobic training programs can improve brain blood flow and in so doing increase performance on memory tests,” Cyrus A. Raji, MD, PhD, University of Pittsburgh Medical Center Mercy Hospital, Pennsylvania, who was not involved in the study, told Medscape Medical News.
“While the study was limited to elderly females, women as a group are at a higher risk for Alzheimer’s, making the findings of the study timely and relevant. Larger studies need to be done looking at combinations of different physical activity regimens across gender and wider age ranges,” Dr. Raji added.
Dr. Liu-Ambrose cautioned that although RT was “more beneficial” than AT in promoting both cognitive and brain function, “more research is needed to refine exercise prescription for optimal benefit.”
Dr. Raji agrees. While this study “seems to suggest that [RT] is more beneficial that [AT], caution must be exercised in interpreting the results because more people dropped out of the [AT] group,” he said.
A study published in 2010 in Archives of Neurology and reported by Medscape Medical News at that time did find that a 6-month high-intensity aerobic exercise program improved cognitive performance on multiple tests of executive function in older adults with MCI.
Differences in both the frequency and intensity of AT regimens between the 2 studies may underlie the differing results, Dr. Liu-Ambrose and colleagues note in their report. In addition, the women in their study were older and had lower baseline Mini-Mental State Examination scores.
The study was supported by the Pacific Alzheimer’s Research Foundation. The authors and Dr. Raji have disclosed no relevant financial relationships.
Arch Intern Med. 2012;172:666-668. Abstract