Pumping iron also pumps up the memory of older women with mild cognitive impairment, researchers reported.

In a randomized, single-blind trial, women who lifted weights had significant improvements in memory tasks after 6 months, compared with women in a control group who worked on balance and stretching, according to Teresa Liu-Ambrose, PhD, of the University of British Columbia in Vancouver, and colleagues.

Women in a third group, who worked on aerobic training, saw their fitness improve but got no cognitive benefit compared with the control group, Liu-Ambrose and colleagues reported in a letter published in the April 23 issue of Archives of Internal Medicine.

Exercise is a “promising strategy” for controlling cognitive decline, the researchers noted. Indeed, both aerobic and resistance training have been shown to improve cognitive performance and functional plasticity in healthy seniors living in the community as well as those with mild cognitive impairment, they noted.

But the comparative efficacy of the two modes of exercise hasn’t been examined in people with mild cognitive impairment. To help fill the gap, they enrolled 86 community-dwelling women ages 70 to 80 with subjective memory complaints and a score lower than 26 out of 30 on the Montreal Cognitive Assessment.

They were randomly allocated to twice-weekly sessions of resistance, aerobic, or balance and tone training. Those in the resistance group used machines and free weights, while those in the aerobic group undertook an outdoor walking program. The balance and tone sessions consisted of stretching, range of motion and balance exercises, and relaxation techniques; the patients in this last group served as controls.

The primary outcome was performance on the Stroop Test, which measures selective attention and conflict resolution, but the researchers also tested other aspects of executive cognitive function, including set shifting and working memory, as well as measuring associative memory and everyday problem-solving ability.

They used functional magnetic resonance imaging on 22 of the participants (7 to 8 from each group) to assess regional patterns of functional brain plasticity during the associative memory tests. The investigators also assessed general balance and mobility and cardiovascular capacity.

Compared with the balance and tone group, they found:

  The resistance training group had significantly improved performance on the Stroop Test and the associative memory task (P=0.04 and P=0.03, respectively).
  During the encoding and recall of associations, those in the resistance training group also had significant functional changes in three cortical regions - the right lingual and occipital-fusiform gyri and the right frontal pole (P=0.03, P=0.02, and P=0.03, respectively).
  They also had a significant positive correlation between change in hemodynamic activity in the right lingual gyrus and change in behavioral associative memory performance (correlation coefficient r=0.51, P=0.02).
  The aerobic training group significantly improved general balance and mobility and cardiovascular capacity (P=0.03 and P=0.04, respectively).

The analysis provides “novel evidence” that resistance training has several benefits in terms of cognition, the researchers argued, at least for older women. They cautioned that the results might not apply to men or to women of other ages.

Primary source: Archives of Internal Medicine
Source reference: Nagamatsu LS, et al “Resistance training promotes cognitive and functional brain plasticity in seniors with probable mild cognitive impairment” Arch Intern Med 2012; 172(8): 666-668.