A study involving 86 older women (aged 70-80) with probable MCI has compared the effectiveness of resistance and aerobic training in improving executive function. The women were randomly allocated either to resistance training, aerobic training, or balance and tone training (control group). The programs all ran twice weekly for six months.

The 60-minute classes involved lifting weights (resistance training), outdoor walking (aerobic training), or stretching, balancing, and relaxation exercises (control).

Executive function was primarily assessed by the Stroop Test (measuring selective attention/conflict resolution), and also by Trail Making Tests (set-shifting) and Verbal Digits Tests (working memory). Associative memory (face-scene pairs) and problem-solving ability (Everyday Problems Test) were also assessed.

The study found that resistance training significantly improved performance on the Stroop Test and also the associative memory task. These improvements were associated with changes in some brain regions. In contrast to previous studies in healthy older adults, aerobic training didn’t produce any significant cognitive improvement, although it did produce significantly better balance and mobility, and cardiovascular capacity, compared to the control.

Interestingly, a previous study from these researchers demonstrated that it took a year of resistance training to achieve such results in cognitively healthy women aged 65-75. This suggests that the benefits may be greater for those at greater risk.

It may be that the greater benefits of resistance training over aerobic training are not be solely due to physical differences in the exercise. The researchers point out that resistance training required more cognitive engagement (“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.”) compared to walking.

Note that impaired associative memory is one of the earliest cognitive functions affected in Alzheimer’s.

It’s also worth noting that exercise compliance was low (55-60%), suggesting that benefits might have been greater if the participants had been more motivated — or found the programs more enjoyable! The failure of aerobic exercise to improve cognition is somewhat surprising, and perhaps it, too, may be attributed to insufficient engagement — in terms of intensity as well as amount.

The researchers have put up a YouTube video of the resistance training exercises used in the study.