Mental benefits of exercise in aging clarified

Computerized brain training games may improve outcomes from prescribed exercise.

Physical activity improves not only the heart and lungs, but the brain as well, providing a triad of benefits: improved cognition, better physiologic functioning and increased brain volume and hints of revved up neuronal growth. Multiple studies presented at the conference reached a similar conclusion: getting active is essential for preserving cognitive health. Exactly how exercise boosts brain function is still a matter of debate.

“In addition to getting the physical benefits of exercise, people are also getting social interaction and mental stimulation,” the director of the Aging Mobility, and Cognitive neuroscience Lab at the University of British Columbia, Vancouver. Group activities, like exercise, can also help unwind the tangle of diminished executive function and social isolation, a damaging pair.

“When executive function begins to deteriorate, people know that they are losing some of their ability to interact, and so they withdraw and become isolated.” The lack of social interaction contributes to the downward slide of cognition. The primary investigator of a randomized controlled trial that examined the benefits of three different exercise regimens, each conducted twice a week for 6 months: and balance and tone training, which served as the comparator group.

The subjects were 86 women aged 70-80 years. They all still lived at home, but had probable mild cognitive impairment (MCI).

The group is an important one because the natural history of Alzheimer’s disease suggest that about half of those who develop MCI will go on to develop Alzheimer’s dementia. All of the programs were progressive, those in the weight program started with the largest weights they could handle with good form, which were increased as soon as the women exceeded the required number of repetitions. The aerobic group increased their walking speed based on heart rate and perceived exertion. The control group loaded their exercises as well, increasing repetitions and stretching as the trial progressed.

After 6 months, the strength training group had improved by 17% over baseline on measures of executive function,  which was significantly better than either of the group. These women also experienced significant gains in associative memory.

Also saw physiologic correlates to the cognitive findings. Functional MRI showed improved blood flow in the brain regions involved with encoding and memorization of nonverbal associations; the right lingual gyrus, the occipital fusiform gyrus, and the right frontal pole.

The aerobic training group improved in balance, mobility and cardiovascular capacity, but did not have the same kind of cognitive or brain physiologic gains, the balance and tone group maintained their cognitive ability without any additional benefit either.

“To stress that seeing a real improvement with resistance training  — not just maintenance like we did in the control group, talking about women who already have some level of  cognitive impairment. The most positive way of looking at this is that the exercise could be a magic bullet. There is evidence now that exercise may not only be preventive but a potential treatment.”

In a separate study, presented evidence of the molecular underpinning of exercise-induced brain volume changes: Physical activity, stimulates the release of molecules that promote neuronal growth.

A cognitive neuroscience researcher at the University of Pittsburgh, described the results of a walking program that involved 120 cognitively healthy, elderly adults. The participants had been sedentary for at least the previous 6 months.

They were randomized either to a 1-year program of moderately intense walking or to a 1-year of stretching and toning group. At baseline and at 1 year colleagues measured brain volume and levels of brain deprived neurotrophic factor (BDNF).

BDNF is a protein that affects neurons in several ways; it supports healthy neuronal function, encourages stem cells to differentiate into neurons, and stimulates dendritic expansion. BDNF is particularly active in regions associated with memory and executive functioning.

At the study’s end, found that those in the walking program had about a 2% increase in the size of the anterior hippocampus, compared with the stretching and toning group. Increases in BDNF positively correlated with the volume change. He also saw increases in the volume of the prefrontal cortex which correlated with increased cardiorespiratory fitness.

Just how to translate these controlled experimental situations into effective, real--life practice isn’t completely clear especially when patients already have difficulty with planning and prioritization. Colleague, also of the University of British Columbia, used his expertise in biostatistics to explore that problem. Using a similar cohort of women, he found that those with higher baseline cognitive function reaped the greatest benefit from resistance training.

Conducted a secondary analysis of a 12-month, randomized, controlled trial of 55 women aged 65-75 years the women were assigned to resistance training or balance and tone training.

This new analysis found that women with lower baseline functioning not only experienced less improvement from exercise, but also responded equally to both resistance training and balance and tone training.

“To our knowledge, this is the first study to demonstrate that an individual’s baseline self-regulatory capacity impacts the amount of cognitive benefits the person will reap from targeted exercise training,” the study sheds valuable light on the concept of personalizing exercise prescriptions.

“This brings us to another dimension to consider,” “when prescribe exercise, most of the time we focus on physical ability: “can the knees take it, what is the cardiovascular state?” but people who have better executive function at baseline can execute this prescription better. They can plan their time, prioritize their activities, and follow through with the commitment.”

Findings suggest that “cognitive priming” might improve outcomes in prescribed exercise. Computerized brain training games are one thing to consider. They’ve been shown to improve memory and executive function to both cognitively healthy and impaired older adults. Just a small improvement in executive function and memory could be enough to get a patient invested in an exercise program. “But for those with more pronounced dementia, it’s really about engaging the caregiver,” “need to give them the tools they need to implement this as part of the daily lives of their loved ones.”