Alzheimer's Association International Conference (AAIC) 2012. Abstracts F1-03-01, FI-03-02, P1-109, and P1-121. All presented July 15, 2012.
From Medscape Medical News > Psychiatry
Weight Training, Walking Improve Cognition in the Elderly
Never Too Late to Exercise, Researchers Say
Authors and Disclosures
July 15, 2012 (Vancouver, British Columbia) — Physical activity, including resistance training and walking, can increase cognitive functioning in various types of elderly adults, including those diagnosed with mild cognitive impairment (MCI), according to 4 new randomized trials presented at the Alzheimer's Association International Conference (AAIC) 2012.
In the first study, which included elderly women with MCI, those randomly assigned to undergo resistance training/weight lifting sessions for 6 months had significant improvements in attention, conflict resolution, and associative memory scores. They also showed functional improvements in memory brain regions compared with their peers who underwent balance and tone (BT) exercises.
In addition, the women randomly assigned to undergo aerobic training/walking programs showed significantly more improved verbal memory scores and improved physiological functioning than did the women in the BT group.
"MCI is a critical window of opportunity in which we may be able to intervene before the onset of dementia," lead author Lindsay Nagamatsu, a doctoral candidate from the University of British Columbia, Vancouver, Canada, said during her presentation to attendees.
A second study showed that elderly women who were considered "higher functioning" at baseline had higher improvement and maintenance scores on cognitive tests after undergoing resistance training than those who received BT training."Both resistance training and aerobic training have benefits and improve different types of memory. But perhaps a higher dose of aerobic training is required to impact executive functioning and functional plasticity," Nagamatsu told Medscape Medical News following her presentation.
The third study showed that both men and women with amnestic MCI demonstrated significant improvements in language scores after completing a combination exercise program vs a health education program. And study 4 showed that moderate walking by older people without dementia actually increased growth in memory brain regions as well as increased levels of brain-derived neurotrophic factor (BDNF)
"We've been convinced for a number of years that there is a positive relationship between increased physical activity and cognitive function. And the strength of that data continues to increase," William Thies, PhD, chief medical and scientific officer of the Alzheimer's Association, told Medscape Medical News.
Resistance Training Benefits"I'm really happy to see resistance training turning up in the cognitive literature. Like with all of the exercise data, it makes it perfectly clear that physical activity is good for you in many ways — and almost certainly is good for your cognitive function," said Dr. Thies, who was not involved with any of the studies.
Nagamatsu and colleagues enrolled 86 women between the ages of 70 and 80 years (mean age, 74.9 years) with probable MCI into the Exercise for Cognition and Everyday Living (otherwise known as EXCEL) study. The participants were randomly assigned to receive twice-weekly sessions of either resistance training (n = 28), aerobic training (n = 30), or BT training (n = 28) for 24 weeks.
Resistance training was aimed at improving muscle strength and consisted of the use of free weights and a Keiser Pressurized Air System. Aerobic training was aimed at improving cardiovascular health and included an outdoor walking program. The BT group (control group) underwent sessions that included stretching, relaxation, and range of motion exercises.
"Looking at resistance training was important because it reaches a larger proportion of the population. Some seniors aren't able to get up and go outside for a run, or they have mobility issues. But they might be able to lift some free weights in their living room," said Nagamatsu.
The primary outcome measure was selective attention and conflict resolution, as assessed by a Stroop word test. Secondary measures included verbal memory, as assessed with Rey's Auditory Verbal Learning Test (RAVLT); associative memory; and functional magnetic resonance imaging (fMRI) scans to assess functional plasticity.
Results showed that the women who underwent resistance training had significantly higher scores on the Stroop test compared with those who underwent BT training (17% vs 2.4% improvement, respectively; P = .04). Compared with the BT group, the aerobic training group did not show significantly improved Stroop scores.
Associative memory scores were also only significantly better in those undergoing resistance training (P < .03).
However, RAVLT memory scores were significantly higher in the aerobic training group vs the BT group. These women also had significant improvements in balance and in cardiovascular capacity.
The fMRIs showed no significant between-group differences in activation for item memory, but the resistance training group showed increased activation in 3 brain regions during associative memory tasks: the right lingual gyrus, the right frontal pole, and the occipital fusiform gyrus.
"Both exercise groups improved their memory scores, but on different types of memory. More research is needed to determine their differential effects," said Nagamatsu.
"Overall, exercise appears to be an effective intervention for delaying the onset of dementia in seniors who are already showing signs of decline. Although it's probably a combination of both types that make for the most effective strategy, really any type of exercise is important for seniors to be doing."
Baseline Status Key
In a second study, lead author Nader Fallah, PhD, also from the University of British Columbia, and colleagues found that higher functioning elderly women randomly assigned to undergo resistance training for 12 months had a higher probability of improving and maintaining cognitive test scores than those randomly assigned to BT training.
Although test scores between the 2 exercise groups did not differ significantly for the lower functioning women, there was an overall higher probability of cognitive decline and lower probability for improved performance on the Stroop test in the full group receiving BT training.
"To our knowledge, this is the first study to demonstrate that an individual's baseline self-regulatory capacity impacts the amount of cognitive benefit the person will reap from targeted exercise training," said Dr. Fallah in a release.
"We demonstrated that the probability of improving selective attention and conflict resolution in older adults is most evident among those with higher baseline cognitive status — which is different from the current general opinion," added principal investigator Teresa Liu-Ambrose, PhD, from the University of British Columbia and the Vancouver Coastal Health Research Institute, in the same release.
Linear Decline After 30
The third study was presented by Hiroyuki Shimada, PhD, and colleagues from the National Center for Geriatrics and Gerontology in Obu, Aichi, Japan.
Its results showed that men and women between the ages of 65 and 93 years with memory-related MCI who were randomly assigned to a program consisting of aerobic exercise, muscle strength training, and postural balance retraining (n = 25) for a year showed improved scores on the Wechsler Memory Scale and a "significant interaction effect for letter fluency" vs those who participated only in healthy education programs (n = 25).
"In other words, the ability to use language of the multicomponent exercise group improved significantly," said Dr. Shimada in a release.
The fourth study looked at 120 older adults without dementia who had been sedentary for the previous 6 months. The participants were randomly assigned to undergo either a walking program of moderate intensity or stretching and toning exercises for a year.
MRIs were used to measure the hippocampus at baseline and at the end of the exercise programs. In addition, blood samples were gathered to determine BDNF levels, and cognitive tests were given.
"A decline in cognition is preceded by changes in the brain. And we usually see a linear decline starting at about the age of 30," lead author Kirk Erickson, PhD, from the Department of Psychology at the University of Pittsburgh, Pennsylvania, told meeting attendees.
"We wanted to see if it is possible to develop methods to prevent or even reverse the course of this atrophy."
Results showed that those in the walking group had a 2% increase in their hippocampus compared with a 1.5% decrease in the stretching and toning group.
"What's really striking to me about this pattern is that no other treatment, including pharmaceutical treatments, has been able to show this same kind of effect. Getting out and walking is enough to do something that pharmaceutical treatments haven't done," said Dr. Erickson.
"In addition, higher cardiorespiratory fitness was associated with greater volume of the prefrontal cortex, which mediated the link between fitness and cognitive performance," write the study authors.
Dr. Erickson noted that the overall message is that even moderate exercise has widespread effects on the brain.
"Starting to exercise later in life is not futile. Even those who are sedentary can improve brain function. There is no excuse to say, 'I haven't exercised before in my life, so why should I start now?' "
Dr. Thies called the results "convincing."
"For all of these studies, I think if you're at all concerned about cognitive function in the future, you really ought to figure out a way to build physical activity into your life."
Study 1 was funded by the Pacific Alzheimer's Research Foundation. Study 2 was funded by the Vancouver Foundation and by the Michael Smith Foundation for Health Research. Study 3 was funded by the Japanese Ministry of Health, Labor, and Welfare and by the Japanese Ministry of Education and Culture. Study 4 was funded by the National Institute on Aging. All study authors and Dr. Thies have disclosed no relevant financial relationships.