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Weight Training May Slow Cognitive Decline

Renee DespresFriday, June 15, 2012 - 20:38

Weight lifting and other forms of resistance training may help older women with early signs of cognitive decline, such as memory loss, slow that decline and perhaps stave off dementia. These results are based on a small proof-of-concept study reported April 26, 2012 in the journal Archives of Internal Medicine.

The study was conducted by a research team led by Teresa Liu-Ambrose of the Centre for Hip Health and Mobility at Vancouver Coastal Health  Other investigators were from the University of British Columbia.

The findings, said Liu-Ambrose in a press release, suggest that “that implementing a seniors' exercise program, specifically one using resistance training, can alter the trajectory of decline.”

About Cognitive Decline

Cognitive decline is a global public health problem. About 35.6 million people worldwide were living with dementia in 2010, according to Alzheimer’s Disease International. That number is expected to double every 20 years, reaching 115.4 million in the year 2050.

Often the first indication that someone might develop dementia is a condition called mild cognitive impairment (MCI). A person with MCI has problems with language, memory, reasoning, problem solving, attention, or decision making or other mental functions. These mental functions, or cognitive processes, are referred to as “executive functions.” In a person with MCI, problems with executive functions show up on tests and are noticeable to others close to the person, but they do not interfere with daily life.

MCI is considered an early warning sign of dementia. About 50 percent of people with MCI will go on to develop Alzheimer’s disease or other types of dementia.  Declines in three specific executive functions  strongly predict that a person with mild cognitive impairment will eventually develop dementia: selective attention and conflict resolution functions, as well as associative memory.

Cognitive Decline and Exercise

Prior research has suggested that there may be a link between exercise and improved brain function. However, results have varied widely, suggesting that much more research needs to be done to understand any relationship between exercise and cognition.

In addition, most studies of mental function and exercise have focused on aerobic exercise. Aerobic exercise is the kind of exercise that gets your heart rate elevated for a sustained time – for instance, walking, biking, swimming, or running.  But Liu-Ambrose’s team set out to assess the effects of resistance training in comparison to aerobic exercise on reasoning and decision-making abilities. They tested three types of exercise: resistance training (for example, weight lifting), aerobic exercise, and balance and toning training.

What the Researchers Did

For the study, which they dubbed “The study, dubbed EXCEL (EXercise for Cognition and Everyday Living), Liu-Ambrose’s team recruited women 70 to 80 years of age. All of the women lived in the community (that is, in their own or family members homes; not in assisted-living or other facilities).

The researchers assessed the women’s cognitive status using the Montreal Cognitive Assessment test and interviews. Then they selected women whose scores on the assessment test suggested they had “probable mild cognitive impairment” (MCI).

After identifying 86 women who fit their criteria, the investigators divided the participants into three groups, each consisting of about 30 women. Each group exercised twice a week for 60 minute in classes led by certified fitness instructors. Women in the first group performed resistance training (weight lifting) exercises, while those in the second group engaged in aerobic exercise. A third control group performed balance and toning exercises. The study lasted for six months.

The researchers used the Stroop test, which measures executive functioning, including problem-solving, attention, and decision making, to assess the women’s cognitive status at the beginning and at the end of the study, They also used functional magnetic resonance imaging (fMRI) to get images of 22 of the women’s brains.

Results

Of the 86 women who began the trial, 77 completed it. Women in the resistance training group scored significantly better on the Stroop test and on one memory task (associative memory) than did women in the control group. In the resistance group, blood flow increased to the prefrontal area of the brain – the area that controls most executive functions.

Women in the aerobic training group benefited physically from the exercise. They had better balance, mobility, and cardiovascular capacity than the control group. But there were no difference in their cognitive performance.

The researchers did not find any other differences in results between the three groups.

Participants in the aerobic training group were most likely to drop out of the study. One woman experiences shortness of breath, and four women fell during the study.

"There is much debate as to whether cognitive function can be improved once there is noticeable impairment," said Liu-Ambrose. "What our results show is that resistance training can indeed improve both your cognitive performance and your brain function. What is key is that the training will improve two processes that are highly sensitive to the effects of aging and neurodegeneration – executive  function and associative memory – functions which are often impaired in early stages of Alzheimer's disease."

Limitations

This is a solid study with interesting results. However, the study does not show that resistance training can prevent dementia in general or Alzheimer’s disease in particular. It does suggest that resistance training may be helpful in slowing the pace of cognitive decline in older women with MCI, and that research into this area is needed.

There were several limitations to the study:

  • The study was extremely small, with only 30 or fewer participants in each group.
  • The study design. As a “proof-of-concept” study, the study only yielded preliminary results that suggest the effect of resistance training on cognitive decline is a fruitful area to investigate. That’s all the researchers set out to do – they did not attempt to prove that resistance training can prevent dementia.
  • The study only included women ages 70 to 80 years, so the results can’t be generalized to a wider population.
  • The women had not been diagnosed with MCI; they had only been classified by researchers as having “probable” MCI. Without a definitive diagnosis, it’s not clear how many participants really had experienced MCI.
  • Women’s cognitive status was assessed only twice during the study period – at the beginning and at the end. Their performance on the assessment tests could have been altered by many factors. They could have had a bad day, or not have slept well the night before. More frequent testing would have increased the reliability of the data. And it’s not clear how their performance on those tests translated into the way they handled their daily activities.

What the Study Means to You

Although this small study does not definitively show that resistance training can slow cognitive decline, it suggests that it’s more likely helpful than hurtful. And resistance training has multiple proven benefits for physical and emotional health. There are few downsides if resistance training is undertaken safely and carefully.

So should you head to the gym, no matter what your age and cognitive status? You bet (with your doctor’s permission, of course)! If you’re new to weight lifting, pay for a few sessions with a physical trainer, who can help you ensure that you’re using resistance training machines correctly. If the gym isn’t your style, invest in some small free weights, and hire a physical trainer to help you get going.

The following video, created by Liu-Ambrose and her team, offers a fun peek at why and how to get started:

Source

Liu-Ambrose, T., Nagamatsu, L. S., Handy, T. C., Hsu, C. L. , & Voss, M. (2012) Resistance Training Promotes Cognitive and Functional Brain Plasticity in Seniors With Probable Mild Cognitive Impairment. Archives of Internal Medicine, 172(8): 666 DOI: 10.1001/archinternmed.2012.379

http://archinte.ama-assn.org/cgi/content/full/172/8/666