Dementia and Alzheimer’s Disease: Exercise is Good – Studies, Not Always

There is significant evidence that exercise is helpful in lowering one’s risk of dementia by regular moderate to vigorous exercise. And every month a plethora of articles appears reporting on positive impact or no impact at all on a variety of factors from diet and supplements to exercise.

A number of studies have indicated that starting and maintaining an exercise program has been helpful. But, we also need to define what may not be helpful. Exercise below a certain aerobic level, may just not count as preventative exercise for dementia and cognitive decline.

And I realize my bias in favor of exercise, so I must admit that some reviews have found the evidence is weak that exercise is helpful in avoiding cognitive decline.

Reported studies need to be subject to evaluation. One can not blindly accept the authors’ interpretation of the results. The results and protocol need to be rationally evaluated in an absence of hype.

I’m not sure that a recent study by Sink et. al. which did not find a positive correlation between activity and cognition was scrutinized thoroughly in the media. Looking closely at this study we find that they used a good number of patients and controls. But we see that the inclusion criteria of being able to cover 400 meters in 15 minutes is not what many would consider to be an aerobic exercise activity. The study was restricted to those over 70. And the data was not gathered using a Fitbit, Pedometer, GPS motion detector or observation. The data was self-reported.

So what do we know as a result of this study:

  • Being able to move at a speed of 1 mile/hour for 30 minutes  (400 meters in 15 minutes) several times a week is not enough exercise to measurably diminish cognitive decline (it may have other benefits though).
  • Data acquisition by self-reporting may not be optimal. An objective measurement should be used in conjunction with a device to do and record these measurements.
  • The life style changes here may have been too little and too late to have an impact.
  • Commencing exercise prior to age 70 may be better than beginning later. If beginning later, results may only be seen if the individual is capable of exercising a moderate level.
  • Media coverage is often limited in interpretation and assessment of the meaning  of a study’s results.

In a predefined subgroup of those aged 80 and over and with worse starting fitness they did find an improvement in “executive function”.

“Despite the lack of overall benefit, our prespecified subgroup analyses of participants aged 80 years or older and those with lower baseline physical performance demonstrated that the physical activity group had better performance on executive function tasks than those in the health education group at 24 months. This finding is important because executive function is the most sensitive cognitive domain to exercise interventions,40 and preserving it is required for independence in instrumental activities of daily living. Future physical activity interventions, particularly in vulnerable older adult groups (eg, ≥80 years of age and those with especially diminished physical functioning levels), may be warranted.”

The authors did consider as the first possible explanation that the exercise level was insufficient to produce changes in the cognitive measures, but this escaped the media blitz. In reading the article, conclusions and discussion, the study was well designed, properly randomized and controlled, used an adequate sample size. The possibilities leading to the observed results were thoroughly discussed. But again, the subtleties were not discussed in the media and the headlines you saw were that exercise was not useful in preventing cognitive decline. As with most studies the media would lead you to believe that the current study overturns all previous thinking and is the only thing to follow.

Bayesian reasoning allows for new information to be added into the mix of the prior thought and research on any topic. That should be done and the meaning of that should be clear to anyone writing about science literature. One study doesn’t usually replace all thinking, it is added to it in that successive approximation of the truth that we reach for through science.

So the same recommendation to exercise, in my mind, holds. It still has the most evidence pointing in its favor. And for those older individuals who are not able to exercise as vigorously, exercise is still likely to have positive impact on mood and other neurological and physical functions not measured in this study.And I’d suggest more education on EBM and study evaluation for those charged with distributing results of medical studies. And please read the study.

References:

Effect of a 24-Month Physical Activity Intervention vs Health Education on Cognitive Outcomes in Sedentary Older Adults Sink, KM et. al. JAMA. 2015;314(8):781-790. doi:10.1001/jama.2015.9617.

Exercise counteracts declining hippocampal function in aging and Alzheimer’s disease. Intlekofer, K, Cotman, C.  NEUROBIOLOGY OF DISEASE · JUNE 2012

Physical activity and cognitive function in individuals over 60 years of age: a systematic review. Clin Interv Aging. 2014 Apr 12;9:661-82. doi: 10.2147/CIA.S55520. eCollection 2014.  Carvalho ARea IMParimon TCusack BJ

Erickson, KI, Barr, LL, Weinstein, AM, Banducci, SE, Akl, SL, Santo, NM, Leckie, RL, Oakley, M, Saxton, J, Aizenstein, HJ, Becker, JT, Lopez, OL. (in press). Measuring physical activity with accelerometry in a community sample with dementia. Journal of the American Geriatic Society.

Weinstein, AM, Voss, MW, Prakash, RS, Chaddock L, Szabo, A, White, SM, Wojcicki, TR, Mailey, E, McAuley, E, Kramer, AF, Erickson, KI. (2012). The association between aerobic fitness and executive function is mediated by prefrontal cortex volume. Brain, Behavior, and Immunity, 26:811-9.

 

Erickson KI, Miller DL, Roecklein KA. (2012). The aging hippocampus: interactions between exercise, depression, and BDNF. Neuroscientist, 18: 82-97.

Okonkwo, O, Schultz,S et. al. Physical activity attenuates age-related biomarker alterations in preclinical AD. Neurology November 4, 2014 vol. 83 no. 19 1753-1760

 Brown, B, Bourgeat, P et. al. Influence of BDNF Val66Met on the relationship between physical activity and brain volumeNeurology. October 7, 2014 vol. 83 no. 15 1345-1352

Addendum:

Abstract of a British J of Sports Medicine editorial (Exercise is medicine, for the body and the brain, 2014):

“Cognitive decline is one of the most pressing healthcare issues of the 21st century. Worldwide, one new case of major cognitive decline (ie, dementia) is detected every 4 s. Given that no effective pharmacological treatment to alter the progress of cognitive decline exists, there is much interest in lifestyle approaches for preventing or treating dementia. Ideally, such strategies should be cost-efficient and widely accessible at a societal level to have the largest benefit for older adults with varying income and functional status levels.

One attractive solution that aligns with the above criteria is exercise. However, despite a large and consistent pool of evidence generated over the past five decades linking exercise to improved cognitive functions in older adults,2 there is a reluctance among academics, healthcare practitioners and the public alike to embrace exercise as a prevention and treatment strategy for cognitive decline. For example, the National Institutes of Health (NIH) consensus statement from 20103 concedes that there appears to be preliminary data to support the efficacy of exercise in improving cognitive function. However, they caution that there is currently no strong evidence to suggest that modifiable lifestyle factors can alter the trajectory of cognitive decline. Adding fuel to the fire are publications such as a 2013 systematic review of randomised controlled trials (RCTs) (prior to 31 October 2011) reporting ‘weak’ evidence for the effects of exercise on cognition.4 We must highlight that the search strategy used in that systematic review failed to capture many pertinent papers providing evidence from RCTs that exercise promotes cognitive and brain plasticity not only in healthy older adults but also in those with cognitive impairment. Furthermore, there are a number of animal studies that provide insight into the molecular and cellular mechanisms by which exercise promotes neuroplasticity.”

Let’s Get Physical – Olivia Newton John

Evolution, Tolerance, Humaness and Humaneness

As our brain expanded in evolution, we became more and more adaptable. Social structure became more complex, cultural and symbolic phenomena began and refined communication became possible.

Contemplation We developed many types of adaptability: physical, spiritual, cultural and emotional adaptability are among the hallmarks of human evolution. To say that we have evolved to run in one way, and that way must be that we should always land on our forefoot in shoes dictated by any authority is absurd. But the discussion that has taken place in the past few years demonstrates the impact of culture and society on thought and how memes are generated and circulate in traditional and new media.

To say that evolution has mandated that we are designed to wear no shoes or minimal shoes would have precluded our explorations of much of our own planet, let alone our exploration of the moon’s surface. And the movie Gravity just wouldn’t look right with Sandra Bullock wearing a white suit with no shoes while floating around in space.

Have our minds evolved faster than our bodies? Does peer pressure play a major role in our social development? Are we justified in wearing shoes in hostile environments or during particular sports activity? Or should we all take feet as a special evolutionary case in that they are meant to be set free from the encumbrance of all shoes?

Do some intelligent people cherry pick literature for one reason or another and are they knowingly intellectually dishonest? It is possible that some may not even be totally aware of what and why they are taking a particular approach on this topic. A recent study reported in Nature demonstrated that social ideas on climate change are influenced at the subconscious level by those around you. The media can have a tremendous impact. The trend in which the new needs to be continuously highlighted (and yes the new is often good, but not everything new is going to work well or last long – or we wouldn’t need to see so many new shoes every year. ) to the point where what has recently been new and highly touted is suddenly set upon and put down.

Should someone not agreeing with our particular choice engender hate, disrespect and a virtual piling on? That seems to perhaps be a hallmark of humanness but not humaneness. Historically and culturally we often seek the similar and the like and avoid or abhor the different. When cultures merge and converge though, some of the differences no longer matter. Often, those outside of the mainstream or lagging behind the trend line are disparaged. Sometimes quite strongly disparaged. It is clear in politics and global affairs that unfortunately this often guides our approach to life and society.

For the runners among us, I’ve emphasized that we are all runners. That is our commonality and what should bond us together. Politics, shoes, feet, none of that really matters and there is room for all kinds of runners among the running community. There are sprinters, milers, marathoners and ultra-marathoners. There are barefoot runners, minimalist shoe runners, runners in structured cushioned shoes, runners in neutral shoes, and runners who run comfortably in motion control shoes ( a few anyway, but not a good choice for most people). We all run or if we are injured or otherwise unable to run, we all think about running. My belief about shoes is that you should run in what is comfortable and works for you. A recent book on evolution and running insists, in spite of an absence of evidence that comfort is a bad indicator of success. However Benno Nigg and others have done research that indicated that comfort was a relatively good predictor of fewer injuries among military recruits. With all of the research that has been done we still have essentially no studies that tell us how to avoid running injuries. One budding guru said on a national television program “throw away your high tech running shoes and you will never have another running injury”. Unfortunately, that was patently false and misleading. There are a number of new studies showing injury trends with different shoes – the first study which comes to mind is one that concluded a recommendation to wear a motion control shoe just based on a low arch foot type does not work well and seems to lead to more injuries than the choice of another shoe type.

George Sheehan said that “we are all an experiment of one.” We do have to discover what works well for us as individuals and follow that path. There is much to read on the Internet that can be helpful, but the correct answer for one individual may be hard to find. Sometimes guidance and the advice of a professional is helpful when one of us becomes injured, or has repeated injuries.

One thing is certain: everything goes better with exercise. We all are built to move. In fact evolution has led us to be in dire need of movement and evolution.

So now that we have arrived at another end of year holiday season, it is a good time for both reflection and movement. Plan your approach to the next year of exercise. Work on tolerance – improve your tolerance to endurance exercise, strength training and speed workouts. Improve your tolerance to your fellow runners and human beings. Work on being humane in addition to being human.That you’ll find is the hardest type of tolerance to develop.

But that animal in us does need exercise even during the holidays. How else will you work off those large meals and party foods and drinks?

Jacquelin Perry, MD (1918-2013) – Pioneer of Gait, Biomechanics and the Treatment of Neurological Disorders

Dr. Jacquelin Perry (1959)Jacquelin Perry, M.D. has just passed away at age 94. She was born on May 31, 1918 and died on March 11, 2013.

Dr. Perry was a key researcher in gait and abnormal gait. She was a pioneer as one of the few female orthopedists in the 1950’s becoming board certified in 1958. It is hard to imagine today, but there were only 10% women in her medical school class, 7 out of 76.  She taught at USC Medical School from 1972 until the late 90’s. She worked at Rancho Los Amigos Medical Center in California for many years and was Chief of Pathokinesiology and later Chief of the Biomechanics and Gait Lab among other positions. More recently the Jacquelin Perry Musculoskeletal Biomechanics Laboratory was dedicated in December, 2008

She is best known for her work on polio patients and her 1992 text Gait Analysis: Normal and Pathological Function” became an instant classic. The Salk vaccine, introduced in the mid-1950’s, effectively ended polio in the Western World fairly quickly. Dr. Perry directed her attention to improving a rehabilitation program for spinal cord injury, work on hemiplegia, and children’s neuromuscular disorders including primary muscular dystrophy, myelodysplasia, and cerebral palsy.

Before beginning her medical studies Dr. Perry studied physical therapy and served as a physical therapist in army hospitals during WWII from 1941-1945. She reported that in addition to trauma patients, she had been exposed to polio patients during this time which spurred her interest.

From an early time in her career she began observational gait analysis and worked to codify her observations. Later video and EMG (electromyography) and forceplate observations were added.

Her clinical observations and descriptions of “loading response” were clear and had implications for many biomechanists. She also well described the terminology which led to an emphasis by some on “sagittal plane biomechanics”:

  • Heel RockerRock and Roll - Jacquelin Perry
  • Ankle Rocker
  • and Forefoot Rocker

She is acknowledged often in the physical therapy community. Dr. Perry has inspired many to research in gait and biomechanics. But all biomechanists know of her work and realize the thanks owed to her for her interests, work, inspiration and research. We often have had a more limited acknowledgment of our forebearers but she is certainly a major one in the realm of biomechanics and gait analysis.

While we now have improved measuring devices (in laboratories and sometimes in clinical offices) and we measure and make observations of moments of force in addition to the things we can see, her work has had tremendous impact and has had much value. As Galileo performed visual observation with his telescope long before we could study pulsars, quasars and black holes, Jacquelin Perry worked well with the instruments she had available. Eyes and a brain were among the instruments she often put to good use and was the starting point for much research and treatment. Her life is an inspiration to innovation, passion, dedication, persistence and endurance.

Running & Being and Running & Dying (repost 2007)

George Sheehan‘s book “Running & Being” is one that every dedicated runner should read. George, a cardiologist, and one of the early, great running philosophers and gurus has been an inspiration to all old school runners.

Many years back, some people, Jim Fixx included, thought that running marathons would give an immunity to fatal heart disease. While running is certainly excellent for cardiovascular health, this has been found to not be so. The most recent studies seem to demonstrate that long distance running reduces your overall risk from dying from cardiovascular disease but that during running itself your risk is higher than while at rest. I still believe that this is a reason to run and not to avoid running. The overall benefit to reduced risk of cardiovascular disease, high blood pressure, depression, body weight, and many more benefits clearly and strongly outweigh the statistically somewhat increased risk of exercising.

It is important though to note and keep track of your own personal risks. Be aware of your lipid profile, your total cholesterol, your HDLs, LDLs, Triglycerides, and what you must to do make it as good as can be done for you. Be aware of your personal and family history of cardiovascular illness. Have your blood pressure checked, and as you get older have it checked more often. High blood pressure is a serious and by many an underrated, and undetected but major contributor to severe cardiovascular illness. Do not underestimate it or think you may be immune to it because you did not have it for the first 25, 35 or 40 years of your life.

Jim Fixx, author of one of the early and earth shaking popular books on running, died from heart disease while running. Today, Ryan Shay, a promising American runner died in the U.S. Olympic Marathon trials. At this time the cause of death has not been established. It was a very sad thing to learn. He is believed to be the first american elite runner to die during a running event. Earlier this year Alberto Salazar had a severe heart attack and was without a self-sustaining heartbeat for more than 5 minutes. Amby Burfoot recently wrote a great article about Alberto’s heart attack in Runner’s World, in which his personal risk factors were discussed. One of his grandfather’s died at 52 from a heart attack and the other at age 70. He reported that his father had had more than one heart attack. If I recall correctly Alberto was being treated for high blood pressure and an abnormal lipid profile. His lab tests and blood pressure were considered fine while under treatment. Serious heart disease ran in his family. This was pointed out as a risk factor that you can not alter. A few weeks ago I came across another article about Alberto Salazar in a section of the New York Times written by John Brant, an author who has written a book on the famous Salazar – Beardsley Boston Marathon race. Salazar related to Amby Burfoot that his doctor recommended an echocardiogram which would not have demonstrated cardiovascular disease. In the New York Times article something jumped out at me. Alberto, according to this article, had had significant neck and back pain that made him go to visit his physician. Normally, he endures pain stoically. His doctor did a resting electrocardiogram and some lab tests and it seemed normal. He was then given an appointment for some weeks later to have stress electrocardiogram.

“…in Indianapolis, Salazar was unable to sleep, had little appetite and felt perpetually tired. Stabs of pain rose from his neck and back, which he attributed to sitting awkwardly on the plane. As soon as he returned to Portland, his primary-care physician prescribed some tests, which were inconclusive, and referred Salazar to a cardiologist. An EKG stress test was scheduled for early July.”

Unfortunately, before he had that he had his near fatal heart attack. Or as some called it a fatal one that he survived. (Since he lived, even though his heart stopped, I do not call it fatal.). This is another extremely important item for runner’s to note. Do not ignore chest pain, neck pain, left side of the jaw pain, upper back pain and any other pain that makes you think something could be wrong. If you have risk factors or if a possible coronary atherosclerosis is suspected, you don’t need your stress test and or thallium blood flow study next month, you need it now. You should have that test as soon as possible. Salazar had serious signs of heart disease that were perhaps taken a tad less seriously and attended to a little slower than they should have been. His test should have been the following week and not the following month. Another, not quite as good a runner, David Letterman, did get tested early, and had a quintuple bypass. Salazar, was lucky to only need a stent. Happily, both have recovered and are running again.

The Runner’s World article by Amby was excellently written and gripping. Alberto is thoroughly quoted within the article. In trying to figure out why there was a difference in how he related his symptoms before his heart attack to the two authors I was at a bit of a loss. In a close reading though, Alberto clearly wanted to emphasize his spirtual beliefs in both, and perhaps even more so in the earlier interview with Amby. He viewed his heart attack as part of God’s master plan for him. I don’t know why he didn’t mention the symptoms he had. I’d suggest if you do hear a bit of knocking at the door in the form of unusual discomfort, pain, fatigue or dizziness you pay attention quickly.

Since most of you runners are doing all that you can to be healthy, let’s make sure you don’t ignore signs that you need just a little help to keep that ticker working. And don’t put off the stress test, if you need it.

Ralph Paffenbarger, M.D. Dies at Age 84 (repost from 2007)

Ralph Paffenbarger, was one of the first epidemiologists to study and provide evidence for the significance of exercise in lowering the risk of cardiovascular mortality (heart disease, etc.). His earliest studies showed that the risk of being sendentary (for example: sitting on your behind and playing computers games in todays parlance) was twice as great as exercising and burning up 2,000+ calories per week.

Ralph himself became a marathoner and ultra-marathoner.

His studies were significant and have had an enormous impact on health and understanding necessary components to living in a healthy manner. Between dietary changes, treatment of lipid and cholesterol abnormalities, blood pressure evaluation, and improvement in exercise routines, heart disease can be significantly reduced. The incidence of heart disease in the United States has decreased incredibly over the past 30 years.

Dr. Paffenbarger’s obituary may be viewed at the New York Times.