By Simon J. Evans, PhD

What does the word ‘fitness’ mean to you? Do you think of a body builder or a marathon runner? Do you think an Olympic swimmer? How about an old person reading a map? Huh? Where’d that last one come from?

A new study published in the January 2009 edition of Hippocampus finds that older adults (59 to 81 years) who were more fit had increased spatial memory compared to less fit adults of the same age. They also had a bigger part of the brain, called the hippocampus, which is involved in learning and memory. The hippocampus is also a part of the brain that is particularly targeted in Alzheimer’s disease. Currently science assumes that when it comes to the hippocampus, bigger is better.

Larger hippocampi (plural form) are also associated with better ability to handle stress. In fact, some studies show that war veterans with a larger hippocampus have less intense post-traumatic stress disorder. This may be because their bigger hippocampi protect them from stress better. It may also be that stress itself, shrinks the hippocampus. In fact, the data suggest that both are probably true.

Having a genetically endowed hippocampus probably puts you at somewhat of an advantage when it comes to handling stress. But learning to manage stress can probably also protect your hippocampus and help you age with a little more cognitive grace.

In this new study, researchers recruited 109 older adults and tested their level of physical fitness using a treadmill, measuring aerobic fitness, heart rate and blood pressure. After that, the participants all had their brains scanned in an MRI machine, allowing researchers to measure the size of their hippocampus.

When they compared the two types of measures, low and behold, increased aerobic fitness correlated with increased hippocampal volume, a bigger hippocampus. But the researchers didn’t stop there. They also tested all the participants on spatial memory tasks.

Using a computer, dots were flashed on the screen and the subjects had to remember where those dots came up, monitoring one, two or three dots at the same time. Again, the older adults with better fitness measures performed better on this test.

The researchers believe that the reason they do better on the tests is because they have bigger hippocampi, and the reason they have bigger hippocampi is because they are more fit.

This all make sense, knowing what we know about how exercise boosts brain function. However, we still have to point out that this is a retrospective study. This means you can’t say for sure that increased fitness caused increased hippocampal size and increased performance on memory tests. There may be other factors.

Still, when you look at this new study in the context of all the other studies showing that exercise is good for the brain, it sure seems to be true. This is one more piece in the mind-body connection puzzle. Every day research comes out making it clearer and clearer that the health of your body influences the health of your brain. So if you want to stay sharp in those older years don’t just rely on crossword puzzles in the daily paper to get you there – unless you’re taking a brisk walk down to the corner store to pick it up.

Reference:
Hippocampus. 2009 Jan 2. [Epub ahead of print]

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By Paul R. Burghardt & Simon J. Evans

In the last article we spoke about the age at which a person develops diabetes increases their risk for different types of dementia. In effect, the longer you can hold-off developing diabetes the less risk you have for developing vascular dementia and Alzheimer’s Disease.

A recent article by De Felice and colleagues in the Proceedings of the National Academy of Sciences speaks to how preventing diabetes or effectively managing the disease can affect brain cells at the microscopic level.

In this study, the researchers were able to show that insulin blocks the protein A-derived diffusible ligand (ADDL). This protein causes all sorts of problems for neurons including withering of the “spines” that make connections with other neurons and redistribution of other neuronal components (receptors) that are critical for the formation of memories.

In a sense, it appears that insulin is helping neurons stick to a microscopic version of the “use it or lose it” principle. When insulin was able to interact (bind to) insulin receptors the ADDL protein was not able to bind to the nerve cells. If you don’t use your insulin receptors, you lose parts of your brain cells (i.e. spines).

One issue that needs to be pointed out regarding this paper is that these studies were carried out in “cell culture.” No, this is not a New-Wave band from the 80’s. Cell culture, in science at lease, refers to a technique used to grow cells in a dish. Once you have cells growing in this very controlled laboratory situation, you can test the effects of different drugs, chemicals, nutrients on various functions of those cells. This is great for learning about how the nuts and bolts of cell biology work, however this is not a “natural” situation for a cell, and it can be difficult to directly use the information gleaned from cell culture experiments in an intact organism (i.e. a walking talking human).

With that cautionary point about cell culture experiments in mind, we’d like to point out that there are studies showing that insulin-sensitizing drugs (drugs that help the body use insulin) can improve memory in diabetics and people with Alzheimer’s Disease. So this is something that people should pay attention to! Not just us nerdy scientists that are fascinated by how things work under a microscope.

The real take-home message for diabetics, relating to the previous blog, is that good management of your diabetes is EXTREMELY important. If insulin has the ability to block these nasty little ADDL proteins from eating the branches of your brain cells, then the better control of your insulin levels should help you fend off these proteins. If you are not diabetic, but have a family history, then take steps to reduce your risk of developing diabetes. This disease occurs over time, so the longer you can avoid it (see the February 17th blog) the less you are likely to accrue.

Now, if you’ve been reading faithfully, you’ll notice Simon focused on the same article in “Control your blood sugar, Improve your memory?” on February 11th, but we wanted to revisit it to tie together with the posted on February 17th, “Diabetes increases risk for developing dementia: what control do you have” to emphasize that no matter if you have ‘normal’ blood glucose control or have diabetes you can help reduce your risk for developing dementia.

Another side-note….although the narrator of the video clip below mentions that insulin does not cross the blood brain barrier (which protects the brain from bad stuff), there is pretty good evidence indicating that insulin actually does cross into the brain.

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By Paul R. Burghardt

A recent report by Xu and colleagues in the journal Diabetes, addresses one of the “modifiable risk-factors” for developing dementia. In other words, it tried to identify those things we do and control on a day-to-day basis that ultimately reduce or increase the likelihood of developing disease. These modifiable risk-factors include things like weight-management, blood pressure control, managing diabetes, and exercise. This study focused on how diabetes can influence the chances that we develop dementia depending upon genetic traits and when in the lifespan a person develops diabetes.

Since diabetes increases the risk of developing Alzheimer’s disease, as well as vascular dementia (yep, unfortunately there are a couple of ways to develop substantial cognitive decline), understanding how genetics and lifestyle choices interact during the development of disease will provide a lot of information that can be used for both prevention and treatment. We already know that avoiding diabetes, or managing diabetes effectively, is of the utmost importance.

To address the issue of how the development of diabetes relates to the risk for dementia, Xu and colleagues utilized the Swedish Twin Registry. This is a national survey in Sweden that tracks health information about twins, which is pretty cool for research purposes. Plus, it’s good to know the Doublemint girls are keeping busy, right?

Their general findings weren’t too surprising: diabetes increases the risk for developing dementia whether it be, vascular dementia or Alzheimer’s disease. However, there were some distinct findings in this study emphasizing that timing is everything.

A particularly interesting finding was that the risk for dementia (vascular or Alzheimer’s disease) increased if a person developed diabetes before they turned 65. By the way, the most common time for Alzheimer’s disease diagnoses is in people 65 years of age or older. Remember, this disease takes a number of years to develop, so what you do now may have a substantial impact on how your brain ages.

This probably occurs by the amount of ‘wear-and-tear’ your brain is able to handle under diabetic conditions, particularly if you are genetically predisposed to developing dementia. The concept of cumulative wear-and-tear has a fancy name, “allostatic load.” This idea is important for all aspects of our health as it accounts for the interactions between our genes and environment in a time-dependent manner. But that is for another post….

In general, this study reiterates a couple of issues. First, it highlights the importance of the mind-body link. Although many people think that diabetes is a problem for blood sugar control, it influences a lot of other organs in our bodies, including our brains. Second, if you have a family history of diabetes the longer you avoid developing the disease the better this will be for your brain (and rest of your body).

Unfortunately in this study the authors weren’t able to look at individual’s ability to control/manage their diabetes. But I’d like to be optimistic and believe that better management of a disease like diabetes would help decrease its negative influence on other aspects of our biology. In line with this, please see our blog post for this Thursday!

Reference:
Diabetes. 2009 Jan;58(1):71-7. Epub 2008 Oct 24.

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By Simon J. Evans, PhD

Remember the ‘monster cereals’? Frankenberry, Booberry and Count Chocula? I liked the little marshmallows in Frankenberry the best, though the chocolate milk left behind by Count Chocula was hard to beat. But can eating these types of breakfast cereals be setting us up for future memory problems?

We’ve learned a lot over the past couple of decades about how the foods we choose to eat as kids and young adults, control our risks for chronic illness as older adults. More recently we are beginning to understand that many chronic diseases are related to each other. Now, a new study published the February 2009 issue of The Proceedings of the National Academy of Sciences (USA), adds a very interesting chapter, linking blood sugar control to memory decline.

Specifically the study examines the role of insulin in countering Alzheimer’s disease progression. But before we get into that, let’s connect a few dots.

We know that high sugar foods, if eaten on a regular basis, increase our risk for insulin resistance and diabetes. What does this mean? When you eat high sugar foods your blood sugar rises quickly and your body brings it back down by releasing insulin. However, if you continue to do this on a regular basis, your body will become less sensitive to its own insulin and require more and more of an insulin release to do the job. This is called insulin resistance and is a step toward diabetes.

In recent years, we have learned that insulin acts in the brain as well. Brain cells rely on this hormone to keep a regular supply of energy so you can think clearly, remember where you parked your car and why you went into the store in the first place. Insulin resistance in the brain may lead to mood and cognitive problems. While this is a young area of research we know that diabetes increases your risk for both depression and Alzheimer’s disease.

The new study gives us some insight into why this might be true. One feature of Alzheimer’s disease is an accumulation ‘tangles’ from a protein called amyloid-beta. It turns out that small pieces of this protein can attack certain cells in your brain that are responsible for making and storing memories. If these attacks get bad enough – boom, Alzheimer’s disease.

What the new study shows us is that insulin helps protect these ‘memory’ cells from attack by amyloid-beta, but only if the cells remain sensitive to insulin. This sheds light on why diabetes puts you at increased risk for Alzheimer’s disease. If you have lost sensitivity to insulin (become insulin resistant) then you may be more susceptible to attack by amyloid-beta proteins and the development of Alzheimer’s disease.

In their study, the researchers were able to ‘help’ insulin out using a diabetic drug that increases insulin sensitivity, and this is promising news for development of therapies to help people going down the Alzheimer’s road. But are there other ways to increase our insulin sensitivity. The answer is emphatically, yes!

First of all, exercise is known to boost insulin sensitivity, even if you are already diabetic. Getting your muscles working helps them regain their sensitivity to insulin and do a better job of maintaining blood sugar. Second, eating a low-glycemic diet, with high fiber and low sugar, help regulate blood sugar and boost insulin sensitivity. Third, sleep is an emerging factor in improving insulin sensitivity and blood sugar control.

Again, this returns to the fundamentals. Exercise more, eat better and get enough sleep. Understanding all the cool neuroscience on why these things help is great, and hopefully provides you with a little extra motivation. Sometimes connecting a behavior to a real change that you can put your finger on can give you that extra sticking power, which is why we write these summaries. But the decision is yours. You know what to do, now can you do what you know?

Reference:
Proceedings of the National Academy of Sciences (USA). 2009, 106(6):1971-1976.

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By Simon J Evans, PhD

Why is it that some people freak out when presented with challenges in their life while others handle them calmly and responsively? This is a question that psychologists have pursued for years and it essentially boils down to your coping skills. Now, a new study suggests that these skills may also help protect you from developing dementia in your later years.

We all freak out occasionally, but we’re talking about stress so consuming that you become temporarily unable to deal with life. Some people experience this kind of stress on an almost daily basis, while others rarely let life push them out of control. Most of us fall somewhere in between.

Related to this personality trait, researchers in Sweden followed 506 older people (average age of 83) for several years and looked for things that predicted who would develop dementia over the course of the study. They honed in on a couple of things that were important when considered together. First, was their level of social activity and second, their level of neuroticism, which in this case can be thought of as coping skills to reduce stress.

The new study found that those folks who were less socially active and had poor coping skills had twice the risk of developing dementia. In this small cohort, either social isolation or poor coping skills was not enough to increase risk, but the double whammy was significant. However, prior larger studies have found negative effects of each of these independently.

Previous research has shown that social isolation puts folks at higher risk for dementia and that poor coping skills increase risk for depression. Importantly, depression and dementia seem to frequently go hand in hand in older individuals. So regardless of which is worse or how social activity and coping skills combine, it’s likely that having social support and good coping skills is good for your brain in multiple ways.

The cool thing about these is that you can do something about them. Researchers call these types of factors ‘modifiable’ risk factors, meaning you have control over them. You can increase your level of social activity and improve your coping skills through a variety of techniques. If you feel isolated, unless you live in the middle of nowhere with no transportation, you can increase your level of social activity just by getting involved with your community. Over time you will make more friends and increase your social circles. As for coping skills, there are hundreds of books, classes and websites that can help you learn to handle stress more effectively.

The four cornerstones of brain fitness that we discuss in detail in our book, BrainFit for Life, will also help you develop coping skills. Specific nutrients, physical and mental activities and getting optimal sleep all control brain circuits that regulate stress and your ability to deal with it. The more you focus on these fundamentals, the more you will be surprised by the power that they have over your daily experiences and the more you will get out of life with a fit brain.

Reference:
Neurology (2009) 72, 253-259.

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By Simon J. Evans, PhD

The head bone connected to the neck bone, The neck bone connected to the back bone, The back bone connected to the thigh bone . . . Dem bones, dem bones gonna walk aroun’, Dem bones, dem bones, gonna walk aroun’. . . remember that song? It’s a basic principle. Your body systems are all connected up. So it should be no surprise that the health of your brain is connected to the health of your body and a new study revealed just how much.

We’ve known for some time that fit people feel better, and more recently discovered that they may also think better. Canadian researchers took this to the test by looking at how the physical fitness level 50 – 90 year old women predicted their cognitive abilities. Their research will be published in the March 2009 edition of the journal, Neurobiology of Aging.

The research team recruited 42 healthy post-menopausal women who were free of chronic illness and medication. They then evaluated their level of physical fitness using a standard exercise test and compared fitness levels to cerebral blood flow (blood supply to the brain) and a battery of cognitive performance tests.

Not surprisingly, women who reported getting regular exercise were more fit than women who were sedentary. But let’s explore for a minute what fitness actually means to these women. First, fitness significantly predicted the cerbrovascular health of these women, which is a fancy way to say that fit women had a better blood supply to their brains.

What does that mean? Basically, it means their brains can perform better and they proved it by doing better on all kinds of cognitive tests, including cognitive speed, perception, verbal ability and executive function. Even if you don’t know what all of these test measure, understand that the physically active women out-performed the sedentary women on every cognitive test the researchers through at them.

We all know that exercise helps our heart and arteries work better. For some people, that is motivation enough. However, only about 1-3 adults get any regular exercise so maybe we need a bigger motivator. Understanding that physical fitness will also make your brain work better might be the driver that many people need. While nobody wants diabetes and heart disease, people may work a little harder to stave off cognitive decline and Alzheimer’s disease and that’s what makes studies like this important.

Your brain uses up to 20% of the oxygen that you breathe. How does it get from your lungs to those brain circuits that remember where you put your keys? Answer: your blood supply and your neurovascular system. This new study shows that the more fit you are the more efficiently you will get blood to your brain and the smarter you will be.

Studies like this may not provide us with earth shattering revelations. The results are not surprising, but they give us evidence that how we choose to live effects how we think and feel. And evidence leads to recommendations, which lead to policy changes, which hopefully, someday will lead to health care systems that promote and reward you to stay fit. So next time you’re struggling with whether or not to get off the couch and go for a walk, think about your brain – while you still can.

Reference:
Brown et al. Neurobiology of Aging (2009) In Press

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