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Physiological Age: The Age That Matters

By Palina Piankova

“You should worry about inner beauty!”

Isn’t that what all mothers had to say at some point? Now, what if I told you that science agrees? Science agrees that a distinction exists between chronological age (the one marked by your birthday cake) and physiological age (determined by how well your body functions). This “inner beauty” (aka the physiological age) is the one that will carry you through retirement. It is the one that affects your longevity. Physiological age can be greater than the chronological one in the case of poor lifestyle choices, or on the opposite, can be found to be remarkable with good ones.

With the era of personalized health care moving upon us, many institutions have generated “calculators” that will estimate this “body age” based on a series of parameters that can be obtained from patient blood samples.

More and more, medicine agrees that patient standard care should be tailored to this physiological age. What can the body take on? How vulnerable it is to different stressors?

There is a normal increase in the body’s vulnerability state that appears with age, but it appears at different rates in different people based on the overall fitness of the body. Here, “fitness” does not refer to the number of benches presses you can do, but rather to how efficiently your body can work. This increased vulnerability increases the physiological age.

One of the factors that contributes to this normal decline as a result of age is known to the medical field as “frailty”. How fragile is your body? Can it easily break under pressure like a vase, or is it resistant as a rock?

Several scales attempt to quantify frailty. They include physical and cognitive components that yield in a score that can predict patient mortality after a year as an example.

Frailty indirectly permits to assess this physiological age and guide patient intervention. Will your body resist to the stress of an aggressive open-heart surgery, or will it rather prefer a more gentle approach?

In some cases, these less invasive approaches can buy you more time, but less autonomy in your daily activities. Or it can even buy you no time at all… There is a trade off to make. Time, quality, and the physical ability to withstand stress, all must be weighed in for the optimal clinical decision.

So how do you become strong on the inside, and ensure yourself more chronological years to follow, and increased vitality to (hopefully) enjoy your early retirement?

Again, mothers know best: eat well and exercise. No spoilers there! No secret trick, no Botox for the “insides”, no cheating is possible.

Your physiological age isn’t the one you can go against. Your body will remember, such is life. Science can do its best to quantify and estimate the phenomenon, and help tailoring health care interventions, but it cannot stop it, or turn the clock backwards.

The hope is to stay aware of such concepts and act in time by focusing on our “inner beauty”. Sixties can become the new twenties!

Thanks Mom.

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Neuroimaging and repurposed pain killers: choice weapons against Alzheimer’s disease

Comic by Brian Crane, continued below

By Caitlin Fowler

Despite a century of research, we are still firmly in the dark when it comes to understanding Alzheimer’s disease (AD), a condition that robs us of even the simplest memories, such as our own birthday. But, what if we could easily peek into the diseased brain to shed light on which specific areas we should be targeting with drugs? Neuroimaging provides this unique window into the brain and is allowing Dr. Jamie Near’s group at McGill University to study how a common pain reliever may double as a treatment for AD.

Dr. Near’s researchers use neuroimaging to study the brains of rats that have been genetically engineered to have AD. First, they take pictures of the entire brain using high resolution MRI (Magnetic Resonance Imaging) to see if the rat brain shrinks during AD as the cells start to die. Second, during these MRI scans they also “zoom in” on a small part of the brain and measure the concentration of about 20 different molecules using a technique called Magnetic Resonance Spectroscopy (MRS). The concentration of these molecules tells us whether the brain is healthy, or alternatively, if brain cells are inflamed and dying. These neuroimaging techniques can be performed many times during the lifetime of a rat (or human) without any side effects, and all the rat (or person) has to do is lie in the MRI machine for about half an hour. This means scientists have a relatively simple way of studying how AD affects the brain over time, and therefore, which areas to target with drugs.

One potential drug that could be used for this purpose is likely already in your medicine cabinet; we have all reached for an Aleve to deal with headaches or back pain, but what if it could also treat Alzheimer’s? In addition to studying how the brain changes during AD, Dr. Near’s group is also examining how the diseased brain responds to treatment with Naproxen (the active ingredient in Aleve). Naproxen is normally used to reduce inflammation and pain throughout the body, so Dr. Near is investigating whether it may also reduce brain inflammation, which is a large part of the disease process in AD. His group is using MRI and MRS to monitor whether treating their rats with Naproxen from an early age can slow down the unhealthy structural and chemical changes known to occur in the brain during AD.

The study is still ongoing, but if it is successful, doctors may one day be prescribing a daily Naproxen and a yearly MRI as a way to effectively manage a devastating disease that affects 50 million people worldwide, and ensure that no one forgets their own birthday.

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Comic of old couple, the man can't remember his birthday

originally designed by Brian Crane; published May 30, 2014.

What Makes Ticks Tick? Using Your Tick Encounters to Predict Lyme Disease Risk

A black-legged tick. Courtesy of: Robert Webster

By Jean-Paul R. Soucy

This lovely critter, no larger than a sesame seed, is a black-legged tick (Ixodes scapularis). This species’ bite is responsible for transmitting Lyme disease in most areas of Canada and the United States. Lyme disease affects thousands of Canadians each year and causes symptoms like fever, fatigue, and chills, which can turn into arthritis, neurological issues, and even heart problems if untreated.

Given the severity of this disease, it makes sense that we might want to know where in our environment this perilous parasite is likely to show up. This information can help public health authorities decide where to target pest control efforts or choose where to display warning signage. The black-legged tick dries out easily and generally prefers cool, damp environments such as under the leaf litter present in deciduous forests. However, the speed of the tick’s development is directly tied to climate, so areas that aren’t warm enough will mean that ticks in that area will be unlikely to develop and reproduce. Additionally, as a parasite, the black-legged tick needs access to specific animal hosts in order to complete its life cycle. There’s a lot to think about when it comes to figuring out where black-legged ticks might be!

The simplest way to discover if ticks are in a particular area is to go out and look for them. However, this is expensive and time-consuming and as a result can only be done over small areas. What if there was a way to predict the occurrence of black-legged ticks over a large area using data that already exist? Well, there is, using ticks submitted by members of the public for identification and disease testing (not all black-legged ticks carry Lyme disease). If these submissions mention where the tick was collected, we can correlate these points with the values of environmental variables (such as mean annual temperature or distance to water) at these points to detect if any of these variables are associated with the presence of ticks. These relationships can then used to make predictions about the presence of ticks anywhere in a region of interest. This process is called species distribution modelling. In my 2018 paper on Lyme disease risk in Ottawa, Ontario, we did just that using ticks submitted to Ottawa Public Health and free land cover data from the Ontario’s Ministry of Natural Resources and Forestry.

In this study, we considered a number of variables that might be connected to black-legged ticks, including the distance from treed areas, elevation, and the nearby availability of water. Our plan was to compare the values of these variables at the locations that members of the public had found ticks to the values of these variables at points randomly selected from the entire region of Ottawa. If tick presence was correlated with being close to trees, for example, we would expect our tick points to be closer on average to trees than points randomly selected from the whole region.

There’s just one problem with this approach—we haven’t accounted for bias in how our tick presence points were collected. Remember that people generally travel to places they can access easily; in other words, people tend to stick close to roads. If we try to make predictions without accounting for this bias, we would in fact be predicting where roads are, not ticks! Thus, to make the comparison fair, we have to compare the values of environmental variables at tick presence points to randomly selected points near roads in Ottawa.

Heat map predicted tick occurence Ottawa

Predicted tick occurrence in Ottawa, Ontario. Courtesy of: Soucy et al. 2018.

Above is our final map for predicted tick presence in Ottawa. Red areas are more likely to contain ticks, whereas blue areas are less likely. We tested our predictions by looking for ticks at 17 sites in Ottawa. The results of this study were largely consistent with our predictions, as we tended to find ticks (positive sites) in red areas but not find them (negative sites) in blue areas. Among the variables we studied, we found that distance from treed areas, distance from agriculture, and water availability best predicted tick presence.

How do we know that these variables actually cause tick presence, rather than just being correlated with them? Well, we don’t. This is where expert knowledge of tick biology comes in to identify plausible relationships. As previously mentioned, ticks thrive in the cool, damp environments provided by deciduous leaf litter. And deer, the hosts for the adult black-legged tick, require access to a reliable source of water.

I hope this post helps to shed some light on how researchers use data provided by citizens and governments (paid for by citizens!) in order to produce maps to assist with combating infectious disease threats.

If you’ve been bitten by a tick and would like to learn how to submit it for Lyme disease testing in Canada, please click here or contact your local public health authority. This project and others like it would not have been possible without the assistance of people like you.

Click here to learn how to avoid being bitten by black-legged ticks (Centers for Disease Control and Prevention).

You can read the full open access publication that inspired this post in Vector-Borne and Zoonotic Diseases.

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