What exactly does healthy aging look like?
Thanks to data from the Canadian Longitudinal Study on Aging (CLSA), researchers at Simon Fraser University have pinpointed the ideal range for 142 physiological traits that they found in exceptionally healthy seniors. Their study was published in GeroScience.
The work was led by Lloyd Elliott, assistant professor of statistics and actuarial sciences at SFU, and Angela Brooks-Wilson, SFU’s Dean of Science and Distinguished Scientist with the BC Cancer Research Institute.
The CLSA gives a wealth of information on human health as we age. CLSA started recruiting participants 2009 and now includes over 50,000 Canadians between the ages of 45 and 85, with plans to follow them for at least 20 years. Data are collected on biological, medical, psychological, social, lifestyle and economic measures. Researchers can then analyze the dataset to understand how each factor can contribute to health, disease, and disability.
In this particular study, the research team looked at healthy aging through the lens of homeostasis: a term that describes how the body strives to maintain a consistent environment even as potential disruptions come up. In health, traits like body temperature, blood glucose, blood pressure, electrolytes, or oxygen levels are all tightly regulated within an optimal range.
By contrast, when these parameters fall outside their optimal ranges, that imbalance can be a signal of poor health. When an infection strikes, inflammation can result in a fever that throws body temperature off the mark. When blood glucose levels start to drift higher, there is an increased risk of diabetes and all of its potential complications.
“This work allowed us to identify unrecognized features of healthy aging,” said Brooks-Wilson in a press release.
“In healthier groups, measures important for health tend to be closer to optimal values. This provides a way to identify traits that were not previously understood to be important for health, by looking to see if the measures for a trait are closer together in the healthy group.”
The study divided seniors up into four groups from the healthiest to the least healthy, assigning scores based on frailty, chronic conditions, cognitive and physical function, and diagnosis of a major disease like cancer. Next, over 200 measurable traits were examined, including vital signs, blood chemistry, inflammation markers, and body composition.
The team found 142 traits where the healthiest group was able to keep their measurements closer to a particular “sweet spot” compared to their peers in the least healthy group where more variability was measured. These traits draw a picture of what healthy aging looks like.
Blood chemistry was a notable area where many of these traits were found. The authors point to one biomarker in particular that can point to good health when kept in an optimal range: hemoglobin A1c, which is an indicator of average blood glucose levels over the past few months.
Body composition measurements were also significant predictors of health status, including body mass index (BMI), hip circumference, body weight, and the amount of lean and fat tissues.
Overall, the work demonstrates a new way to look for sweet spots that are important to health. This approach looks for differences in people with excellent health versus those with health deficits, and it may be more sensitive than looking at all-cause mortality. It may give more insight into earlier stages of health decline when it is still possible to take proactive steps back towards health.
This work also revealed ultra healthy ranges for many traits, often stricter than what is medically considered to be normal, putting a finer point on where to aim. Understanding the optimal ranges for these traits can help people strive towards for better health at any age.
