Chronological Age vs. Biological Age

Photo of Dr. Balbir Brar.
Dr. Balbir Brar, photo courtesy of Dr. Balbir Brar.
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What’s the difference, and what can you do about it? 

By Jim Walker 

In general, we sort of expect a person of a certain age to look a certain way. But every now and then, we meet someone who appears much younger or older than their actual age. And, while appearances can be deceiving, possibly the result of plastic surgery, these encounters point out that each of us has two ages – chronological and biological.  

Your chronological age, the one based solely on your birthday, simply indicates the number of years you have been alive. However, your biological age, or physiological age, is how old your body “seems” in look and performance. Biological age is much more important than chronological age, as it is intimately involved with our health, abilities and outlook. And, while how we age (how fast our cells deteriorate) is influenced by genetics, it is also affected by, among other factors, smoking, diet, exercise and stress.  

Dr. Balbir Brar, MD, MPH, is a board-certified physician specializing in internal medicine and palliative medicine. He serves as chairman of medicine at Henry Mayo Newhall Hospital and is on the faculty at David Geffen School of Medicine at UCLA. He has extensive experience in treating age-related issues in his practices of geriatrics and internal medicine, and advises us on the rapidly expanding field of study regarding biological age. 

“Genetics plays a significant role, possibly 10 to 20%, in how we age,” Brar said. “Other determinants of biological aging include environmental effects, eating habits, demographics and lifestyle. The study of aging is a hot topic and especially so with the investigations going on at the National Institute on Aging,” he said. “Various companies and institutions are promoting diagnostic testing, and also therapies – which may or may not be supported by scientific evidence.”  

How is biological age determined? 

Current studies indicate epigenetics, the chemical changes that happen to our DNA sequence, might be the scientific window into biological aging. To that point, research shows that DNA methylation and things called telomeres have big influences on aging.  

DNA methylation controls gene expression. It can “turn genes off.” This controls things like embryonic development and chromosome stability. And, thus, through methylation, certain areas of the body – breast tissue, for example – can be “older” than the rest of the body, and so more susceptible to cancer. “Both increased and decreased DNA methylation can affect the aging process, positively or negatively,” Brar said. 

Telomeres are located on the ends of chromosomes, and determine how quickly our cells age and die. “In studies on animals, telomere deficiency leads to shortened lifespan, increased malignancies and genomic instability,” he said. 

Biological Age Tests  

There are a number of companies marketing “tests” to determine biological age. Accuracy varies and some claims of accuracy are unproven. One well-known test is merely a questionnaire, and more a predictor of life expectancy than an age calculator. Another tests the DNA in your saliva for methylation. With another, you can plug your most recent blood test results into a calculator – things such as albumin, cholesterol, platelets, electrolytes – along with such information as your height and weight. Another test has you prick your finger and send in a blood sample, which is tested for the levels of things called glycans.  

“The most popular diagnostic testing involves the study of epigenomes, which are chemical compounds attached to the DNA,” Brar said. “And the thousands of sites on a DNA strand are studied, with subsequent calculations to determine the approximate biological age.” This test is usually done using saliva from the mouth. Brar added that “good” tests of biological age will all have a result within one year of each other. “If they are way off, there is possibly a reason for it,” he said. 

Improving biological age 

Getting an accurate determination of your general biological age can help you decide if your health-maintenance efforts (or lack of them) are working. If not, it’s time to change things up. Know that maintaining a healthy lifestyle can actually reverse aging to a certain degree, but this is not guaranteed. You can eliminate bad habits, such as smoking and excessive use of alcohol, improve your diet, try intermittent fasting, get regular exercise, and reduce environmental toxins. “Doing these things will have a positive impact on aging,” Brar said. “However, one must be careful in pursuing ‘therapies’ that are unproven, and often costly, without first consulting their physician.” 

Reduce stress 

Chronic stress accelerates premature aging by shortening your telomeres and increasing methylation. Such stress can also limit your immune system and increase your chances of chronic disease. These include, but are not limited to, stress at work (and burnout), stress in personal relationships, and stress resulting from too much focus on social media or too much absorption of upsetting television news. “Burnout at work can be a big factor in feeling old, and therefore, it’s wise for employers to take a practical approach to it,” Brar said. And he added that caregivers are particularly impacted by stress. 

Psychological aging 

“Perception of age is psychological age (or subjective age),” Brar said. For example, if you are 60 and say you feel like you are 50 (or 70), that’s psychological age. “In addition to tests for biological aging, there are tests for psychological aging that are available in the form of questionnaires. Studies have shown that people who perceive themselves to be younger psychologically have less disease and tend to live longer. Perception of expected prolonged survival leads to better selection and pursuit of social goals, as opposed to perception of limited survival, which will cause emotion-based decisions.”  

Better for all 

“There is a relationship between biological and psychological aging and the quality of life,” Brar said. “Attempts to slow down biological aging will lead to a society that is healthier, more productive, and, more importantly, more self-fulfilling on our journey of life. But don’t go to extremes in lifestyle modification or extreme therapies.” 

Dr. Balbir Brar can be reached at Henry Mayo Newhall Hospital, 

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