Key Points:
- Our “cardiovascular age” progresses at a rate similar to our chronological age, while the relative age of our other organs and systems can be older or younger.
- The age of our cardiovascular system and liver can predict whether we may have heart or liver disease.
- The genes associated with the age of our skin can predict longevity.
Our organs are like parts of a biological machine, working together to keep us alive. If one part of the machine becomes old and damaged, the whole machine can break down. To help prevent this inevitable system failure, we can assess the condition of each part. We could even predict how long the machine will last by knowing the condition of each part. How do we assess the condition of our organs? A new study published in Cell Reports shows how this is possible.
Using hundreds of biomarkers, many of which can be obtained by routine physical checkups or blood samples, the Bejien Genome Institue (BGI) Group and China National GeneBank (CNGB) in Shenzen were able to determine the biological age of different organs and systems in younger adults. This detailed calculation of organ age predicted mortality and even specific diseases. Furthermore, Nie and colleagues showed that the genes associated with the age of our largest organ, the skin, can predict if we will live beyond 100-years-old.
Our Organs Age at Different Rates
While we all age at the same rate chronologically, our biological age – age based on biological markers – can more accurately predict how long we will live and if we will have age-related diseases. Breakthroughs and advancements in biomedicine and technology in the past 50 years have allowed us to determine biological age more accurately. By analyzing a repertoire of biological measurements, Nie and colleagues were able to develop the most detailed determination of biological aging to date.
Blood and stool samples, physical fitness examinations, and facial skin images were obtained from 4,066 Shenzen volunteers (48% males) between the ages of 20 and 45. From this, 403 features were measured, ranging from body composition to vitamin level. The features were classified into nine categories: cardiovascular, renal (kidney), liver, sex hormones, facial skin, nutrition/metabolism, immune-related, physical fitness, and gut microbiome (microorganisms that live in our gut).
(Nie et al., 2022 | Cell Reports) Biological Aging Determined from Multiple Angles. Data was obtained from each participant through multiple methods, encompassing several organs and physiological systems as well as body-wide fitness.
Using the hundreds of measurements obtained from the participants, the age of each of the nine organs/systems was determined. The Shenzen researchers found that “cardiovascular age” was most highly correlated with chronological age. The age of the other organs/systems were either decelerated or accelerated relative to chronological age, indicating that our organs age at different rates.
Which organs or physiological systems aged the slowest or fastest? This was highly variable and depended on the individual. However, “physical fitness age” was associated with slower aging in almost all the other organs/systems. This may come as no surprise, as being physically fit has been shown time and time again to promote health and longevity. This data suggests that being physically fit can slow down the aging of our organs.
Biological Age and Organ Age Predict Death and Disease
What can we do by knowing the age of our organs? With their detailed determination of biological aging, Nie and colleagues could predict mortality and disease. Using a National Health and Nutrition Examination Survey (NHANES) dataset from the United States, they found that cardiovascular age predicted death from heart disease better than risk factors for heart disease separately (e.g., chronological age, fats, cholesterol, blood pressure, and blood glucose). This finding demonstrates that the age of our cardiovascular system can be used to predict whether we will have heart disease.
Furthermore, from the Shenzen dataset, the occurrence of non-alcoholic fatty liver, the most common disease in the study sample was predicted by liver age. This finding demonstrates that the age of our liver could be used to predict whether we will have liver disease. By combining the ages of our organs to obtain an overall biological age, the Chinese researchers also showed that they could predict mortality better than chronological age, consistent with previous reports. Overall, these findings demonstrate that biological age and organ age can accurately predict mortality and disease.
Genes Associated with Skin Aging Predict Longevity
Are there genetic factors associated with our orgrans/systems that can predict how long we will live? To predict longevity, Nie and colleagues analyzed a dataset from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), which includes 2,178 centenarians (aged 100 years and above) and 2,299 middle-aged controls. For each organ/system, the researchers searched for genes common amongst centenarians to look for genes that might be associated with longevity. They found that the genes linked to skin age predicted longevity better than any other organ/system. These findings suggest that the genes associated with the quality of our skin can predict whether we will live beyond 100-years-old.
(Nie et al., 2022 | Cell Reports) Skin Age Predicts Longevity. The genes associated with each organ/system were used to predict whether an individual was a centenarian. Skin age was able to predict this with the least amount of variability. The coefficient (orange square) represents the strength of the association between the genes of each organ/system and longevity. The error bars (lines left and right of orange squares) represent the variability, the accuracy of the prediction.
Using Biological Age for Preventative and Targeted Treatment
The findings of this study demonstrate that disease and mortality can be predicted by assessing the biological age of our organs and physiological systems. What makes these findings more significant is how biological age was determined.
“There has been a lack of practical applications in a population-based sample for precisely estimating the aging rates of live people’s organs and systems,” says author Xiuqing Zhang. “So we decided to design one.”
Not only does the study increase our knowledge of how the aging process works, it demonstrates the applicability of the methods used.
“Our study used approaches that can help improve our understanding of aging and — more importantly — could be used some day in real healthcare practice,” says author Xun Xu. “We used biomarkers that could be identified from blood and stool samples plus some measurements from a routine body checkup.”
By having our organ ages measured, we may someday be able to prevent specific diseases. Hypothetically, a 30-year-old individual could walk into a clinic and get their biomarkers measured. Within a few days, they receive word that their liver is far beyond the age of 30. Thus, the individual takes preventive measures to slow down the aging of their liver (i.e. drinking less alcohol) to prevent liver disease by the age of 60.
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