• Chronological age measures the time that has passed since someone’s birth.
• Biological age estimates how old someone’s body is by examining several biomarkers.
• Data from a recent study found that high biological age may raise the risk for certain neurological conditions, including all-cause dementia and ischemic stroke.

Biological age helps to measure how fast someone’s body systems are aging. Biological age may differ from someone’s chronological age.

Researchers are still seeking to understand the benefits of calculating biological age, including how it can identify risk for certain health conditions.

A recent study published in Journal of Neurology, Neurosurgery & Psychiatry examined how biological age increased the risk for specific neurological problems.

Researchers found that advanced biological age was associated with an increased risk for all-cause dementia, vascular dementia, and ischemic stroke.

They also found weak positive associations between advanced biological age and Alzheimer’s disease (AD) and motor neuron disease (MND). The results indicate the importance of monitoring biological age and furthering research into improving biological age.

How is biological age determined?

Biological age and chronological age measure slightly different components related to aging.

Biological age has to do more with how a person’s body is aging. Chronological age is the amount of time that has passed since someone’s birth, as researchers of this study note.

Non-study author Dr. Sandra Narayanan, board certified vascular neurologist and neuro-interventional surgeon at Pacific Stroke & Neurovascular Center at Pacific Neuroscience Institute in Santa Monica, CA, explained to Medical News Today:

“Chronological age is time since birth and is measured in absolute terms (i.e., years). Biological age describes the more subtle physiological processes that influence how old or dysfunctional one’s cells and tissues are.”

Researchers can look at certain biomarkers to estimate biological age. Some biomarkers that may help measure biological age include components like:

• systolic blood pressure
• cholesterol
• serum creatinine
• albumin
• lymphocytes
• red cell distribution width

The precise biomarkers researchers examine to calculate biological age are still being studied.

Researchers of this current study used three measures of biological age in their analysis, ultimately looking at 18 biomarkers. Examples of these biomarkers included:

• blood pressure
• waist circumference
• creatinine
• albumin
• serum glucose
• C-reactive protein

How does biological age impact neurological health? 

For the present study, researchers wanted to understand the relationship between certain neurological disorders and biological age.

Researchers used data from the UK Biobank in their analysis. In total, their research included 325,870 participants. They excluded participants for a few reasons, including missing data on biological age and previous history of dementia, ischemic stroke, Parkinson’s disease, or motor neuron disease.

They looked at the data for biological age. Then, they analyzed this in relation to several conditions, including all-cause dementia, vascular dementia, and ischemic stroke. The average follow-up time for participants was nine years. Researchers accounted for several covariates in their analysis, including factors like smoking and alcohol use and body mass index.

During the follow-up time frame, 1,397 participants developed dementia, and 2,515 experienced ischemic stroke.

Based on their analysis, researchers found that more advanced biological age was associated with an increased risk for all-cause dementia, vascular dementia, and ischemic stroke. The evidence was most substantial for these associations. However, researchers also found that advanced biological age may also increase the risk for Alzheimer’s disease and motor neuron disease.

Study author Sara Hägg, PhD, associate professor at Karolinska Institutet, Stockholm, Sweden, research group leader in the field of molecular epidemiology of aging, explained to MNT:

“Assessments of human biological aging can be made in many different ways. In this study we used a composite score of clinical biomarkers. We showed that an advanced biological age compared to what is expected at that chronological age is associated with neurological disorders. We have similarly showed this for other age-related diseases as well. Staying healthy as long as possible to maintain body functions and keep a low biological age is hence beneficial to avoid late-life diseases.”

More research on the health effects of biological age needed

Despite the compelling findings, this research does have some limitations.

First, it cannot be established that higher biological age causes any health-related conditions researchers examined. The data also only used data from the UK Biobank, which means the results cannot necessarily be generalized to all populations.

Participants in the UK Biobank tend to be healthier than the general population. Some data also relied on participant self-reporting, which can lead to incorrect data.

Researchers note that some assessments of biological age could have occurred while participants were in the early phases of certain conditions. However, researchers conducted a sensitivity analysis that excluded participants if their condition was diagnosed within five years of their biological age assessment.

They also note that the biomarkers of the biological age measurements limited them. Many of these biomarkers are also associated with stroke and all-cause dementia on their own and may also reflect cardiometabolic health.

Further research will need to be conducted in this area to understand the possibilities of slowing biological aging. Dr. Narayanan noted the following to MNT:

“It is useful to understand modifiable and nonmodifiable risk factors for neurological illness for the benefit of disease management and patient counseling. While chronological age is non modifiable, it is striking that measures of biological age (BA) — which has a strong association with all-cause dementia and ischemic stroke — may be a modifiable risk factor, as these BA markers are more commonly present in patients with vascular comorbidities (hypertension, smoking, diabetes, hyperlipidemia). Once researchers and physicians understand this connection better, they can educate patients and families [how] best to prevent cerebrovascular disease and dementia and to optimize longevity and quality of life in these populations.”

Study author Johnathan Mak, a PhD student at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, noted to MNT:

“While our study provided valuable insights, it is important to note that it was an observational study, which means we cannot establish causality. Our future work will continue to study connections between genetic background, biological aging and other major age-related diseases. We believe this can enhance our understanding of the underlying mechanisms and potentially lead to new preventive strategies and treatments.”

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