When someone asks how old you are, you know the answer. (Whether or not you tell the truth, well, that’s up to you.) But what would you say if someone asked about your biological age? 

Most people never measure it. Douglas E. Vaughan, MD, a cardiologist at Northwestern Medicine and director of the Human Longevity Laboratory, explains how biological age is a key metric for creating strategies to improve longevity and quality of life.

Age is an important risk factor for all diseases in adults. “We believe that if we can slow down biological aging, we can delay the start of disease," says Dr. Vaughan. “We may be able to extend the healthspan of people.”

Working Together To Improve Healthspans

The Human Longevity Laboratory is the research arm of the Northwestern Medicine Human Longevity Clinic. Here is how they work together:

• The lab performs clinical studies to measure how different conditions affect biological age, such as chronic HIV infection, childhood cancer, breast cancer treatment and long COVID.
• Based on these studies, the lab runs clinical trials to find ways to slow the rate of aging. 
• Results are then used by the Human Longevity Clinic to provide clinical services and practical guidance that may help extend the healthspan (the number of years a person lives in good health).

Why Aging Isn’t the Same for Everyone

Sure, aging is inevitable, but it’s not at the same pace for everyone. Research shows that different organs age at different speeds. Some organs wear down faster because of their role in metabolism, exposure to stress and variable capacity to regenerate.

For example, blood vessels in the aorta start aging as early as your 30s, while the brain and immune system often hold up better. You can also look at the liver, which has extraordinary regenerative capacity. This uneven aging matters because when one organ declines early, it can raise your risk for disease even if the rest of your body is healthy.

How Organ Age Predicts Disease Risk

Organ-specific aging can predict health risks. A fast-aging heart raises the risk of cardiovascular disease. An older brain increases dementia risk. When multiple organs show accelerated aging, the risk of chronic illness and early death rises.

On the flip side, research shows that people with resilient brains and immune systems tend to live longer and stay healthier.

How AI Measures Biological Age

New technology now makes it possible to measure how fast your body is aging before symptoms appear.

• Retinal age tests: Your eyes are windows to your health. AI-powered retinal scans can spot tiny changes in blood vessels that signal early heart or brain problems. These tests may detect warning signs of:
• Diabetes
• High blood pressure
• Kidney disease
• Dementia (years before symptoms appear)
• Epigenetic clocks: Think of these as “biological age” trackers. They measure chemical tags on your DNA that change over time. Some clocks estimate your chronological age, while others predict disease risk and lifespan. The exciting part? These clocks can show improvements within weeks or months after lifestyle changes like better diet, exercise or medication.
• Proteomic age and PAI-1: Blood proteins tell another story about aging. A higher “proteomic age” — or how old your body appears based on the proteins in your blood — often means higher risk for heart disease and metabolic issues. One protein, PAI-1, is linked to blood clotting and blood vessel stiffness. Elevated levels can signal increased risk for diabetes, hypertension and coronary artery disease.

“The molecular profiling of aging is getting better,” says Dr. Vaughan. “We just secured the acquisition of a remarkable new technology that allows us to measure thousands of proteins at once. This will be incorporated into our protocols in 2026 and will improve our ability to measure systemic and organ-specific biological age.”

Patients at the Human Longevity Clinic also undergo these tests to measure key biomarkers of aging:

• Neurocognition tests, including cognitive, olfactory (sense of smell) and auditory assessments
• Heart and vascular tests
• Pulmonary function tests
• Musculoskeletal tests, including body composition and strength, gait or walking speed, and balance assessments

By using these different tests, Dr. Vaughan and his team gain a comprehensive view of the body, helping them develop evidence-based strategies to slow aging.

Longevity Studies in Progress

Research at the Human Longevity Laboratory at Northwestern Medicine is uncovering ways to slow aging, including:

• Power of PAI-1: Research in an Amish community in Indiana revealed a rare genetic mutation that slows aging and protects against chronic disease. Very low levels of PAI-1 is the key. Clinical trials are planned to see if blocking PAI-1 can help improve metabolic health and slow aging.  
• Stress reduction: Studies are underway to see whether a digital well-being program developed at Northwestern University can lower biological age. “We all think that stress makes us age more rapidly,” says Dr. Vaughan. “But what’s the science behind it? We want evidence that proves if you slow stress down, you can turn back the clock.”
• Breast-milk-derived nutrients: Human milk oligosaccharides (HMOs) are non-digestible sugars that promote infant gut health. Research is finding that HMOs may help the digestive health of adults, especially those with conditions like irritable bowel syndrome (IBS). Experts continue to look into the rejuvenating effect of these nutrients.

6 Daily Habits To Lower Biological Age

Dr. Vaughan shares six habits you can start today:

1. Move more and add strength

Physical activity lowers the risk of heart disease, heart attack and stroke, Type 2 diabetes, certain cancers and depression. Walking, jogging — any aerobic exercise is good for you. Adding strength work into the mix is even better.

Exercise regularly and consider these tips:

• Aim for 150 minutes of moderate activity per week.  
• Do muscle‑building exercises at least two days a week (use weights, resistance bands, and moves like squats and pushups).
• Focus on maintaining your lower and upper body muscle mass to protect bones and prevent falls, which is crucial as people age.

More muscle also helps regulate blood sugar, improve heart function, reduce inflammation, and support overall metabolic and physical resilience against many chronic illnesses.

2. Eat fewer ultra-processed foods

Ultra‑processed foods are ready‑to‑eat products high in added sugars, refined grains, fats and additives. These foods are linked to higher risks of Type 2 diabetes, obesity, high blood pressure and depression. Focus on whole foods and plenty of fruits and vegetables. Get inspired to craft a heart-healthy diet.

“Caloric restriction has been proven to be helpful in terms of extending the lifespan of animals,” says Dr. Vaughan. “Processed foods seem to trick our brain into thinking that we're starving, so we keep on eating. This makes it harder to manage the number of calories we eat.” 

3. Be mindful about stress

Your body’s cells know when you’re stressed. Chronic stress can affect sleep, raise blood pressure and increase inflammation. Build daily stress‑reduction habits, such as gratitude, mindful breathing and positive emotions to minimize stress when possible.

4. Sleep on a schedule

Sleep isn’t just about how many hours you get; going to bed and waking up at regular times may predict health and longevity even better than duration. Aim for seven to nine hours for adults and keep bedtime and wake time consistent. It also may help if you know your best sleep position for better rest.

5. Get social (in real life)

SuperAger research at Northwestern Medicine shows that older adults with warm, trusting relationships and social engagement have slower memory decline.

6. Know your environment

Outdoor air quality matters for heart and lung health. On days with high pollution, limit intense outdoor exercise. Close windows and run the HVAC on “recirculate.” Use a HEPA (high efficiency particulate air) filter if you have one.

Beyond the six daily habits, Dr. Vaughan notes that avoiding risky behavior is also part of a healthy lifestyle and increases your healthspan. Behaviors to avoid include:

• Smoking
• Drinking alcohol in excess
• Taking nonprescription drugs and self-medicating

Looking Ahead

The goal of the Human Longevity Laboratory is to find safe, effective, scalable and affordable ways to slow down aging in everyone, particularly people who have chronic conditions or difficult circumstances.

“We want to be the source of truth for anti-aging strategies grounded in science,” says Dr. Vaughan. “If we can extend the healthspan for even a few years, that’s a big win for our healthcare system — for everybody.”

In the near future, AI-powered tests could become part of routine checkups, helping medical professionals create personalized plans for long-term health. The challenge is making these tools affordable and widely available.

Aging isn’t just about counting birthdays. It’s about understanding your body and using that knowledge to live healthier, longer.