Brain age gap

The brain age gap is one of the most widely used neuroimaging biomarkers. It is the difference between a person's brain age — estimated from an MRI scan — and their chronological age.

A gap of +8 years means the brain looks structurally about eight years older than the calendar would suggest. A gap of −5 years means it looks five years younger.

Why it carries information

The gap behaves like a sensitive summary of accumulated brain wear and protection. Larger positive gaps are associated with:

• Hypertension, diabetes, and other cardiovascular risk factors
• Poor sleep over years
• Heavy alcohol use
• Stroke and other focal neurological injury
• Several psychiatric and neurological conditions

Larger negative gaps (or stable, small gaps over time) are associated with:

• Regular aerobic exercise
• Continued education and cognitive engagement
• Social connection
• Adequate sleep

In research

The brain age gap is increasingly used as a biomarker in:

• Trial endpoints — does an intervention slow the rate at which the gap grows?
• Risk stratification — patients with larger gaps may benefit from earlier or more intensive care
• Mechanism studies — what does the gap actually capture, biologically?

Caveats

The gap depends on the model. Different models trained on different reference populations produce different numbers. Cross-population validity (e.g., applying a model trained on UK Biobank to a Ghanaian cohort) is an active research question and one of the reasons we built Neureka.

Read more

• Two ages, one body
• How stroke accelerates brain ageing