MRI brain age gap could flag who's heading toward dementia

A new study published in Neurology suggests that an MRI-derived measure called brain-predicted age difference (brain-PAD) — which compares how old the brain looks versus how old a person actually is — can help predict who will progress to dementia. Researchers studied 799 memory clinic patients with either subjective cognitive decline (SCD) or mild cognitive impairment (MCI) over a median follow-up of 3.2 years.

The findings were especially notable in SCD patients, where brain-PAD added meaningful predictive value on top of standard visual MRI assessments and even amyloid status. In the MCI group, however, brain-PAD didn't independently improve predictions once visual MRI findings were accounted for.

By the Numbers

• 799 patients studied (412 SCD, 387 MCI); mean age 63.3 years
• 29.4% progressed to dementia over a median 3.2-year follow-up
• Each additional year of brain-PAD was associated with a 6% increased dementia risk (HR 1.06)
• Negative predictive value at a brain-PAD threshold of −2.6 years: 0.99 at 2 years, 0.91 at 10 years

Why it matters: Identifying dementia risk earlier — before significant cognitive symptoms appear — is a major clinical goal. Brain-PAD could become a non-invasive, scalable tool to help clinicians stratify risk and prioritize interventions, though external validation is still needed before routine clinical use.