There's your calendar age, and then there's what scientists call your "biological" age, which is based on various measurements indicating good or not-so-good health.

Now, new Swedish research finds that less healthy folks, with a biological age that outstrips their chronological age, may be at higher odds for dementia and stroke.

“But because people age at different rates, chronological age is a rather imprecise measure”, explained study lead author Sara Hägg, an associate professor in the department of medical epidemiology and biostatistics at the Karolinska Institute in Stockholm.

In the study, Hägg's group tracked markers such as measurements of blood fats, blood sugar, blood pressure, lung function and BMI, to better assess a person's biological age.

They then looked at data on over 325,000 Brits included in the UK Biobank database. Hägg's team looked at biological age "biomarkers" for individuals and then compared nine-year rates for neurological illnesses such as dementia, stroke, ALS (Lou Gehrig's disease) and Parkinson's disease.

Two of the conditions stood out.

“If a person's biological age is five years higher than their actual age, the person has a 40 percent higher risk of developing vascular dementia or suffering a stroke,” said study co-leader Jonathan Mak, a Karolinska doctoral student.

Risks for ALS also rose with increasing biological age, but there was no effect seen when it came to Parkinson's disease.

The study wasn't designed to prove cause-and-effect, but it's very possible that getting healthier might reduce any excess risk to the brain, the researchers said.

“Several of the values can be influenced through lifestyle and medications,” Hägg noted in an institute news release.

The study was published Nov. 5 in the Journal of Neurology, Neurosurgery and Psychiatry.