Scientists predict age with saliva sample

Are you self-conscious about your age? Then you may need to be careful where you spit. University of California Los Angeles (UCLA) geneticists can now use saliva to reveal how old a person is.

Principal investigator, Dr Eric Vilain, said the research team’s approach supplied one answer to the “enduring quest for reliable markers of ageing”.

“With just a saliva sample, we can accurately predict a person’s age without knowing anything else about them,” he said.

Dr Vilain and his colleagues looked at a process called “methylation”,  a chemical modification of one of the four building blocks that make up our DNA.

“While genes partly shape how our body ages, environmental influences also can change our DNA as we age,” Dr Vilain explained.

Methylation patterns shift as we grow older and contribute to ageing-related diseases.

Using saliva samples contributed by 34 pairs of identical male twins aged 21 to 55, UCLA researchers scoured the men’s genomes and identified 88 sites on the DNA that strongly correlated methylation to age.

The researchers replicated their findings in a general population of 31 men and 29 women aged 18 to 70.

Next, the scientists built a predictive model using two of the three genes with the strongest age-related linkage to methylation. When they plugged in the data from the twins’ and the other group’s saliva samples, they were able to correctly predict a person’s age within five years, which is said to be an unprecedented level of accuracy.

Researcher, Sven Bocklandt, said methylation’s relationship with age was “so strong” scientists could identify how old someone was by examining just two of the three billion building blocks that make up our genome.

In a minority of the population, methylation does not correlate with chronological age. Using this data, scientists may one day be able to calculate a person’s “bio-age”, which is the measurement of a person’s biological age versus their chronological age.

Physicians could evaluate the risk of age-related diseases in routine medical screenings and tailor interventions based on the patient’s bio-age rather than their chronological age. For instance, rather than requiring everyone to undergo a colonoscopy at age 50, physicians would recommend preventive tests according to a person’s bio-age.

“Doctors could predict your medical risk for a particular disease and customise treatment based on your DNA’s true biological age, as opposed to how old you are,” Dr Vilain said.

The UCLA team is exploring whether people with lower bio-age live longer and suffer less disease.