While your chronological age will tell you how long you've been riding around on this planet, your biological age might actually be a more important number, as it tells you how well your body is faring on its journey. Now, researchers at Imperial College London have added to the growing toolbox of biological age determinants by examining images of our brains.

About two years ago, researchers developed a test that could determine your biological age by searching for 150 active genes in the blood. That's also about the time that researchers came up with a different way of determining biological age by examining urine samples. Now, the IC London researchers believe they have found yet another way to determine how well we're aging by combining MRI scans of the brain with machine-learning algorithms. If their method is perfected and verified, finding out our biological age might be as simple as getting a picture snapped of our noggins.

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The technique at the heart of the new method was actually initially developed in 2010 and involves using machine learning to analyze measurements of brain volume to estimate the total loss of grey and white matter, a process that naturally occurs as we age.

The twist on the process, which has been described today in the journal Molecular Psychiatry, involves comparing the reduction in brain volume seen in MRIs to a standard developed by examining the brains of 2,000 healthy people. In other words, the 2,000 healthy MRIs were used to create a map that shows what a healthy brain should look like. By comparing new scans to this data, researchers are able to see how much brain matter has been degraded and come up with a biological age for the patient.

In verifying the technique, the researchers used data from a group known as the Lothian Birth Cohort 1936, a well-observed collection of individuals who all had MRI scans of their brains at age 73. They found that if the scans revealed such a degradation of grey and white matter that the brain appeared older than the person's biological age, those people had worse results on standardized tests for aging such as lung capacity, grip strength and gait speed. Also, if the brain appeared older than the participant's chronological age, he or she was statistically more likely to die before reaching 80 years of age.

The technique currently has an error value of five years, so it will need to be refined further before it could become a valid measurement of biological age, but the researchers are hopeful that they'll get there, perhaps even using brain age as a health indicator in much the way body mass index (BMI) is used today.

"In the long run it would be great if we could do this accurately enough so that we could do it at an individual level," said James Cole, an IC London research associate in the Department of Medicine, who led the study. "Someone could go to their doctor, have a brain scan and the doctor could say 'your brain is 10 years older than it should be,' and potentially advise them to change their diet or lifestyle or to start a course of treatment. However, at the moment, it's not sufficiently accurate to be used at that sort of individual level."

Source: Imperial College London