An international study appears to have created a test that can determine the biological age of a patient's body. The research – undertaken by King's College London (KCL), the Karolinska Institutet in Sweden, and Duke University in the US – could have a broad range of applications, including improving screening techniques for age-related diseases such as Alzheimer's, allowing doctors to begin treatment earlier in the process.

Before delving into the importance of the research, we have to understand the difference between chronological age and biological age. Your chronological age is your age in years, days and minutes from the moment you were born. Whilst all people age chronologically at the same rate, our bodies run on a separate biological clock, meaning that the bodies of two people at the chronological age of say 50, could have significantly disparate biological ages.

Prior to the new research by KCL et al, there had been no reliable tool to accurately determine a person's biological age, a factor synonymous with neurological diseases. The seven-year experiment saw the team examine thousands of tissue samples from subjects of the same chronological age, subjecting them to a test known as RNA profiling. Through this approach, it was discovered that the activation of 150 genes in the blood, brain and muscle tissue of an individual at the chronological age of 65 constituted the biological markers of being in good health.

Using this discovery as a basis, the researchers were then able to create a formula for healthy aging. A low score based on the formula carried the hallmarks of cognitive decline. In an interesting twist, the samples examined as part of the study appeared to dispute the idea that biological age may result from an individual's lifestyle choices.

The team believe that the molecular test developed during the research could be easily translated into a blood test that could provide early indications of the onset of a degenerative disease such as Alzheimer's, which is currently known to affect 5.1 million people in America alone.

The results of the study have potential applications reaching beyond dementia research. The ability to accurately discern a person's biological age could significantly increase the success rate of organ transplant surgeries, by matching the biological age of the patient with that of the donor.

The next step in the project will be to determine why these differences in biological age occur, with an eye to attacking age-related diseases at their source.

A paper on the research can be found in the online journal Genome Biology.