Researchers at Imperial College London analysed brain scans from
over 1,500 healthy people to develop a computer program that could
predict a person's age from their brain scan.
Then they used the program to estimate the "brain age" of 113
more healthy people and 99 patients who had suffered traumatic
brain injuries.
The brain injury patients were estimated to be around five years
older on average than their real age.
Head injuries are already known to increase the risk of
age-related neurological conditions such as dementia later in life.
The age prediction model may be useful as a screening tool to
identify patients who are likely to develop problems and to target
strategies that prevent or slow their decline.
"Your chronological age is not necessarily the best indicator of
your health or how much longer you will live," said Dr James Cole
of Imperial College London. "There is a lot of interest in finding
biomarkers of ageing that can be used to measure a certain aspect
of your health and predict future problems."
The study used magnetic resonance imaging (MRI) to study changes
in brain structure. The researchers used a machine learning
algorithm to develop a computer program that could recognise
age-related differences in the volume of white matter and grey
matter in different parts of the brain.
The model was then used to estimate subjects' ages based on
their brain scans. The study included 99 patients with traumatic
brain injuries (TBI) caused by road accidents, falls or assaults,
who had persistent neurological problems. The scans were taken
between one month and 46 years after their injuries.
In healthy controls, the average difference between predicted
age and real age was zero. In TBI patients, the difference was
significantly higher, with a bigger discrepancy in patients with
more severe injuries. Bigger differences in predicted age were
associated with cognitive impairments such as poor memory and slow
reaction times.
There was also a correlation between time since injury and
predicted age difference, suggesting that these changes in brain
structure do not occur during the injury itself, but result from
ongoing biological processes, potentially similar to those seen in
normal ageing, that progress more quickly after an injury.
"Traumatic brain injury is not a static event," said Dr Cole.
"It can set off secondary processes, possibly related to
inflammation, that can cause more damage in the brain for years
afterwards, and may contribute to the development of Alzheimer's or
other forms of dementia."
The researchers believe the age prediction model could be
applied not just to TBI patients, but might also be useful to
screen outwardly healthy people.
"We want to do a study where we use the program to estimate
brain age in healthy people, then see if the ones with 'old brains'
are more likely to get neurodegenerative diseases. If it works, we
could use it to identify people at high risk, enrol them in trials
and potentially prescribe treatments that might stave off disease,"
said Dr Cole.
The researchers were supported by the EU Seventh Framework
Programme, the National Institute for Health Research (NIHR) and
the NIHR Imperial Biomedical Research Centre.
The paper, Prediction of brain age suggests accelerated atrophy after
traumatic brain injury, is published in The Annals of
Neurology.