A digital map of aging brains has been created at the University of Edinburgh and could soon help provide a roadmap in the diagnosis of Alzheimer’s disease (AD).
MRI “atlases” of the brain are not new, but most are based on the brains of younger or middle-aged people and don’t reflect normal changes associated with aging. The atlas created by the University of Edinburgh, showcased in a study published online in PLOS ONE, is the first nonparametric MRI atlas based on scans of older individuals.
“Comparison of individual scans with atlases of normal older subjects may assist in future to diagnose faster-than-usual brain tissue loss in prodromal dementia, or to diagnose types of established dementia by differentiating patterns of abnormal brain tissue,” wrote David Alexander Dickie, PhD, of the University of Edinburgh's Brain Research Imaging Centre, and colleagues. “We have demonstrated that much of the cortex and subcortical [grey matter] voxels are not distributed approximately Gaussian in normal ageing. We therefore conclude that nonparametric atlases may be useful when assessing possible neurodegenerative disease in older age.”
Dickie and colleagues created the atlas from brain MRIs of 138 normal subjects aged 60 or older. The authors estimated parametrically the percentile ranks and limits of normally aging grey matter, but they also created a nonparametric, rank order-based grey matter atlas from the same normal subjects.
Comparing the scans of 138 subjects diagnosed with AD to the atlas, Dickie and colleagues found the parametric atlas returned some perplexing results, while the nonparametric identified more abnormal tissue. Specifically, in about half of the AD subjects, 25-45 percent of voxels—mainly in the frontal and occipital lobes—were classified as normal when compared to the parametric atlas but classified as abnormal when compared to the nonparametric atlas.
"We're absolutely delighted with these preliminary results and that our brain MRI atlases may be used to support earlier diagnoses of diseases such as Alzheimer's,” said Dickie in press release. “Earlier diagnoses are currently our strongest defense against these devastating diseases and, while our work is preliminary and ongoing, digital brain atlases are likely to be at the core of this defense."