Brain scans might help identify those at risk of Alzheimer’s years before the first signs of the disease appear, research has shown.
Individuals with thinner regions of the brain’s cerebral cortex are significantly more likely to show early evidence of dementia, the study found.
Scientists looked at Magnetic Resonance Imaging (MRI) scans of the brains of 159 cognitively normal older people.
Three years later test results from 125 participants showed 21% of those with a thinner cerebral cortex showed signs of mental decline.
The same pattern was seen in just 7% of volunteers with a cortex of average thickness. Among volunteers with a thicker than average cortex there was no evidence of declining mental faculties.
The cerebral cortex is the outer layer of the cerebrum, the most highly developed part of the brain.
It consists of “grey matter” - the cell “bodies” of neurons where processing of muscle control, sensory perceptions, memory, emotions and speech take place.
Cerebral cortex thickness can vary from around 1.5 millimetres to 5 millimetres.
The researchers also looked at cerebrospinal fluid (CSF) samples from 84 participants after three years to check levels of amyloid protein, a hallmark of Alzheimer’s.
They found that 60% of people with a thinner cortex had abnormal CSF amyloid levels similar to those seen in the brains of Alzheimer’s patients.
This compared with 36% of those with average cortical thickness and 19% of those with an unusually thick cortex.
The research from scientists at Massachusetts General Hospital and the University of Pennsylvania is published online in the journal Neurology.
Bradford et al. MRI cortical thickness biomarker predicts AD-like CSF and cognitive decline in normal adults. Neurology, doi: 10.1212/WNL.0b013e31823efc6c