A gene variant linked to late-onset Alzheimer’s may affect the brain’s workings early in life, decades before forgetfulness becomes apparent.
Publishing in PNAS (doi: 10.1073/pnas.0811879106), Clare Mackay from the University of Oxford, and colleagues at Imperial College London, scanned the brains of 36 healthy adults between 20 and 35 years old. Eighteen of the volunteers carried the ApoE4 allele of the APOE (apolipoprotein E) gene, which is associated with late-onset Alzheimer’s. About a quarter of the population have one copy of ApoE4, which for reasons unknown increases their risk of developing Alzheimer’s fourfold, says the Alzheimer’s association.
The volunteers were asked to do memory tests, and to do nothing, while hooked up to fMRI machines. Though all performed equally well on the memory tests, the APOE4 carriers showed greater activity in the hippocampus, an area of the brain involved in long-term memory. Other distinctive differences in hippocampal brain activity were spotted even when the volunteers did nothing. (The images show increased brain network activity for the APOE4 carriers, relative to non-carriers, while resting and performing memory tasks).
“These are exciting steps towards a tantalising prospect: a simple test that will be able to distinguish who will go on to develop Alzheimer’s,” said Clare Mackay, who led the study (press release).
“Not all APOE4 carriers go on to develop Alzheimer’s, but it would make sense if in some people, the memory part of the brain effectively becomes exhausted from overwork and this contributes to the disease,” added Christian Beckmann of Imperial College London, who was also involved with the study (press release again).
Coverage:
Is Alzheimer’s the result of a burnt-out brain? (New Scientist)
Young people could be screened for Alzheimer’s risk (Telegraph)
Alzheimer’s gene changes brain activity, study finds (Reuters)