Alzheimer's can be predicted by young adults brain activity

Scientists from the University of Oxford and Imperial College London did a new brain imaging study, and they found that young adults show changes in their brain activity decades before any symptoms appear. This study may provide clues as to why certain people develop Alzheimer's, and it could lead to a diagnostic test that will identify individuals at risk at an early age.

About a quarter of the population has the APOE4 genetic variant. Most carriers of this variant will not develop Alzheimer's, but people who inherit one copy of APOE4 have up to four times the normal risk of developing the late-onset variety of the disease. People who have two copies have around ten times the normal risk.

Previous studies have shown that elderly healthy carriers of APOE4 have differences in their hippocampus, the region of the brain involved in memory. However, this new study is the first to show hyperactivity in the hippocampus of healthy young carriers. It also showed that their brains behave differently even at rest.

The study used functional Magnetic Resonance Imaging (fMRI) to compare the brain activity of 36 volunteers, aged 20 to 35, with 18 carrying at least one copy of the APOE4 gene and 18 non-carriers acting as controls. They all performed normally on cognitive skills tests.

The researchers looked at how their brains behaved while they were resting and also while they were doing a memory-related task. Even at rest, the carriers and non-carriers each had distinct patterns of brain activity. These results support the idea that the memory function of the brain can wear itself out.

Dr. Christian Beckmann, from the Division of Neurosciences and Mental Health at Imperial College London, said: "Our brains are always active - our minds wander even when we're not carrying out specific tasks. We were surprised to see that even when the volunteers carrying APOE4 weren't being asked to do anything, you could see the memory part of the brain working harder than it was in the other volunteers. 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. This theory is supported by studies that have found the opposite pattern in people who have developed Alzheimer's, with these people showing less activity than normal in the memory part of the brain."

The researchers are going to do a similar study of patients with mild cognitive impairment, to see how these differences in young people's brain activity are associated with later changes.

Source: "Young Adults At Future Risk Of Alzheimer's Have Different Brain Activity, Says Study." ScienceDaily. 14 Apr 2009.