Improving brain plasticity could delay the onset of Alzheimer's in elderly, says study.
The human brain loses 5 to 10 percent of its weight between the ages of 20 and 90 years old. While some cells are lost, the brain is equipped with two compensatory mechanisms: plasticity and redundancy.
"Brain plasticity refers to the brain's remarkable ability to change and reorganize itself. It was long thought that brain plasticity declined with age, however, our study demonstrates that this is not the case, even in the early stages of Alzheimer's disease," said principal author Sylvie Belleville at the Institut universitaire de geriatrie de Montreal.
The hypothesis behind the research was that certain cells traditionally involved in other brain processes could, through a simple memory-training program, temporarily take over since they themselves are not yet affected.
"Our research has validated our hypothesis. Not only were we able to use functional imaging to observe this diversification, but we also noted a 33 percent increase in the number of correct answers given during a post-training memory task by subjects with mild cognitive impairment (MCI) who, incidentally, are 10 times more likely to develop Alzheimer's disease," said Belleville.
The training program used was designed to help elderly subjects with MCI develop strategies, such as the use of mnemonics, for example, and promote encoding and retrieval, such as word lists, for example, using alternative areas of the brain.
"The hypothesis had already been raised, but our team was the first to provide scientific support, using a functional neuroimaging protocol," said Belleville.
The researchers worked with 30 elderly subjects - 15 healthy adults and 15 with MCI.
Magnetic resonance imaging was used to analyse brain activity in the two groups 6 weeks prior to memory training, one week prior to training and one week after training.
Before the memory training, magnetic resonance imaging in both the healthy elderly subjects and those with MCI showed activation in areas of the brain traditionally associated with memory.
As expected, decreased activation was observed in subjects with MCI. After training, brain areas in elderly subjects with MCI showed increased activation in areas typically associated with memory, but also in new areas of the brain usually associated with language processing, spatial and object memory and skill learning.
"Analysis of brain activity during encoding as measured before and after the training program, indicates that increased post-training activation in the right inferior parietal gyrus is associated with post-intervention improvement. The healthy area of the brain has taken over for the area that is compromised," said Belleville.
The study has been published in the online version of Brain: A Journal of Neurology.