Vitamins C and E seem to have a role in keeping the memory sharp. The active ingredient in evening primrose oil also apparently can help to keep at bay the kind of memory loss associated with advancing age.
An Irish research team has been examining the biochemical changes that take place in the brain. "We are particularly interested in trying to establish what happens in brain tissues when they age and what happens to the cognitive processes," said Dr Marina Lynch, of the Department of Physiology.
She and four doctoral students in her research group, Ms Aine Kelly, Mr Conor Maguire, Ms Emily Vereker and Mr Eamonn O'Donnell, travel to Los Angeles on Friday where they will present their research at the Society for Neuro-sciences conference.
The team was looking at aspects of brain biochemistry, she said, including how the membrane or outer surface of brain cells change with age. Subtle chemical alterations took place and these modified the way the cell functioned, Dr Lynch said. The object would be to understand the chemical changes and find a way to reverse them.
The hippocampus is a structure at the base of the brain which has been linked to the learning and memory processes, and Dr Lynch's research, conducted using rat models, focuses on cell changes in this structure.
One change relates to a fatty acid in the cell membrane called arachidonic acid. The chemical make-up of the fatty acid gradually alters as we age, from a polyunsaturated form to a saturated form, in turn disturbing the cell's ability to communicate.
The slow change to saturated fatty acid forms was thought to be caused by reactive oxygen, she said. These were oxygen-carrying chemical forms that could react with the body's own chemicals. In this case, the reactive oxygen attacks the polyunsaturated fatty acid, converting it to a saturated fatty acid.
Over time, more and more of the fatty acid can be converted by reactive oxygen, affecting the cell's ability to do its job properly. The level of cell change is measured in its "long-term potentiation" (LTP), which assesses how the cells respond to stimulation. The cell's LTP typically declined with age, Dr Lynch said, falling by as much as 50 per cent.
The team's response was to give the rats vitamins C and E, antioxidants to counteract the reactive oxygen. They found that the supplements helped block the chemical change and improved the cell's LPT. Dr Lynch also looked at the "precursor" from which arachidonic acid was formed, another fatty acid called gammalinolenic acid. This was the active ingredient in evening primrose oil, she said.
Then the rats were fed a diet enriched with evening primrose oil, the levels of polyunsaturated arachidonic acid were restored "and the LTP was restored" to near-normal levels in aged rats. The communication potential between cells was also improved.
"The data we have indicates to us that the gammalinolenic acid not just enhances the polyunsaturate level but also seems to exert some antioxidant effect," Dr Lynch said.
The ageing process was highly complex and was unlikely to be dependent on this one change, she said, but the findings were important, because they pointed towards a simple and inexpensive therapy that might help slow or delay the process as it relates to learning and memory.
Dr Lynch's team is also looking at how stress affected LTP. Her latest findings indicated that stress inhibited LTP and therefore learning and memory. In these trials, giving vitamin C and E supplements were again found to improve LPT despite stress.