Behind the Headlines

Tuesday April 28 2009

The study used memory tests on rats to look at memory retention

“Students revising for exams and patients with brain disorders such as Alzheimer's disease” could be helped by a pill that could make memories ‘stick’, The Daily Telegraph reported. It said that scientists who have been researching obesity found that a chemical released in the body when fats are eaten “improved memory retention in two different tests” in rats. The newspaper said they now hope to develop drugs that “mimic the effect of fat rich foods in order to boost memory”.

This research is at a very early stage. Although injecting healthy rats and mice with this chemical improved their performance in memory tests, further studies are needed to determine whether the chemical plays a similar role in humans. Based on this research alone, it is too early to say whether OEA or related drugs would have any affect on people with dementia or those studying for exams.

Where did the story come from?

Dr Patrizia Campolongo and colleagues from the University of California and research centres in Italy carried out this research. The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the Agilent Foundation, the National Institute on Mental Health and Ministero Istruzione Università e Ricerca in Italy.

The study was published in the peer-reviewed scientific journal, Proceedings of the National Academy of Sciences of the USA.

What kind of scientific study was this?

This animal study investigated what affect a chemical that is released during feeding had on the performance of rats in two memory tests. The chemical, Oleoylethanolamide (OEA), is released in the body when fats in the diet enter the small intestine. It is known that one of the effects or functions of OEA is to produce a sensation of being full.

The researchers say that there would be a clear evolutionary advantage for animals in being able to remember contextual information about food they found, such as the exact location and how safe it was to get. They wanted to see whether the OEA mechanism might have helped the ancestors of today’s animals to remember where to find safe access to sources of fatty food.

The researchers used two different memory tests in their experiments. One involved the rats being trained to associate entering a darkened compartment with an unpleasant stimulus (an electric shock). The other involved them being trained to swim around a tank and find submerged platforms to escape the tank (water maze). After the training, the researchers measured how long the rats avoided entering the darkened compartment and how long it took them to locate the submerged platforms in the water tank.

The researchers injected some of the rats with OEA either before training or at different times after training (immediately or three hours after), and looked at whether the rats performed differently in the memory tests to rats that had not been injected with OEA. They also explored which parts of the brain might be involved in these processes by injecting different drugs to block activity in different areas of the brain.

Because OEA affects the sensation of fullness by activating a protein called PPAR-α, the researchers also looked at whether this pathway affected memory. They did this by determining whether OEA had an effect on memory in mice that had been genetically engineered to lack PPAR-α.

What were the results of the study?

The researchers found that rats injected with OEA immediately after training had an improved performance in the memory tests. Injecting the rats before training had a moderate effect, but injecting them three hours after training had no effect.

They found that blocking activity in areas of the brain called the nucleus tractus solitarii and the basolateral complex of the amygdala stopped OEA from having an effect on memory. These areas are parts of the brain deep within the temporal lobes, are known to be involved in processing memories. The researchers also found that mice genetically engineered to lack the protein PPAR-α did not have improved memory in response to pre-training OEA injections, although normal mice did.

What interpretations did the researchers draw from these results?

The researchers concluded that OEA can improve memory consolidation and suggested “pharmacological strategies aimed at mimicking or amplifying OEA signalling... might offer new opportunities for therapeutic intervention in cognitive disorders”.

What does the NHS Knowledge Service make of this study?

This study gives researchers an idea of the potential role of OEA in consolidating memories in mammals. However, the research is at a very early stage. Although the chemical improved healthy rats’ performance on a number of memory tests, further studies are needed to determine whether the chemical plays a similar role in humans, and whether it has any affect on people with cognitive disorders such as dementia.

In addition, as the OEA was injected in this study, it is not possible to say whether increasing intake of fatty foods would have any effect on memory.

Analysis by Bazian

Edited by NHS Choices

Links to the headlines

Memory pill that could help students and Alzheimer's patients being developed. The Daily Telegraph, April 28 2009

Fatty foods 'offer memory boost' . BBC online, April 28 2009

Links to the science

Campolongo P, Roozendaal B, Trezza V et al. Fat-induced satiety factor oleoylethanolamide enhances memory consolidation. PNAS 2009; Published online before print April 27

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