Dietary Fats Found to Induce Long-Term Memory Formation

Researchers have discovered that eating fat-rich foods triggers the formation of long-term memories of that activity. This new study adds to recent research linking dietary fats to appetite control and may help to provide new approaches for treating obesity and other eating disorders.

The study findings appear in May 1, 2009, in the early online edition of the Proceedings of the [U.S.] National Academy of Sciences (PNAS). Dr. Daniele Piomelli, the Louise Turner Arnold chair in neurosciences at University of California, Irvine (UCI; USA), partnered with UCI's Dr. James McGaugh, one of the world's leading learning and memory researchers, to study how dietary fats facilitate memory retention.

Dr. Piomelli's earlier research identified how oleic acids from fats are converted into a compound called oleoylethanolamide (OEA) in the upper region of the small intestine. OEA sends hunger-curbing messages to the brain to increase feelings of fullness. In elevated levels, OEA can reduce appetite, produce weight loss, and lower blood cholesterol and triglyceride levels.

Drs. Piomelli and McGaugh discovered that OEA also causes memory consolidation, the process by which superficial, short-term memories are transformed into significant, long-term ones. It does that, Dr. Piomelli noted, by activating memory-enhancing signals in the amygdala, part of the brain involved in the consolidation of memories of emotional events.

The researchers found that administering OEA to lab rodents improved memory retention in two different experiments. When cell receptors activated by OEA were blocked, memory retention effects decreased. "OEA is part of the molecular glue that makes memories stick,” Dr. Piomelli said. "By helping mammals remember where and when they have eaten a fatty meal, OEA's memory-enhancing activity seems to have been an important evolutionary tool for early humans and other mammals.”

Dietary fats are important for basic health, helping with the absorption of vitamins and the protection of vital organs. While the human diet is now rich in fats, this was not the case for early humans. In fact, fat-rich foods in nature are quite rare. "Remembering the location and context of a fatty meal was probably an important survival mechanism for early humans,” Dr. Piomelli said. "It makes sense that mammals have this capability.”

In the present day, Dr. Piomelli noted, such memory enhancement may not be so beneficial. While OEA contributes to feelings of fullness after a meal, it could also engender long-term cravings for fatty foods that, when eaten in excess, can cause obesity. Currently, according to Dr. Piomelli, compounds that mimic OEA are in clinical trials for triglyceride control. He is interested in learning whether they could improve consolidation in people with memory problems.

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