High-fat diets impair memory
Neural stem cells (NSCs) constantly replenish adult brains with new nerve cells called neurons. These are especially important in areas of the brain like the hippocampus, which is responsible for memory. NSC activity is heavily influenced by environmental factors like stress, disease and diet. Since diet-induced obesity has been linked to poor performance in cognitive tests involving memory, scientists working on the EU-funded OBINNSC1 (The physiological control of stem cells: Obesity, insulin, and neural stem cell dynamics) project wanted to see whether high-fat diets affect neuron development in the adult hippocampus. Researchers fed mice a high-fat diet for 16 weeks, at which point the mice became obese and developed insulin resistance, a precursor to diabetes. Researchers looked at the number of neurons produced from NSCs at various time points during the experiment. They found that, at first, the high-fat mice produced new neurons at a faster rate than mice fed a normal diet. By the end of the 16 weeks however, neuron production was reduced by around 20 % in the now obese mice. This suggests that before becoming obese, a fat-induced increase in neuron production exhausted stem cell supplies. By the time the mice became obese, neuron production and associated cognitive abilities had slowed. Researchers next wanted to see whether neuron production was affected by the high-fat diet itself or by fat tissues in obese mice. To do this they tested mice strains that do not become obese from eating dietary fat. Preliminary results indicate that eating a high-fat diet, and not developing obesity, is enough to impair neuron production and brain function. OBINNSC1's discovery that dietary fats adversely affect stem cell dynamics independently of weight gain highlights the importance of a well-balanced diet. Their finding that the food choices we make can directly impact brain function has far-reaching implications for the 3.75 million obese children in Europe.
Keywords
High-fat diets, memory, obesity, neuron production, neural stem cells
