Junk food worsens memory

Unhealthy food impairs long-term spatial memory

Polina Gershberg, Naked Science

Scientists from the University of New South Wales investigated the effect of foods high in fat and sugar (for example, cakes, cookies and chips) on the cognitive functions of rats. An article with the results of the work was published in the journal Scientific Reports (Pattern of access to cafeteria-style diet determines fat mass and degree of spatial memory impediments in rats).

In the experiment, the rats were divided into 4 groups. The researchers gave three of them unhealthy food for six weeks. Rats from the first group consumed junk food for three days in a row during the week, after which they sat on a healthy diet for four days. For rodents from the second group, these intervals were 5 and 2 days, respectively, and the third group ate harmful foods throughout the experiment. The latter group acted as a control group and ate only healthy food.

The animals underwent two series of tests for the ability to remember objects and their locations – on the 16-18 and 23-25 days of an unhealthy "diet". The memory check took place in a special box – a box made of black acrylic measuring 60x60x60 centimeters, the floor of which was marked into four squares. At first, the rats were accustomed to an empty box, letting them inside for 10 minutes for two days in a row. After that, the rodents were put into a box for 5 minutes, where two objects were placed in certain places – they could be ceramic mugs or aluminum cans.

After the animal had studied the situation, it was removed from the box for five minutes; during this time, the objects and the pad were wiped with ethanol, and then either one of the objects was replaced or moved to another square. After these procedures, the rat was returned to the box for three minutes.

Spatial memory was evaluated using the recognition index. This parameter was calculated as the time spent exploring a new or relocated object, correlated to the time spent exploring both objects in the test box. Lower values of this parameter indicated a deterioration in the quality of recognition.

According to research data, depending on the frequency of access to junk food, spatial memory deteriorated in animals to one degree or another. The more days in a row the rat ate unhealthy foods, the worse it reproduced spatial information.

"We all know that a healthy diet with a minimum amount of harmful foods is good for our overall health and performance, but this article shows that it (a healthy diet – ed.) is also important for optimal brain function," says Margaret Morris, lead author of the study. Earlier, under the leadership of Morris, work had already been carried out that demonstrated the changes that occur under the influence of unhealthy diet in the hippocampus of rats. This part of the brain plays an important role in spatial orientation and navigation.

Portal "Eternal youth" http://vechnayamolodost.ru