In the past, there have been reports that women who have had a hysterectomy (i.e. removal of the uterus) prior to the onset of menopause have an increased risk of dementia. However, little was known about why such a risk would be increased in them. To find out what the link between removal of the uterus and memory problems would be, the Americans at the aforementioned centre decided to investigate.

The scientists conducted their research on rats. They divided the rodents into four groups:

• in the first, the animals had only their ovaries removed,
• in the second, the rats had the uterus alone removed,
• in the third group, animals had both the uterus and ovaries resected,
• in the last group, the control group, 'sham' operations were carried out, where no reproductive organs were removed from the rodents.

Six weeks after the surgeries, all rats were placed in a prepared maze - the rodents were expected to master ways to exit the maze. Later, certain elements of the maze were modified to test the spatial memory function of these animals.

Rats from different groups had different difficulties in negotiating the maze, but it turned out that the greatest challenge was experienced by those that had undergone a hysterectomy. One of the reasons for this was that when the levels of various sex hormones were compared in the group of animals that had had their uterus removed and those in the control group, there were then extremely significant differences in the levels of these substances between the groups.

What the ultimate link between the uterus and memory is - this is still ultimately unknown. However, the American study suggests that this organ may play a role in more than just reproductive processes.