The decision to prematurely undergo an oophorectomy (ovary removal) and hysterectomy (uterus removal) could have unintended consequences. A new study found that these procedures can cause a drop in body estrogen levels that could increase risk of Alzheimer's.

The study was performed on rats that had experienced surgical menopause after the removal of the estrogen-producing ovaries. Surgical menopause is a phrase to describe what will naturally occur in women who have undergone oopherectomy, and involves many of the same symptoms of "natural" menopause. The goal of the study was to find out whether surgical procedures that cause surgical menopause could increase a woman's risk for other diseases.

The rats in the study were monitored for 10 weeks following the surgery and split into two groups: one half was given hormone replacement therapy and the other half was not.

In order to test the differences between the two groups, the researchers induced a stroke in some of the test rats. The results showed that the rats that received no hormone therapy suffered more brain damage in a region that was normally resistant to strokes called CA3, found in the hippocampus and involved in memory. These rats later produced proteins associated with Alzheimer's in the CA3 region. The proteins continued to multiply excessively and began destroying brain cells.

"We wanted to find out why that is occurring," said Darrell Brann, co-author and professor at the Institute of Molecular Medicine and Genetics at Georgia Regents University. "We suspect it's due to the premature loss of estrogen."

Previous studies from Harvard researchers support the argument, finding that surgical menopause at an earlier age leads to declining memory and critical thinking skills.

The study was published in Brain journal, led by researchers from the Medical College of Georgia at Georgia Regents University.