The hormone estrogen is important in keeping the brain healthy and allowing memories to form, but its effects lessen as women age. A team of researchers from the University of Florida is looking to improve the situation, testing a gene therapy method to return memory function in laboratory rats.

Estrogen plays a big role in the brain, helping to maintain the organ's ability to form and maintain connections (something known as "plasticity") which in turn facilitates the process of learning and retaining memories. Lowered estrogen levels can lead to a loss of brain plasticity, causing patients to have problems with memory.

As women get older, the amount of estrogen in their bodies drops significantly, in a transition period known as menopause. From the onset of menopause, which usually begins in the early 50s, hormone replacement therapy is effective in protecting the brain against damage, including neurodegenerative conditions such as Alzheimer's disease, up until around age 65. However, after that point, the technique stops being effective.

The University of Florida team turned to gene therapy in an attempt to tackle the issue, increasing the expression of two estrogen receptors in the hippocampus – a part of the brain that's central to forming and maintaining memories.

They conducted tests on a large sample of aging laboratory rats, with 72 animals split into two sets of three groups – one for each overexpressed receptor and one control group. One set of groups was tested with the gene therapy treatment alone, while another set received estrogen alongside the therapy. Of the six groups, significant improvements in memory were observed in the memories of one of the receptor plus estrogen groups, referred to as the alpha receptor group.

While only an early step, the study marks an important breakthrough in the development of alternatives to hormone replacement treatments.

"In the short term, this finding helps us understand how estrogen rescues memory and keeps the brain young and plastic," says team member Professor Thomas Foster. "In the long term, this finding may eventually allow us to bypass estrogen and target the receptor or brain plasticity mechanisms directly."

The researchers plan to continue their work, looking to better understand and ultimately harness the power of the alpha receptor. In the meantime, they published their findings in The Journal of Neuroscience.