NEW ORLEANS -- Two-thirds of those with late-onset Alzheimer's disease are women. And there is significant evidence that the loss of estrogen at menopause is bad for the brain and body metabolism.
Now research at Tulane is zeroing in on why estrogen can have an anti-aging effect on the brain.
Tulane scientists are working on something that could help our brains and our ability to remember.
"What we see is that rats that have a source of estrogen, will out perform rats that don't have a source of estrogen on a variety of memory tests," explained Dr. Jill Daniel.
Dr. Daniel, the Tulane associate professor of psychology and neuroscience, studies female rats to learn how hormone replacement, specifically the female sex hormone estrogen, for women after menopause can have an anti-aging effect on the brain.
And here's what they learned in their study. The rats that got estrogen only in their middle age and the rats that got estrogen from middle age through old age had better memories that lasted longer compared to the rats that got no estrogen.
"And they can remember if they have estrogen on board up to five or six hours where the food was hidden in the maze, whereas if they don't have estrogen, they usually forget after about 30 minutes or so," said Dr. Daniel.
The rats studied in the maze have no ovaries, so they produce no estrogen. They get a pellet implant, similar to what post menopausal women get, to deliver the estrogen to their blood streams. It is clear on imaging of the hippocampus, the part of the brain involved in memory and spatial navigation, that those on hormone replacement have more neurotransmitters and estrogen receptors.
In Alzheimer's disease, the hippocampus is one of the first places to show damage, memory problems and disorientation.
Now Dr. Daniel's lab has a $1.4 million grant from the National Institute on Aging to see why short term estrogen, just given in that critical window right after menopause in middle age, then taken away, continues to protect the brain.
"Our rats are now old and so they haven't seen hormones for several months, which is comparable to a couple of decades in a woman's life, and they are still out performing the rats who never had estrogen in middle age," she added.
Other studies also show that hormone replacement after menopause, can lower the risk and symptoms of dementia and Parkinson's disease.