A new study coming out of UC Davis Medical Center and the Center for Neuroscience shows how estrogen can protect brain cells against various insults that cause the mental deterioration seen in many ailments, including Alzheimer's disease. The study is among those specifically highlighted at Society for Neuroscience meeting in San Diego on November 14.
"We found, for the first time, that the hippocampus, a brain structure involved in memory, which shrinks in Alzheimer's disease patients, was larger in postmenopausal women who were taking estrogen replacement therapy than in either postmenopausal women who were not taking estrogen or a group of elderly men," says William Jagust, of the University of California in Davis. "Our results support the idea that estrogen replacement therapy protects brain cells and reduces the risk of developing Alzheimer's disease in postmenopausal women."
In the study the researchers examined the brains of 59 postmenopausal women and 38 elderly men. Some of the subjects had mild memory problems but none met the criteria for a diagnosis of Alzheimer's disease. The brain imaging technique, magnetic resonance imaging (MRI), which provides a three-dimensional picture of the living brain, determined the size of each subject's hippocampus. The hippocampus was larger in the women taking estrogen than in the women not taking estrogen and the men.
"These findings suggest that the protective effects of estrogen on the brain may be lost after menopause but could be maintained by estrogen replacement therapy," says Jagust.
Earlier MRI studies have found that the hippocampus is smaller in subjects with Alzheimer's disease than in normal elderly subjects, according to Jagust. A number of MRI studies also showed that elderly subjects with mild memory problems and a small hippocampus are more likely to develop Alzheimer's disease than subjects with memory problems who do not have a small hippocampus.
"This suggests that MRI measures of hippocampal size may be useful for identifying individuals who are at risk for developing Alzheimer's disease, as well as for monitoring the effects of various treatments and protective agents, such as estrogen replacement therapy," says Jagust.
In the future, the researchers plan to retest the memory of the subjects to determine if those subjects with a small hippocampus are more likely to show a decline in memory over time and whether estrogen replacement therapy helps to protect the other subjects against memory loss and the development of Alzheimer's disease.