Scientists, for the first time, have found that the variation in a gene, responsible for the production of a protein called neuroglobin, is linked with an increased risk of Alzheimer's Disease (AD).
For the study, researchers at the McKusick-Nathans Institute of Genetic Medicine of the Johns Hopkins University School of Medicine analysed the genetic neighbourhood of neuroglobin.
The team found that individuals with genetic variations linked with less neuroglobin production had an increased risk for AD.
"An intriguing part of this study was the high levels of neuroglobin that we found in the Alzheimer's brain, which was exactly the opposite from what we expected," said Dr. Dimitrios Avramopoulos, an associate professor in Hopkins' Institute of Genetic Medicine and the Department of Psychiatry.
The researchers measured levels of gene product in 56 different samples of human brain tissue-30 from confirmed cases of Alzheimer's and 26 without brain disease.
They found that neuroglobin levels decreased with advancing age, which was consistent with risk of Alzheimer's increasing with advancing age.
They also observed that levels of neuroglobin were lower in women than in men, suggesting that women had a slightly higher risk of Alzheimer's.
And, surprisingly, neuroglobin levels were higher in the brain tissue from Alzheimer's patients than that of the control group.
Earlier studies highlighted a protective function for neuroglobin and showed that mouse brains respond to stress, which in this case is a lack of oxygen, by producing more neuroglobin.
Avramopoulos explained: "The older we get, the less neuroglobin this particular gene produces in our brains, unless something stimulates the gene to produce more. That something could be a stressor such as a lack of oxygen resulting from stoke or emphysema, for instance. And it looks like it also could be Alzheimer's disease. Further work on this gene will likely provide intervention targets for a multitude of very common conditions including Alzheimer's."
The study has been published in Neurobiology of Aging.