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A new study has found that male DNA can be commonly found in the brains of women, most likely derived from prior pregnancy with a male fetus.

The study, conducted at Fred Hutchinson Cancer Research Center, is the first of its kind.

Although it is not clear as to what are the medical implications of male DNA and male cells in the brain, other studied on microchimerism (presence of a small number of cells that originate from the fetus and are therefore genetically distinct from the cells of the mother) have linked it to autoimmune diseases and cancer, sometimes for better and other times for worse, Medical Xpress reports.

According to lead author William F. N. Chan, Ph.D., in the Department of Biochemistry at the University of Alberta, the current study is the first description of male microchimerism in the female human brain. Before this study, it was not known that microchimerism was relatively common and that these cells could cross the blood-barrier in humans.

For the research, scientists examined the brain specimens from 59 women who died between the ages of 32 and 101. The researchers found that male microchimerism was present in 63 percent of the subjects and was distributed in different brain regions.

They also found that perhaps the presence of the cells was persistent throughout the human lifespan and the oldest woman whose brain was detected with the male fetal DNA was 94-years-old.

Other revelations of the study were that 26 of the women had no neurological disease while 33 did have Alzheimer's. It was found that women who had Alzheimer's somehow had a lower prevalence of male microchimerism. Specifically, the concentrations were lower in the areas of the brain which was affected by Alzheimer's.

However, in spite of these findings the authors say that they could establish a link between Alzheimer's disease and level of male cells of fetal origin due to the small number of subjects and largely unknown pregnancy history of the women.

Also, the authors say that this study does not establish an association between male microchimerism in the female brain and relative health disease.

"Currently, the biological significance of harboring male DNA and male cells in the human brain requires further investigation," Chan said.

However, some other studies linked male microchimerism to impact a woman's risk of developing some types of cancer and autoimmune disease. The study findings were published Sept. 26 in PLOS ONE.