A study by the School of Medicine at the University of Kansas showed that individuals who have a mother with Alzheimer’s carry a greater risk of developing the disease than those with a father who has the disease or now family history of the disease whatsoever.

The study examined 10 adults who had a mother with Alzheimer’s and 11 adults who had a father with the disease. There were also 32 people who had parents that did not have Alzheimer’s. All participants were in the age range of 63 to 83 and were healthy and cognitively able when the study began.

Through a number of memory tests and brain scans, the researchers found no difference in the participants with a father with Alzheimer’s and those with no family history of Alzheimer’s. However, those who had a mother with the disease experienced 1.5 times more brain shrinkage each year during the two-year study. Shrinkage happened especially in the areas surrounding episodic memory and memory retrieval.

Researchers predict the cause for this phenomenon may be due to a link on the mitochondrial DNA, which passes only from the mother to the child. However, further research is needed before any final conclusions can be made. A spokeswoman from the Alzheimer’s Association reviewed the findings and stated that a sample size of only 53 individuals was too few to draw conclusions from.