Simply stated, people who have a mother diagnosed with Alzheimer’s are at a higher risk for developing the disease than someone whose father is afflicted.

The study included 49 cognitively normal people ranging between 50 and 80 years old. Of this group, 16 people had a mother with A.D., 8 had a father with A.D. and 25 had no family history of Alzheimer’s at all. All subjects underwent both neuropsychological and clinical tests, as well as positron emission tomography (PET) brain scans. This particular scan uses a technique to label glucose, otherwise known as the brain’s fuel, with a special chemical tracer.

Subjects with a maternal link to the disease had the largest reductions in glucose metabolism in many areas of the brain. The areas included the medial temporal lobes and posterior cingulate cortex. Both areas are involved with memory storage and retrieval. In the maternal link group, brain energy metabolism was lower by 25% in the posterior cingulate cortex.

The subjects both with either no family history of dementia or a paternal link to Alzheimer’s disease did not have any reductions in brain energy metabolism. Possible risk factors for A.D. including age, gender, education level and subjective memory complaints were accounted for. However, the effect in glucose metabolism among the subjects with a maternal link to Alzheimer’s remained significant.

This study is a first of it’s kind. While past studies show that people with A.D. have large reductions in brain energy in certain brain regions, this study dissects the family history of its subjects. It was after this dissection that medical professionals at New York University could prove that only individuals with a maternal link to Alzheimer’s disease have a reduced brain metabolism in the same regions of the brain as Alzheimer’s patients.

Researchers chose to study people with a family history of Alzheimer’s disease because it is a large risk factor for developing the disease. More than 5 million American’s suffer from Alzheimer’s. Individuals with an affected parent have a 4 to 10 fold higher risk compared to those with no family history of the disease. While it is not currently known why those with a family history are more likely to suffer from the disease, it is also unknown why those with a maternal link to Alzheimer’s disease are at a higher risk for developing it.

The study was published in the online edition of the Proceedings of the National Academy of Sciences during November of 2007.