Gene could explain why Alzheimer's is more common in women than men

A gene has been discovered which may explain why women are more likely to get Alzheimer’s than men.

A study identified that a gene called MGMT is linked to a 44 per cent increased risk of women developing the condition but there was no such link between the gene and men suffering from Alzheimer’s.

Nearly two-thirds of patients living with dementia are women, and the reason behind this has eluded scientists for decades. It is the biggest killer of women in the UK with one in eight women dying of the condition. Around one in ten men die of the disease.

MGMT is involved in repairing damage done to DNA but also fuels the production of amyloid beta and tau, the rogue proteins that cause Alzheimer's.

Link remains unknown

Around six per cent of the population have the MGMT gene and exactly how it is linked to increased risk of Alzheimer’s remains unknown.

“This is one of a few and perhaps the strongest associations of a genetic risk factor for Alzheimer’s that is specific to women,” said Dr Lindsay Farrer, the study senior author and chief of biomedical genetics at the Boston University School of Medicine.

She told The Telegraph that the faulty MGMT gene “confers an increased risk of 44 per cent” among women who lack the APOE-E4 variant which has previously been linked to increased Alzheimer’s risk.

But she warned that the figure could be anywhere between 24 and 64 per cent, and urged caution when interpreting the results.

Likely overestimate of true risk

The figure is likely an overestimate of the true risk as the participants in the study were selected from specialty memory clinics.

“A robust estimate of risk will require confirmation in other large samples of Alzheimer cases and controls,” she said.

The study looked at DNA variations in a large extended family of Hutterites - a founder population of central European ancestry who settled in the American midwest 150 years ago.

They are often analysed for genetic determinants of disease because they have a relatively small gene pool due to their isolated, insular culture.

Dr Farrer and colleagues also looked at another set of genetic data on 10,340 women across the country who lacked the APOE ε4 mutation linked to Alzheimer's.

In both groups, MGMT was significantly associated with developing Alzheimer's.

The results are published in Alzheimer's Disease & Dementia: The Journal of the Alzheimer's Association.