A retrospective investigation of 206 people who have the degenerative illness, but no history of it occurring in the family, revealed a statistically significant link with the age of their father when they were born.
Some genes are known to contibute to the chance of developing Alzheimer's, but the new study, carried out by Lars Bertram at the Technical University of Munich, suggests that simply having an older father - average age 35.7 - can be a risk factor even in the absence of those genes. For those where there was a family history of Alzheimer's, the average age of the father was 31.3 years.
Though the sample is comparatively small, it is in line with the knowledge that ageing is associated with genetic damage to the sperm, which carry the father's genetic contribution to the child. That might eventually lead to Alzheimer's in the offspring. "There's an accumulation of environmental factors which somehow alter the genome of the father," Dr Bertram told New Scientist magazine.
Similar effects are already known to occur in women, where mothers over 35 have a far higher chance of giving birth to babies with Down's syndrome, which is caused by a genetic defect in the embryo. People with Down's syndrome are also more likely eventually to develop Alzheimer's.Reuse content