CHILDREN born to older fathers have a higher risk of eventually developing Alzheimer's disease, according to a new retrospective study.
Older mothers are more likely to give birth to babies with Down's syndrome, and people with Down's develop Alzheimer's disease earlier and more often than others. Intrigued by the association between these diseases, Lars Bertram of the Technical University of Munich and his colleagues wondered if parental age also plays a more direct role in Alzheimer's.
The researchers studied 206 patients with Alzheimer's disease. Susceptibility to the disease is associated with certain major genes, so their first step was to try to establish each person's inherited risk. To do this they found out the incidence of Alzheimer's in each patient's family.
Then they looked at the groups of patients at each extreme-comparing those least likely to have the disease genes with those most likely to have them-hoping to find an extra risk factor among the first group to explain why they had Alzheimer's.
Those patients who were least likely to have inherited a major disease gene had fathers who were significantly older than fathers of the second group and fathers of people of the same age who did not have Alzheimer's, the researchers report in the current issue of the journal Neurogenetics (vol 1, p 277).
Fathers of this low-probability group had been on average 35á7 years old when their child was born, whereas the fathers of patients who were most likely to have a major disease gene had only been 31á3 years old at the birth of their child.
As people age, researchers suspect, damage builds up in their DNA and gets passed on to the child. "There's an accumulation of environmental factors which somehow alter the genome of the father," says Bertram.
"Their finding is extremely interesting,"says Simon Lovestone, an Alzheimer's disease specialist at the Institute of Psychiatry in London.
Author: Alison Motluk
NEW SCIENTIST issue 19th September 1998
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