Published on: February 13, 2013
by Stephen Adams for The Telegraph:
Taking hormone replacement therapy could delay the onset of Alzheimer’s for millions of women by slowing the ageing process, a study has suggested.
Researchers found that about one in five women carried a gene that made them more susceptible to dementia. It is believed that the gene — ApoE4 — speeds up the ageing process of DNA by up to four times, making people more likely to contract age-related illnesses. But HRT appears to protect the DNA and effectively slows down ageing.
Dr Natalie Rasgon of Stanford University School of Medicine in California, said: “This shows that [the gene] is contributing to ageing at the cellular level well before any outward symptoms of decline become apparent. “Yet oestrogen appears to have a protective effect for middle-aged women who are carrying this genetic risk factor.”
HRT is normally prescribed to menopausal women in their fifties to combat symptoms such as hot flushes and mood changes, although it also protects bones.
About one million women stopped taking HRT following a health scare in 2002 that suggested the treatment raised the risk of cancer. Doctors warn that using the treatment for long periods can increase the risk of breast cancer.
The drug has also been shown to cut heart attacks among women in their fifties.
The study, which involved 70 healthy women aged 45 to 65, did not follow them long enough to find out which ones developed Alzheimer’s. But over a two-year period it looked at changes in their cells that denoted ageing. The researchers looked for changes in the length of what are known as telomeres, which are repeated sequences of DNA that “cap” the end of chromosomes.
They act rather like the plastic caps on shoelaces — protecting genetic material from damage that can lead to age-related diseases, including cancer and Alzheimer’s. Telomeres shorten over the years, and scientists regard their length as a good measure of biological age.
The team took blood samples from the women and found that those not on HRT who carried the ApoE4 gene were six times as likely as non-carriers to undergo significant shortening of their telomeres. On average, the telomeres of carriers shortened by an amount equivalent to what might be expected to take 10 years.
But carriers of ApoE4 who did take HRT aged at a similar rate to those who did not have the gene.
HRT made no difference to the majority who did not carry the gene.
Emily Jacobs, of Harvard Medical School, who worked on the study, said it was well known “from numerous studies that ApoE4 is a major genetic risk factor for cognitive decline, Alzheimer’s disease and early mortality”.
Dr Simon Ridley, the head of research at Alzheimer’s Research UK, said the study could provide a useful new lead for research. “There is mixed evidence surrounding the effects of HRT on Alzheimer’s risk, and some research suggests the timing of HRT may be important. We’d need to see large-scale, long-term trials to know whether HRT can prevent Alzheimer’s.”
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