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Sperm quality may decline as men age

10 June 2006
Appeared in BioNews 362

A new study, published in the Proceedings of the National Academy of Sciences, has found that sperm quality may deteriorate as men age. The study, which involves a relatively small number of volunteer subjects, was conducted at the Lawrence Livermore National Laboratory in California. Ninety-seven healthy, non-smoking men were recruited from the current workforce at the laboratory and those that had retired, with an age range of 22 to 80. Those enrolled into the study were approximately evenly divided by decade so changes in sperm genetic quality could be compared over time.

Sperm samples were collected from the volunteers over a two-month period and were required to be delivered to the laboratory within two hours of ejaculation. The samples were then examined using a technique called flow cytometry. This approach allowed the researchers to study the quality of sperm DNA, in addition to the usual male fertility indicators of sperm quantity, shape and motility. The team found that sperm numbers and motility were unchanged across the group, but they did detect changes in DNA quality that could indicate a possible deterioration linked to increasing age. Unlike eggs, which are produced before birth and age with the woman, sperm are continuously produced from sexual maturity through to old age. This had been thought to protect men from the kind of risks associated with older mothers.

In this study the researchers show that while men do not seem to have an increased risk of Down syndrome, commonly associated with older mothers, there may be greater risk of passing on other genetic disorders. As the men aged, the team found that the number of genetic mutations that can lead to achondroplasia (a common form of dwarfism) increased at a rate of about two per cent per year. Compared to the younger men, the oldest volunteers had five times as many sperm showing some DNA fragmentation, which can be associated with both genetic anomalies in the offspring and infertility. Although the general trend toward increasing deterioration with age was clear, there were disparities in each age group, with some men in the oldest bracket showing few mutations and some in the lower cohorts with many.

Brenda Eskenazi, an epidemiologist at Berkeley University and co-lead investigator of the study commented, 'We know that women have a biological time clock. Our research suggests that men too have a biological time clock - only it is different. Men seem to have a gradual rather than an abrupt change in fertility and in the potential to produce viable healthy offspring'. She added, 'Men need to consider not just the female's fertility, but their own, and not just their fertility but their ability to produce healthy offspring'.

Older sperm produce more dwarves
The Register |  6 June 2006
Research finds sperm quality drops, genetic problems rise as men age
San Francisco Chronicle |  6 June 2006
Senior sperm have dodgier DNA
Nature News |  5 June 2006
Sperm quality may decline as men age |  7 June 2006
7 July 2008 - by Ailsa Stevens 
BioNews reporting from ESHRE conference, Barcelona:By Ailsa Taylor: Scientists have found further evidence to suggest that, like women, fertility drops in men as they age, heard delegates at the annual meeting of the European Society of Human Reproduction and Embryology. The research, led by Dr Stephanie Belloc of the...
4 December 2006 - by Dr Laura Bell 
A new study presented this week at the Radiological Society of North America conference in Chicago showed that a minimally invasive surgical procedure may help restore male fertility. Some experts believe that male infertility is commonly caused by the formation of varicose veins in the testicle...
25 July 2005 - by Professor Allan Pacey 
The eighth child of Charlie Chaplin was born when he was 73 and as far as we know has lived a healthy life. However, whilst most men remain fertile into their old age, it has long been recognised that to father children later in life increases the risk of their...
21 July 2005 - by BioNews 
The risk of having a child born with certain congenital problems may increase with the father's age, US and Danish researchers say. In a study of over 70,000 births, published online in the journal Human Reproduction, they report that the risk of Down syndrome and other conditions begins to increase...
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