[tt] NS: Longevity gene keeps the brain ticking over

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This is no surprise.

Longevity gene keeps the brain ticking over
http://www.newscientist.com/article.ns?id=mg19826604.100&print=true
18 June 2008
Andy Coghlan

A GENE linked to IQ might also help to prolong life.

The gene codes for an enzyme called succinic semialdehyde
dehydrogenase (SSADH), which destroys GABA, a neurotransmitter that
dampens brain activity and causes drowsiness. The gene comes in two
common forms: the so-called "T" version is 20 per cent less
efficient than the "C" version. In previous studies, young people
with two copies of the T version performed slightly worse on IQ
tests.

SSADH also detoxifies the brain by getting rid of excess acid,
helping to protect cells from the free-radical damage that
accelerates ageing.

So to study the effects of the gene on ageing and longevity,
Giuseppe Passarino of the University of Calabria, Italy, and his
colleagues took a representative sample of 514 Italians aged between
18 and 107 and identified which gene variants they carried. Of these
they also evaluated 115 people aged 65 to 85 using a standard test
of cognitive ability. As expected, those with two copies of the T
version of the gene performed significantly worse on tests.

The team then used the ages and gene information to reconstruct a
survival "snapshot" for the entire group. Their model showed that
people carrying two Ts were unlikely to live past the age of 85; the
maximum age for those carrying at least one C copy was approximately
100 years (Annals of Human Genetics, DOI:
10.1111/j.1469-1890.2008.00450.x).

While those carrying two copies of the T gene certainly do decline
faster in old age, it is not an early death sentence, Passarino
says. "There's no doubt that lifestyle, such as reading, having
challenging work and enriching your cultural life, is far more
important than having the bad variant," he says.

"The two associations taken together tell a good story," says Robert
Plomin of the Institute of Psychiatry in London, who discovered the
cognitive effects of the SSADH gene in 2004. "Although the sample
size is small, with only 115 taking the test compared with the
thousands expected in today's studies, the reported associations
with cognitive ability are significant and in line with our previous
results," he says.

Plomin is less sure about the association with longevity because of
the complicated estimation method used by the researchers. "But
there are so many large studies of ageing populations that we'll
soon know whether the T version is more frequent in short-lived
people," he says.

The Human Brain - With one hundred billion nerve cells, the
complexity is mind-boggling. Learn more in our cutting edge special
report.

Genetics - Keep up with the pace in our continually updated special
report.

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Weblinks

Giuseppe Passarino, Calabria University, recent papers
http://lib.bioinfo.pl/auth:Passarino,G
Robert Plomin, Institute of Psychiatry
http://www.robertplomin.com/
The GenAge Database
http://genomics.senescence.info/genes/