A gene that breaks down degrade catecholamines such as dopamine, epinephrine, and norepinephrine (all neurotransmitters) has variants that influence brain aging and brain performance. The variants come with trade-offs.
For the study, researchers followed 2,858 African-American and Caucasian people between the ages of 70 and 79 for eight years. Participants’ DNA was analyzed for the catechol-O-methyltransferase (COMT) gene, a gene shown in studies to affect thinking skills. The allelic variants associated with this gene are the Val and Met variants.
The group was also given two types of thinking tests. One test measured skills such as language, concentration and memory. The other test measured response time, attention and judging sights and objects.
The study found that the Met variant of the COMT gene was linked to a greater decline in thinking skills over the years, while the Val variant had a protective effect on thinking skills, with lower declines over the years. In Caucasians, those with the Val variant scored 33 percent better over time than those without the variant. Among African-Americans, people with the Val allele gene variant scored 45 percent better over time than those who did not have the variant.
Slower aging makes the Val variant sound appealing, right? But the Met variant seems better at younger ages. So then is the Val variant keeping the brain younger longer by lowering brain performance at earlier stages in life?
“This finding is interesting because in younger people, the Val genotype has been shown to have a detrimental effect,” Fiocco said. “But in our study of older people, the reverse was true. Finding connections between this gene, its variants and cognitive function may help scientists find new treatments for the prevention of cognitive decline.” Fiocco added, however, that the results need to be replicated by others before the field can be confident that the Met variant of the COMT gene plays a role in late life cognitive decline.
These results underscore the trade-offs in genetic variants. Beneficial mutations often don't just boost functions. They provide benefits at a cost. Whether the benefits outweighed the costs in the past does not determine whether the benefits outweigh the costs today. Many humans have mutations (e.g. sickle cell anemia and beta thalassemia against malaria) that beneficial in the past but only harmful in their present circumstances. Still other genetic variants of other genes still provide both benefits and costs today.
|Share |||Randall Parker, 2010 April 21 11:21 PM Aging Brain Genetic Studies|