NY Times – In the largest collaborative study of the brain to date, scientists using imaging technology at more than 100 centers worldwide have for the first time zeroed in on genes that they agree play a role in intelligence and memory.
Scientists working to understand the biology of brain function — and especially those using brain imaging, a blunt tool — have been badly stalled. But the new work, involving more than 200 scientists, lays out a strategy for breaking the logjam
In summary, we detected four genetic loci associated with hippocampal volume in a large, population-based, dementia-free sample. Two of these loci replicated in independent community-based samples, as well as in a mixed-age sample from the ENIGMA Consortium that included some participants with cognitive impairment, indicating that these loci may have broad implications for determining the integrity of the hippocampus across a range of ages and cognitive capacities. Findings from this study identified a series of relevant and potentially important genes associated with hippocampal volume during development and aging and in the presence of Alzheimer’s disease. Exploration of these genomic regions in dense-genotyping, expression and translational studies will be required to understand the role of these genes in determining hippocampal volume.
In a separate analysis in Australia, Dr. Martin and Dr. Wright found that size correlated with I.Q. People with the larger brains scored slightly higher on a standardized test. The results are all averages, meaning that they hold for the group but say nothing about any individual. (Some very smart people have relatively small brains.)
The collaborators also found that about 10 percent of people carried a gene variant that correlated with a slightly accelerated rate of atrophy in the hippocampus. The hippocampi — there are two, each deep in the brain, one in the right side and one in the left, about level with the ears — are needed to form new memories. People with dementia often show pronounced atrophy in this region. The study was not set up to find a link between the gene variant and dementia, but experts suspect a connection.
Other meta-analysis of genome