A comment on the article --
"A Molecular Signature of Cognitive Decline", by Greg Miller in Science.
The article discusses research by André Fischer (et al) reversing some measures of cognitive decline in mice involving histone protein H4K12.
Because of it's connection to autism I've been generally following the research on the powerful histone deacetylase (HDAC) inhibitor valproic acid (VPA) for awhile. It operates on histone 1. The article appears to be about the histone 4. It is interesting to compare the two wiki's on histone 4 and VPA. The wiki on VPA is very long, the wiki on histone 4 is almost zip. Anyway, I don't recall where specifically but on the longevity research lists over the years there has been a general skepticism toward crude shot-gun approaches to methylation and histone strategies where the logic seems to be that aging involves both inappropriate under-expression of genes as well as inappropriate over-expression of genes. -- Kind of like individual cells are forgetting what exactly is the role they are supposed to be playing in the organism. If that thinking is correct, then the article is talking about a process that may possibly accelerate general aging processes. To the credit of the scientist and the journalist, the article mentions that Arancio "...cautions that it remains to be seen whether they are specific enough to work as memory enhancers without causing serious side effects."