How environmental factors could provide for a young brain

A stimulating environment keeps the “hippocampus”—which is the brain's main memory control center—"young,” according to a new study. Causes of this are molecular mechanisms that affect gene regulation. These current findings from studies in mice provide clues as to why an active, varied life can help preserve mental fitness in old age. The study appears in the journal Nature Communications.

Human DNA—and this also applies to mice—contains thousands of genes. However, it is not only the genetic blueprint that is decisive for the function of a cell and whether it is healthy or not, but above all those which are called “soft genes.” These are the ones that can be switched on or off according to an individual’s context, experience and environment.

Aging, living conditions and behavior are known to influence this ability to activate genes. The phenomenon, referred to as “epigenetics,” was the focus of the current study.

For this, researchers examined mice that had grown up in different environments: One group of animals experienced, from a young age, an “enriched” environment with toys and tunnel tubes. The rodents of a second group did not have such occupational opportunities. Like socially deprived kids.

When the scientists examined the genome, they found that in those mice that grew up in the stimulating environment, there was, with age, only a relatively small change in certain chemical tags of the DNA. In mice from the low-stimulus environment, the changes between the hippocampi of young and old animals were much more pronounced.

“We registered so-called methyl groups, which stick to the DNA,” explains the research group leader. “These chemical attachments do not alter the genetic information per se. Rather, they influence whether individual genes can be activated or not.”

Such “epigenetic markings” tend to diminish with age, but in the animals with stimulating living conditions, the decrease in methyl groups was comparatively small. Thus, in old mice raised in a varied environment, gene activity had, in a sense, remained young. This affected a series of genes relevant to growing new neurons and cellular connections in the hippocampus. “Epigenetically, these animals retained a younger hippocampus,” the researchers noted. Therefore, the brains of these mice were more malleable—experts speak of greater “neuroplasticity”—than in others of the same age that had grown up in a low-stimulus environment.

The lead author pointed out that many other studies have shown that mice raised in high-stimulus settings perform better on memory tests than those from low-stimulus environments. “It is fair to assume that this mental fitness is due to the stabilization of methylation patterns that we observed,” she said. “Of course, the question is to what extent our findings also apply to humans. However, we have good reasons to believe that the basic epigenetic principles are the same in humans as in mice.”

So, what? I have been bleating on for a long time that the so-called “diseases of old age,” including cognitive decline are not the products of aging per se, but rather of lifestyle and living and working conditions over time. Working in a boring job, having less opportunity to socialize, being economically deprived, staying in one place all your life, are all contrary to what I call our human “design specs.”

Some great recent research has shown that, as far as our DNA is concerned, work is essentially there for two reasons: for socializing and for having fun. The best jobs are, essentially, games people play together. The most productive workplaces are ones which provide variety of work, opportunities to socialize and fun. Not surprising since there are “young” people working there no matter how old they are.

Read more on our design specs and work and health.