Eating, Aging, and the Brain

Two recent studies shed new light on the relationship between food and the brain.

The first study involves mice on a calorie-restricted diet. Restricting calories to about 70% of normal intake kept the mice—and their rodent brains—young when compared to control mice who could eat whenever they wanted. And while there’s no proof yet that this works with human beings, there is a lot of interest by researchers in finding out what is going on in the relationship between aging and eating.

The latest research is reported in the December 19 of PNAS. Researchers at the Catholic University of Sacred Heart in Rome report their finding that a naturally-occurring protein, CREB1, plays a key role in mediating between caloric restriction and the delay of aging. Caloric restriction seems to trigger CREB1, which in turn activates many other genes involved in longevity and brain function.

What is new in this research is the relationship between caloric restriction and CREB1 activity. Discovering how these molecules interact opens the possibility that the activity of CREB1 can be increased without having to keep to a fairly austere diet.

According to Giovambattista Pani, one of the lead researchers, “Our hope is to find a way to activate CREB1, for example through new drugs, so to keep the brain young without the need of a strict diet.”

“This discovery has important implications to develop future therapies to keep our brain young and prevent brain degeneration and the aging process. In addition, our study shed light on the correlation among metabolic diseases as diabetes and obesity and the decline in cognitive activities,” according to Dr. Pani.

The second study is published in the December 28 issue of Neurology and does involve human beings. Just in time for New Year’s resolutions, researchers at Oregon State University report on the brains and the diets of 104 seniors with an average age of 87. The result is pretty sobering. Those who ate fast foods and snack loaded with trans-fats scored much worse on cognitive tests than those who ate diets rich in the healthy oils commonly found in fish or consumed high levels of vitamins B, C, D, and E.

How much worse? The fast-food seniors scored 17% lower on thinking and memory tests and had a shocking 37% lower active brain size based on an MRI. And that’s after other factors such as age or education level are removed. Diet alone, it appears, makes a significant difference. Eating the right food seems to help slow down the age-related shrinkage of the brain.

Someday there might be a pill that makes us and our brains resist aging. For now, it’s what we eat that counts. These results need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet," according to Gene Bowman of the Oregon Health & Science University in Portland and author of the study.

This would not have surprised Saint Athanasius, bishop of Alexandria in the mid-4th century. Like many of his age, Athanasius was fascinated by the story of Saint Anthony of Egypt, one of the earliest Christian ascetics. Athanasius wrote a spiritual biography of Anthony, interpreting his life and turning him into the prototype of Christian monks.

Anthony gave away the family fortune and lived in isolation in the Egyptian desert, eating almost nothing. The result? He lived to 105 and was known for his wisdom to the very end.

Todd Daly has written about Athanasius and Anthony, including an essay in my recent book, Transhumanism and Transcendence. Daly makes it clear that Anthony’s purpose was not longevity or a youthful brain. This is no science experiment, and if Anthony is the first monk, he’s not the first transhumanist. But according to Athanasius (and to Daly), Anthony is conducting a spiritual experiment. His question is whether it is possible to regain some small portion of the original human condition…humanity as God intended, in other words, rather than the fallen humanity we experience. By denying his body, he sought to expand his soul. Without realizing it, he kept his brain from shrinking.

The amazing thing is that by asking a seemingly arcane theological question—and by sticking with it for decades—Anthony anticipates today’s research.

The PNAS article was published on December 19. The Oregon study was published online on December 28 by the journal Neurology.

Are You as Empathetic as a Rat?

Empathy is the capacity to share the emotional state of another. Politicians claim to have it when they say “I feel your pain.”

Even if they do not always show it, human beings are clearly capable of empathy. Other primates such as chimps have been observed acting in a way that is best explained by empathy. Rather than acting for their own benefit, they sometimes act because they share the feeling or distress of another chimp. Such behavior is said to be “empathy-driven.”

Once it was thought that only human beings could feel empathy. Now researchers are finding that empathy-driven behavior is more widespread than previously imagined. Not just other primates but even rodents, it seems, are biologically capable of empathy. For all the differences between the human and the rat brain, we share fundamental circuits that make it possible to feel the emotions of another, particularly when the other is in pain or distress.

In a simple experiment reported in the December 9 issue of the journal Science, researchers provide solid evidence that the much-maligned rat is capable of acting in a way that is most easily explained by empathy.

"This is the first evidence of helping behavior triggered by empathy in rats," said Jean Decety, a member of the research team at the University of Chicago. "There are a lot of ideas in the literature showing that empathy is not unique to humans, and it has been well demonstrated in apes, but in rodents it was not very clear. We put together in one series of experiments evidence of helping behavior based on empathy in rodents, and that's really the first time it's been seen," Decety said in a release issued by the University.

In order to act in a way that is empathy-driven, an animal must be capable of “emotional contagion.” To test whether rats have this capacity, an experiment was designed Chicago psychology graduate student Inbal Ben-Ami Bartal. Two rats were placed in an enclosure, one of them roaming freely while the other was locked inside a tube. The free rat, in time, could discover how to open the lock, but there was no reward for doing so.

The experiment was designed observe whether rats show they are capable of emotional contagion. Was the free rat biologically capable of emotional concern or what the paper defines as “an other-oriented emotional response elicited by and congruent with the perceived welfare of an individual in distress”?

PHOTO: ©Science/AAAS.

The free rats not only learned to open the container but did so repeatedly when it held another rat, something they did not do if it was empty or if it contained a stuffed animal.

Even more striking was their behavior when chocolate chips were involved. In one variation on the experiment, two enclosures were used, one with an enclosed rat and the other with five pieces of chocolate. The free rat has a choice: free the cagemate or eat the chocolate first. In the absence of empathy, the free rat will make the selfish choice. But at least half the time, the rat freed its cagemate first. According to the report, “these results show that the value of freeing a trapped cagemate is on par with that of accessing chocolate chips.”

"On its face, this is more than empathy, this is pro-social behavior," said Jeffrey Mogil of McGill University, who was not involved in the study. "It's more than has been shown before by a long shot.”

Without claiming to know what rats think, the authors conclude their report with their opinion that “the free rat was not simply empathetically sensitive to another rat’s distress but acted intentionally to liberate a trapped” member of their own species.

If rats are indeed capable of empathetic feelings, then it becomes clear that the biological substrate for shared emotion is deep in our evolutionary past and deep in the earlier parts of our brains. Far from being uniquely human, empathy seems to be widely shared. What is uniquely human, perhaps, is the way we override it with self-interest.

As I prepared this post, I was interrupted several times by others who were speaking of the history of racism in America and particularly the history of slavery. When I saw the pictures of rats in their enclosure, my mind went to chains and slave ships. If empathy is so deep in our mammalian evolution, so deeply rooted in our brains, what extraordinary rationalizations do we conjure up to negate it?

The paper, "Empathy and Pro-Social Behavior in Rats," is published Dec. 9 by the journal Science. http://www.sciencemag.org/content/334/6061/1427.abstract

Violence and Children's Brains

When children are exposed to violence in the family, their brains are visibly changed. That’s the disturbing message of new research published in tomorrow’s issue of Current Biology.

According to the research article, exposure to violence at home can “represent a form of environmental stress that significantly increases [the] risk of later psychopathology, including anxiety.” It’s as if violence tunes the child’s brain to expect more violence.

Earlier studies have shown that physically abused children show “selective hypervigilance to angry cues,” such as pictures of angry faces. Another earlier study used functional magnetic resonance imaging (fMRI) to show increased brain reactivity. When individuals with anxiety disorder where shown angry faces, two brain regions were overly reactive: the anterior insula (AI) and the amygdala. The same response was found in soldiers exposed to combat.

The new research takes this a step further. Children exposed to family violence, including violence between parents, also showed the same increased brain reactivity. The reaction was quite specific in that they responded to pictures of angry faces, not sad faces.

Most important, perhaps, is that this study looked at brain function rather than symptoms of anxiety or depression. In terms of behavior, the children seemed quite normal. Their brains, however, tell a different story, one of being tuned to be anxious.

Some might suggest that given all the violence in the world, the reaction is beneficial. Maybe it’s a good thing that some human beings learn to be especially responsive to potential threats.

But as the researchers note, excessive reactivity “may also constitute a latent neurobiological risk factor increasing vulnerability to psychopathology.” The researchers also found that the degree of the brain reactivity depended on the severity of the violence.

The research “underlines the importance of taking seriously the impact for a child of living in a family characterized by violence. Even if such a child is not showing overt signs of anxiety or depression, these experiences still appear to have a measurable effect at the neural level,” said Eamon McCrory of University College London, lead author, in a press release from the journal.

More than that, this research shows how violence and trauma affect human beings in ways that permanently alter the brain.

The article, “Heightened Neural Reactivity to Threat in Child Victims of Family Violence,” appears in the December 6 issue of Current Biology.

For previous work by some of these same researchers, see “The Impact of Childhood Maltreatment: A Review of Neurobiological and Genetic Factors,” published in July in Frontiers in Psychiatry.