Caloric Restriction Increases Lifespan But Affects Brain Integrity

Scientific evidence continues to mount in support of the hypothesis that reducing overall calorie intake, while still maintaining a balanced diet, leads to a significant increase in lifespan. Previous research – for macaques, in particular (which have an average lifespan of forty years) – had already demonstrated the beneficial effect on the incidence of age-related pathologies. However, the positive effect on the lifespan of primates has remained controversial. Now, a new study from The French National Center for Scientific Research (CNRS) shows that caloric restriction in lemurs extended lifespan up to 50%. Findings from the new study were released today in Nature through an article entitled “Caloric restriction increases lifespan but affects brain integrity in grey mouse lemur primates.”

To study this question, the researchers focused on the grey mouse lemur, a small primate whose lifespan (around twelve years) makes it a very good model for the study of aging. Moreover, this small lemurid has many physiological similarities with humans.

In the current study, the researchers exposed a group of mouse lemurs to moderate chronic caloric restriction (30% fewer calories than their peers consuming a normal diet) from the outset of early adulthood. Subsequently, the investigators observed their survival data as well as possible age-related alterations. The first result, after the experiment had been running for ten years, was that in comparison to the animals in the control group, the lifespan of those subject to caloric restriction increased by almost 50%.

“We report the most advanced survival data and the associated follow-up to our knowledge of age-related alterations in a cohort of grey mouse lemurs (Microcebus murinus, lemurid primate) exposed to a chronic moderate (30%) caloric restriction,” the authors wrote. “Compared to control animals, caloric restriction extended lifespan by 50% (from 6.4 to 9.6 years, median survival), reduced aging-associated diseases and preserved loss of brain white matter in several brain regions.”

For the first time among primates, the scientists observed that the maximum lifespan had increased. Almost a third of the calorie-restricted animals were still alive when the last animal in the control group died at the aged of 11.3 years. The beneficial effect of calorie restriction was accompanied by the preservation of motor capacities, without any alteration to cognitive performance, and a reduction in the incidence of pathologies usually associated with aging, such as cancer or diabetes.

Interestingly, while the calorie-restricted mouse lemurs presented the morphological characteristics of a younger animal, brain imaging data for these very elderly animals showed a slight loss of grey matter (neuronal cell bodies). “Caloric restriction accelerated the loss of grey matter throughout much of the cerebrum. However, cognitive and behavioral performances were not modulated by caloric restriction,” the authors noted.

The results indicate that chronic caloric restriction is currently the most effective way to extend maximum lifespan and delay the aging process in a non-human primate. The next step for the scientists is to associate chronic caloric restriction with another study parameter, such as physical exercise, in an attempt to further extend the upper limits of lifespan.