A new study has found that "runaway" development in the brain is a potentially significant factor in age-related loss of function.
Researchers have now identified a gene regulatory link between changes in the young and aging brain.
The brain undergoes rapid growth and development in the early years of life and then degenerates as we progress into old age, yet little is known about the biological processes that distinguish brain development and aging.
"In development, many genes are turned on and off by regulators, such as transcription factors and microRNAs. The question is, do all of these regulatory processes cease once adulthood is reached, or are they still active in aging?" said Mehmet Somel, postdoctoral researcher at the Shanghai Institutes for Biological Sciences.
The researchers investigated messenger RNA (mRNA), microRNA, and protein expression changes in the prefrontal cortex of humans and rhesus macaque monkeys over the life span of each species.
The group found that distinct patterns of gene regulation in the prefrontal cortex do not stop at maturity, instead persisting into old age, a phenomenon that was observed for many different functional processes.
Previous work has shown that neuronal genes gradually lose activity with age, attributed to an accumulation of damage in neuronal cells over a lifetime.
The researchers showed that this process begins as early as three to four years of age, suggesting that these changes may be normal developmental regulation that continues long into old age.
While this regulation is likely to be beneficial during development, at old age continuation of the gene regulation, or "runaway" development, might be detrimental.
Interestingly, they found the runaway neuronal development to be conserved in macaques, but it occurs an accelerated rate.
Because the regulatory processes progress much faster, the authors suggest that this could be a significant contributor toward limiting the life span of macaques to only about one-third that of humans.