Process of age-related cognitive decline unravelled

The process that allows our brains to learn and generate new memories also leads to degeneration as we age, say researchers, including one of Indian-origin from the Massachusetts Institute of Technology (MIT).

The findings by lead study author Ram Madabhushi and colleagues could ultimately help researchers develop new approaches to preventing cognitive decline in disorders such as Alzheimer's disease.

Each time we learn something new, our brain cells break their DNA, creating damage that the neurons must immediately repair, according to Li-Huei Tsai, professor at MIT.

This process is essential to learning and memory.

"Cells physiologically break their DNA to allow certain important genes to be expressed," Tsai said.

However, as we age, our cells' ability to repair this DNA damage weakens, leading to degeneration, Tsai added.

"When we are young, our brains create DNA breaks as we learn new things, but our cells are absolutely on top of this and can quickly repair the damage to maintain the functionality of the system," Tsai said.

"But during ageing, and particularly with some genetic conditions, the efficiency of the DNA repair system is compromised, leading to the accumulation of damage, and in our view this could be very detrimental."

In further studies, the researchers were able to confirm that an enzyme known as topoisomerase III is responsible for the DNA breaks in response to stimulation in the laboratory.

"When we knocked down this enzyme, we found that both double strand break formation and the expression of early response genes was reduced," Madabhushi said.

The researchers said they plan to investigate whether certain chemicals could enhance this DNA repair capacity as we age.

The finding were reported in the journal Cell.