Why Does Our Brain Function Slow Down As We Get Older?

Scientists have discovered a possible explanation for why our brains often become more reluctant to function as we age.

The research, led by Professor Andy Randall and Dr. Jon Brown from the University of Bristol’s School of Physiology and Pharmacology and published this week in Neurobiology of Aging, identified a novel cellular mechanism responsible for changes in neuron activity. And since our brains typically use electrical signals to encode and convey information, any alterations to this activity could be the basis of cognitive decline during normal healthy aging.

During their work, the research team examined the brain’s electrical activity by making recordings of electrical signals in single cells of the hippocampus, a structure with a crucial role in cognitive function, to characterize “neuronal excitability” — or how easy it is to produce brief but very large electrical signals called action potentials, which occur in practically all nerve cells and are absolutely essential for communication within our nervous system circuits.

Scientists found that older brains have more difficulty making hippocampal neurons generate those action potentials, and they demonstrated this arises from changes to the activation properties of membrane proteins called sodium channels, which mediate the rapid upstroke of the action potential by allowing a flow of sodium ions into neurons.

“Much of our work is about understanding dysfunctional electrical signalling in the diseased brain, in particular Alzheimer’s disease,” Dr. Randall said in a press release. “We began to question, however, why even the healthy brain can slow down once you reach my age.”

“Previous investigations elsewhere have described age-related changes in processes that are triggered by action potentials,” he added, “but our findings are significant because they show that generating the action potential in the first place is harder work in aged brain cells.”