When you were born, almost all of the one trillion neurons, or nerve cells, in your brain had already formed. But those neurons still had a lot of growing to do.
As kids grow, neurons in the brain branch out and make new connections. You could even say that the life a neuron is all about connections. If neurons don’t form appropriate connections with each other and other structures in the brain, they’ll eventually die.
Luckily, we’re born with far more neurons than we need, and some neuron loss is a normal part of brain development.
Around age 20, we begin to lose neurons to the process of aging. By 75, nearly one-tenth of the neurons you were born with have died. That may sound frightening, but it doesn’t mean you lose ten percent of your intelligence. Here’s why.
Most neurons can’t divide to form new cells, so there’s no way to replace them if they die. But living neurons continue to grow all of our lives, forming new branches and connections with other neurons. That makes up for much of what we’ve lost. And there’s another type of brain cell, called a glial cell, that can divide to form new cells. Glial cells help neurons do their job better and provide a framework to support them.
But brain power isn’t just about numbers of cells. Eating a well-balanced diet and experiencing and learning new things all influence the way neurons branch and connect. In other words, the more you use your brain, the better it works.