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.