At a certain age, your brain stops growing. You stay alive, but some of your brain cells die, and are not replaced. In fact, after the age of 18, a person may lose more than a thousand brain cells each day!
But there’s no danger of your brain ever “burning out,” for the number of nerve cells in your brain is over 100 billion. At the rate of a thousand brain cells lost per day, it would take almost 300,000 years before your brain ran out of cells!
The average human brain weighs only about three pounds!