Whilst the heavy football was a greater risk for eventual brain injury the present ball is not free from causing the same problems.
The brain is like a bag of jelly inside the skull and when the head comes into contact with a football, it causes the brain to vibrate within the skull. For those who play football regularly, it is the succession of contacts that builds up the condition. No one is immune but as all brains are different it is not safe to assume any one individual will be safe if they are heading footballs regularly over years.