WHY IT IS DIFFICULT FOR OLDER PEOPLE TO LEARN HOW TO USE COMPUTER？

WHY IT IS DIFFICULT FOR OLDER PEOPLE TO LEARN HOW TO USE COMPUTER？

Nowadays, computer is being a necessary in people's daily life, more and more people want to learn how to use it, it's being broadly used in every field: factories, banks, hospitals, goverments, schools and so on.
While it's not an easy thing for older people to learn how to use computer, why? When people geting older and older, the knowledge they learned is more and more, but the learning speed is becoming slower and slower, if a young boy learned how to use computer in two months, the older people may use half an year, they learn and forget, but for young people, they will remember the skills for more longer times.
Besides memory reason above, the reaction ability between old and young is also quite different, young people move more speedly than olders, old people consider more than young before doing some actions, that's why the speed becomes slower.
Does that means older