What Causes Someone Brain To Degrade And Eyesight To Decrease

I'll make this short and simple.

Symptons.
Brain gets fogged, happening more and more overtime.
~ Forgetting the name of objects, replacing with wrong word or made up word, usually multiple per sentence, speaking sentence partly gibberish and last a couple hours straight.
        ~ Like calling a chimney a tee-pee or calling a floor tile a motor mouth. (just to name a few examples).
~ What trying to ask questions, questions come out completely wring and/or unrelated, such as seeing someone with a funny facial expression and asking why they have two heads.
~ Unable to understand what is being said or what you are reading, even basic things.
~ Mind often goes blank, can't even speak, if try to.
      ~ Unable to think, speak, or turn your head; dead to the world.
~ Short term memory loss (often).
      ~ Getting a cartoon from the first to put out temporally to get another one, and forget about it seconds after you taken it out.

Eyesight started to decrease slowly, around the same time. Could have something to do with the brain, or something elsewhere to cause to brain to malfunction.