If you are one who is unconvinced with the reality that the Internet is causing people to have shorter memories, then I'd like to explain why our high-tech world is in fact causing human brains to function differently. First of all, I'd like to state a fact, which I think we all know intuitively, even if there are no major research papers on the topic. And that is; "the brain works much like a muscle, and if you don't use it, you lose it." Now then, I can say we all believe that, and understand that principle.
Now, let's talk about your cell phone and how it stores all the phone numbers that you used to have to remember. And let's talk about the reason that it's no longer important to remember dates, events, or famous people - after all, you can look it up on the Internet anytime you want it's always there 24-7-365. Even kids wonder how come they have to do reports on various topics in school, as all the information is already there on Wikipedia, why should they have to redo it? Worse, they wonder why they can't just copy it, are you beginning to see the problem.
And, I think most of us realize that rote memorization doesn't work, or at least it doesn't work that well, and it's probably a lousy way to teach young humans in school. Nevertheless, we still do that, and you and I, and all of our friends have had a lot of training and memorization, but these days we don't use our memory very much, and therefore, often we feel it is lacking.
No, it's probably not onset Alzheimer's, but rather the fact that our brain just doesn't work that way anymore. We've not been reinforcing the memorization of information as we used too.
Still, I wouldn't say that the high-tech world and information age will totally destroy human memory, because Alas, you still have to know what to search, so you do have to remember the concept, even if you can never how to spell the names, or remember the dates behind that subject. Please consider all this.