Most scientists who are not experts in their field don't read the literature for a field directly. Instead, they synthesize their opinions about the field by consulting experts, and weighing various sorts of evidence. In my case, I work in an adjacent field and see presentations from scientists, have casual conversations with them, and read the news articles in major journals.

The raw literature for alzheimer's, as well as biomed in general, is not really easily interpretable. It's rife with errors, misleading statements, and intentional obfuscation.