The brain has a huge component of cholesterol. It is important enough that the brain makes its own cholesterol. Some of the cholesterol lowering drugs (not all) are able to cross the blood brain barrier and reduce cholesterol in the brain.

Who thought this was a good idea???? (hint: maybe the ones that make lots of money selling drugs???)

Once a person understands the difference between relative risks (what the drug companies use to advertise statins) and absolute risk (tiny) that the studies show benefit (questionable) it raises a red flag. Then considering the "run in" period before the studies they eliminate people that do not "tolerate" the drug, the side effects shown in the studies are a tiny percentage because everyone who was having trouble was eliminated from the trial before it started.

And the drug companies don't even publish the studies that did not work out. Only the successful ones and then not all the data. Supposedly because of "trade secrets". The doctors mostly listen to the drug reps selling the drugs. Few actually read and study the research. I listen to the doctors on line that actually do read the research and report on it.