[dreamcompiler]

It's a vasodilator, which is means it also reduces blood pressure (that was the drug's original purpose).

So it's conceivable that it could clear a wider exit pathway for amyloid plaques and other garbage that accumulates in the brain.

It's also why a significant fraction of men who take it develop headaches so painful that sex is the last thing on their mind. Welcome to vasodilators.

Oh and if you already take nitroglycerin for cardiac angina, you can't take viagra because you get twice the headache -- right before you pass out because your blood pressure crashed.