From comments int the video —
“Around 34:00 in Neil reveals a possible cause for his brain cancer — 28,000 miles ridden in a year…28k miles wearing that motorcycle helmet with integrated bluetooth microwave head cooker. TOXI COM lists tens of thousands of military studies confirming microwaves cause biological harm, including cancer. Think about it.” https://toxi.com
https://www.youtube.com/watch?v=3oob2Py923Q
Peart rode his motorcycle from performance location to location. Many miles. Bluetooth microwaves blasting into his brain all that time. Just a possibility, rarely considered.