ad·dle 
/ˈædl̟/ verb
ad·dles; ad·dled; ad·dling /ˈædl̟/ verb [+ obj] : to make (someone's mind or brain) unable to think clearly
▪ It's a dangerous poison that's strong enough to addle the brain. ▪ Their brains were addled with/by fear/drugs.
▪ It's a dangerous poison that's strong enough to addle the brain. ▪ Their brains were addled with/by fear/drugs.
— addled adjective
▪ I needed a moment to clear my addled [=confused] brain/mind. ▪ an addled old man
▪ I needed a moment to clear my addled [=confused] brain/mind. ▪ an addled old man
