Cannabis/marijuana can possibly provide benefits to many brain disease. THC is psychoactive but other compounds are not and may also be efficacious for brain diseases including Azheimers.
Patent ranted to US Gov 2003  Business category in Denver Post 2016 article:
Patent No. 6,630,507: _Why the U.S. government holds a patent on cannabis plant compounds
It’s about technology transfer, not legalization_ by	 Alicia Wallace The Denver Post  8.28.16 UPDATED 10.2.16

_In the case of No. 6,630,507, the researchers discovered that non-psychoactive compounds in cannabis may have antioxidant properties that could be beneficial in the treatment of certain neurological diseases....

_“This patent describes the therapeutic potential for cannabinoid chemical compounds that are structurally similar to THC, but without its psychoactive properties, thereby treating specific conditions without the adverse side effects associated with smoked marijuana,”_  clip see article URL in a comment to follow.