Dr. Fatta Nahab, a neurologist who directs the Functional Imaging of Neurodegenerative Disorders Lab at the University of California San Diego Health's Movement Disorder Center, sits at his desk Monday, Sept 17, 2018, in San Diego. Nahab spent years going through regulatory hoops to get approval to import marijuana from Canada, to study whether cannabis can help treat essential tremor, a shaking condition affecting millions of people. (AP Photo/Julie Watson)
