ave you ever been to Enfield? I had never even heard of it until I was 23 and living in London for graduate school. One afternoon, I received notification that a package whose arrival I had been anticipating for days had been bogged down in customs and was now in a FedEx warehouse in Enfield, an unremarkable London suburb. I was outside my flat within minutes of receiving this news and on the train to Enfield within the hour, staring through the window at the gray sky. The package in question, sent from Los Angeles, contained my monthly supply of Adderall.

Adderall, the brand name for a mixture of amphetamine salts, is more strictly regulated in Britain than in the United States, where, the year before, in 2005, I became one of the millions of Americans to be prescribed a stimulant medication.

The train to Enfield was hardly the greatest extreme to which I would go during the decade I was entangled with Adderall. I would open other people's medicine cabinets, root through trash cans where I had previously disposed of pills, write friends' college essays for barter.