How Science Is Unlocking the Secrets of Addiction
Read the full article at National Geographic.
Patrick Perotti scoffed when his mother told him about a doctor who uses electromagnetic waves to treat drug addiction. “I thought he was a swindler,” Perotti says.
Perotti, who is 38 and lives in Genoa, Italy, began snorting cocaine at 17, a rich kid who loved to party. His indulgence gradually turned into a daily habit and then an all-consuming compulsion. He fell in love, had a son, and opened a restaurant. Under the weight of his addiction, his family and business eventually collapsed.
He did a three-month stint in rehab and relapsed 36 hours after he left. He spent eight months in another program, but the day he returned home, he saw his dealer and got high. “I began to use cocaine with rage,” he says. “I became paranoid, obsessed, crazy. I could not see any way to stop.”
When his mother pressed him to call the doctor, Perotti gave in. He learned he would just have to sit in a chair like a dentist’s and let the doctor, Luigi Gallimberti, hold a device near the left side of his head, on the theory it would suppress his hunger for cocaine. “It was either the cliff or Dr. Gallimberti,” he recalls.
Gallimberti, a gray-haired, bespectacled psychiatrist and toxicologist who has treated addiction for 30 years, runs a clinic in Padua. His decision to try the technique, called transcranial magnetic stimulation (TMS), stemmed from dramatic advances in the science of addiction—and from his frustration with traditional treatments. Medications can help people quit drinking, smoking, or using heroin, but relapse is common, and there’s no effective medical remedy for addiction to stimulants like cocaine. “It’s very, very difficult to treat these patients,” he says.
More than 200,000 people worldwide die every year from drug overdoses and drug-related illnesses, such as HIV, according to the United Nations Office on Drugs and Crime, and far more die from smoking and drinking. More than a billion people smoke, and tobacco is implicated in the top five causes of death: heart disease, stroke, respiratory infections, chronic obstructive pulmonary disease, and lung cancer. Nearly one of every 20 adults worldwide is addicted to alcohol. No one has yet counted people hooked on gambling and other compulsive activities gaining recognition as addictions.
Desire depends on a complex cascade of brain actions, but scientists believe that the trigger for this is likely to be a spike in the neurotransmitter dopamine. A chemical messenger that carries signals across synapses, dopamine plays wide-ranging roles in the brain. Most relevant to addiction, the flow of dopamine heightens what scientists call salience, or the motivational pull of a stimulus—cocaine, for instance, or reminders of it, such as a glimpse of white powder. Each drug that’s abused affects brain chemistry in a distinct way, but they all send dopamine levels soaring far beyond the natural range. Wolfram Schultz, a University of Cambridge neuroscientist, calls the cells that make dopamine “the little devils in our brain,” so powerfully does the chemical drive desire.
How powerfully? Consider the strange side effect of medications that mimic natural dopamine and are used to treat Parkinson’s. The disease destroys dopamine-producing cells, primarily affecting movement. Dopamine-replacement drugs relieve the symptoms, but about 14 percent of Parkinson’s patients who take these medications develop addictions to gambling, shopping, pornography, eating, or the medication itself. A report in the journal Movement Disorders describes three patients who became consumed by “reckless generosity,” hooked on giving cash to strangers and friends they thought needed it.
Through learning, the signals or reminder cues for rewards come to provoke surges of dopamine. That’s why the aroma of snickerdoodles baking in the oven, the ping of a text alert, or chatter spilling out the open door of a bar can yank a person’s attention and trigger craving. Childress has shown that people who are addicted don’t have to consciously register a cue for it to arouse their reward system. In a study published in PLoS One she scanned the brains of 22 recovering cocaine addicts while photos of crack pipes and other drug paraphernalia flashed before their eyes for 33 milliseconds, one-tenth the time it takes to blink. The men didn’t consciously “see” anything, but the images activated the same parts of the reward circuitry that visible drug cues excite.