Drug and alcohol use spikes wildly during the 30-day run-up to New Year’s Eve. But which drugs are actually most addictive? The answer may surprise you.
Many factors determine whether you’ll become addicted to a drug: your genetic makeup, social history, the drugs your friends take, how much money you make. But the chemical makeup of drugs guarantee that certain drugs are more addictive than others. The hardest ones to kick—heroin, for instance—actually train your brain to crave them. A team of researchers led by professor David Nutt of London’s Imperial College recently set out to determine which drugs were most harmful based on their addictive properties (the resulting article suggested that alcohol and tobacco are more harmful than cannabis and ecstasy, and led to Nutt getting sacked as the UK’s top drug adviser). Dutch scientists replicated the London study and devised a “dependency rating” that measured addictive potency of the biggest drugs out there on a precisely calibrated scale of 0-to-3.
Dependence Rating: 2.89
No surprise here: heroin’s addictiveness is the stuff of legend. As an opiate, it affects opioid receptors throughout the body and mimics endorphins, reducing pain and causing pleasure. Areas of the brain involved in reward processing and learning are stocked with tons of these opioid receptors, so when you inject heroin, you are basically training your brain to make you crave it. Pair that with nasty withdrawal symptoms and high fat solubility (which allows it to get into your brain quickly), and you have the most addictive drug in the world.
An estimated 281,000 people received treatment for heroin addiction in the U.S. in 2003, according to the National Institute on Drug Addiction. And with the alarming rise of young people making the switch from opioid prescription drugs like Oxycontin to heroin, we’ve got a major problem on our hands.
2. Crack Cocaine
Dependence Rating: 2.82
Crack cocaine is the crystal form of cocaine, which normally comes in a powder form. It comes in solid blocks or crystals varying in color from yellow to pale rose or white. Crack is heated and smoked. It is so named because it makes a cracking or popping sound when heated. Crack, the most potent form in which cocaine appears, is also the riskiest. It is between 75% and 100% pure, far stronger and more potent than regular cocaine.
Although crack cocaine and powder cocaine have similar chemical compositions and effects, smoking processed crack causes a faster, higher rush that lasts for less time (about 10 minutes, versus 15-30 for powder cocaine). The intensity of the high combined with the efficient method of ingestion—smoking—are the big reasons why addiction rates are dramatically higher for crack than they are for snorted powder. In 2010, there were an estimated 500,000 active crack cocaine addicts in the United States.
Dependence Rating: 2.82
It’s well known that nicotine is one of the hardest drugs to quit. It’s not surprising then that the drug has a 2.82 dependence rating. Nicotine is similar to heroin and crack in that it mimics a common neurotransmitter, though nicotine doesn’t cause the rush of heroin or crack, it’s biologically similar in a crucial way: it mimics a common neurotransmitter—so well that scientists named one of the acetyl-choline receptors after it. Smoking regularly reduces the number and sensitivity of these “nicotinic” receptors, and requires that the user keep ingesting nicotine just to maintain normal brain function.
Nicotine doesn’t sound so innocent when you consider that one in every five deaths are smoking related and there are a whopping 50 million users in the U.S.
In a clinical setting, tolerance to this drug is actually considered a good thing when treating a heroin addiction. A junky getting treated with methadone will quickly become resistant to its euphoric effects and use it to keep heroin withdrawal symptoms at bay. The problem is this: tolerance to methadone is a sign of an addiction to methadone.
5. Crystal Meth
Dependence Rating: 2.24
Directly mimicking a natural neurotransmitter “teaches” your brain to want a drug—that’s how nicotine and heroin work. Crystal methamphetamine takes it to the next level: it imitates the reward chemical dopamine and the alertness chemical norepinephrine, causing your neurons to release more of both—all the while training your brain to want them more. What’s worse, the drug can damage dopamine- and norepinephrine-releasing neurons, which leads to a drastic decrease in their production, thereby making you crave more meth. It’s an addict’s nightmare and a marketer’s dream.