Experts ranked heroin as the most addictive drug, giving it a score of 3 out of a maximum score of 3. Heroin is an opiate that causes the level of dopamine in the brain’s reward system to increase by up to 200% in experimental animals. In addition to being arguably the most addictive drug, heroin is dangerous, too, because the dose that can cause death is only five times greater than the dose required for a high.
Heroin also has been rated as the second most harmful drug in terms of damage to both users and to society.
Cocaine directly interferes with the brain’s use of dopamine to convey messages from one neuron to another. In essence, cocaine prevents neurons from turning the dopamine signal off, resulting in an abnormal activation of the brain’s reward pathways. It is estimated that between 14 million and 20m people worldwide use cocaine.
Crack cocaine has been ranked by experts as being the third most damaging drug and powdered cocaine, which causes a milder high, as the fifth most damaging. About 21% of people who try cocaine will become dependent on it at sometime in their life.
Nicotine in e-cigs, tobacco linked to heart disease
Nicotine is the main addictive ingredient of tobacco. When somebody smokes a cigarette, nicotine is rapidly absorbed by the lungs and delivered to the brain.
More than two-thirds of Americans who tried smoking reported becoming dependent during their life. In 2002 the WHO estimated there were more than 1bn smokers and it has been estimated that tobacco will kill more than 8m people annually by 2030.
- Barbiturates (“downers”)
Barbiturates — also known as blue bullets, gorillas, nembies, barbs and pink ladies — are a class of drugs that were initially used to treat anxiety and to induce sleep. They interfere with chemical signaling in the brain, the effect of which is to shut down various brain regions. Barbiturate dependence was common when the drugs were easily available by prescription, but this has declined dramatically as other drugs have replaced them.
Alcohol has many effects on the brain, but in laboratory experiments on animals it increased dopamine levels in the brain’s reward system by 40% to 360% — and the more the animals drank the more dopamine levels increased.
No amount of alcohol is good for your overall health, global study says
Some 22% of people who have taken a drink will develop dependence on alcohol at some point during their life.
Initially reported by CNN.com. Written by: Eric Bowman a lecturer in psychology and neuroscience at the University of St. Andrews. For the full article go to www.theconversation.com.