| This is a question that people often ask but is actually | | | | disagree with Henningfield rating heroin first and |
| a very difficult one to answer. Addiction is not just one | | | | Benowitz rating cocaine. |
| single and simple process, it is a complex process that | | | | The fourth criterion is dependence. This is defined as |
| has both physical and psychological aspects. | | | | the difficulty in quitting, or staying off the drug, usually |
| Nevertheless despite this complexity two attempts | | | | measured by the number of users who eventually |
| have been made to determine the most addictive drug. | | | | become dependent. For many dependence is viewed |
| Independently Dr. Jack E. Henningfield of the National | | | | as the hallmark of addiction and how 'addiction' is |
| Institute on Drug Abuse and Dr. Neal L. Benowitz of | | | | usually measured by the medical profession. For this |
| the University of California at San Francisco, ranked | | | | criterion both researchers are again in agreement as |
| six psychoactive substances, nicotine, heroin, cocaine, | | | | they rate nicotine highest for dependence. For the |
| alcohol, caffeine and marijuana, on the five criteria they | | | | other drugs they both rated them in the same order |
| felt were most important in addiction. | | | | that is highest for dependence, nicotine, then heroin, |
| The first of these criteria was withdrawal. This is | | | | cocaine, alcohol, caffeine and last marijuana. |
| defined as the severity of withdrawal symptoms | | | | The final criterion is intoxication. This is the degree of |
| produced by stopping the use of the drug. Both | | | | intoxication produced by the drug in typical use. Again |
| researchers rated alcohol as having the most severe | | | | the researchers are in agreement and rate alcohol as |
| withdrawal symptoms, for example hallucinations and | | | | the most intoxicating of the drugs. |
| convulsions, and the fact that withdrawal from alcohol | | | | Given the complexity of the addictive process it is not |
| is the only one of the included drugs that is potentially | | | | surprising that there is not a clear 'winner' in all criteria. |
| fatal. | | | | What some may find surprising is that for both |
| The second criterion is reinforcement, that is the drug's | | | | researchers caffeine ranked higher than marijuana on |
| tendency to induce users to take it again and again. | | | | a number of the criteria and indeed Berowitz rates |
| This is influenced by the feelings that taking the drug | | | | caffeine higher than marijuana for dependence. |
| brings, that is whether it is a pleasurable high or not, | | | | These results have been quoted many times by many |
| obviously if the feelings are negative there will be little | | | | researchers, commentators and reporters. They are |
| incentive to repeat the experience. Again both | | | | usually interpreted as nicotine, or tobacco smoking, |
| researchers were in agreement and rated cocaine as | | | | being named the most addictive substance purely on |
| the most reinforcing. | | | | the definition of the difficulty in refraining. What the |
| The third criterion was tolerance, this is defined as the | | | | results do show is that addiction is a complex and |
| user's need to have ever-increasing doses to get the | | | | multi-facetted activity and that it is impossible to reduce |
| same effect. For the first time the researchers | | | | it to a simple metric. |