Science lists the five most addictive drugs https://t.co/oQZPf3Ct8t pic.twitter.com/QHW12VCODa

— The Conversation (@ConversationUK) March 3, 2016

1. Heroin

Nutt et al.’s experts ranked heroin as the most addictive drug, giving it a score of 2.5 out of a maximum score of 3

2. Alcohol

Although legal in the US and UK, alcohol was rated as the second most addictive substance by Nutt et al.’s experts (scoring 2.2 out of a maximum of 3).

3. Cocaine

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.

4. 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.

5. Nicotine

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.