There are other factors aside from genetics and environment that can increase potential for addiction. Research has shown that the faster a drug can reach the brain, the more likely it is to be addicting. Different methods of delivery-smoking, injecting, or snorting- largely influence how quickly a drug finds the brain. Delivery methods become an important factor when ranking the addiction potential of a drug.
The fastest way to get a drug to the brain is by smoking it. When a drug like tobacco smoke is taken
into the lungs, nicotine (the addictive chemical in tobacco) seeps into lung blood where it can quickly
travel to the brain. This fast delivery is one reason smoking cigarettes is so addicting.
Injecting a drug directly into a blood vessel is the second fastest way to get a drug to the brain, followed by snorting or sniffing it through the nose. The slowest mode of delivery is by ingestion, such as drinking alcohol. The effects of alcohol take many minutes rather than a few seconds to cause behavioral and biological changes in the brain.
Crack cocaine (which is smoked) is much more addicting than powdered cocaine (which is snorted).
This brain region is affected during both the smoking and snorting of a drug.
Rapid drug delivery changes these brain regions, altering gene expression and neural circuitry in a way that could accelerate the transition to addiction.
These three brain regions are less affected during the snorting of a drug.
frontal lobe of the brain
Animal studies indicate that, when a drug is smoked, the brain regions affected most are those that control motivation, decision-making, and behavior in the frontal lobe. The human brain is shown here. These studies were actually done in rats and have not yet been replicated in the human brain.
Nobody likes to wait, so users often choose a delivery method that gets them higher, faster. As addiction progresses, users often seek out the more immediate and more intense high. But this doesn’t seem to be the only reason that rapid delivery is an important factor in addiction. Recent evidence suggests that the mode of delivery can actually influence which part of the brain is most affected by a drug. Rapid delivery, such as smoking, affects brain regions that facilitate addiction.
A patch placed on the skin is used to slowly deliver nicotine to a smoker trying to quit.
Increased knowledge about drug delivery methods is leading to new addiction therapies. It turns out that delivering a drug slowly, by ingestion or through the skin, produces a weaker, longer-lasting effect. Slow delivery allows the drug to temporariliy stabilize the brain and help reduce withdrawal symptoms over a longer period of time. And slow delivery is less addicting! So it's becoming an increasingly popular treatment option.