The Science of Addiction

Dopamine is often considered the 'happy' hormone or neurotransmitter. Despite it's many other functions, dopamine is well known for feelings of pleasure, contentment, and alertness. Dopamine has been implicated in the body's changes of mood, heart rate, and even in the ability to learn.

When functioning as a neurotransmitter, dopamine is produced in the brain, in a special area called the substantia nigra. This term, "black cells," refers to the fact that the cells have melanin pigment. The dark color is a result of the end reactions of forming dopamine. In some diseases, a change in the substantia nigra can be an indicator. With Parkinson's disease, the dopamine neurons in the substantia nigra begin to change color, indicating a lack of dopamine synthesis. In what is considered the opposite of Parkinson's disease, Huntington's disease has an overabundance of dopamine present in the brain.

In everyday life, dopamine is slowly released into the synaptic cleft of neurons to maintain mood. But dopamine levels can be stimulated by food, activities, behaviors, drugs, and is essential to the pleasure center of the brain. In addition, dopamine is important in motivation, reward and desire. But how does dopamine effect addictions?

Alcohol
Although the main effects of alcohol can be felt through a different pathway, dopamiine does play a significant role in initial use of alcohol. Initial use of alcohol triggers an increase of dopamine. Alcohol not only causes an Increase in dopamine levels which affects the pleasure center(nucleus accumbens) of the brain, but alcohol may also affect monoamine oxidase, an enzyme which breaks down dopamine. As a result, an overabundance of dopamine can lead to a happy feeling. Yet, continual triggering of this response(chronic use) can cause an increase in dopamine receptor along neurons. Because your body must then produce more dopamine to satisfy the receptors, addiction and craving for the same sort of response can result.

Weed/Marijuana/Cannabis
Marijuana can indirectly affect dopamine levels. If following a certain pathway(the CB-1 receptor), the active ingredient in marijuana, THC, works by blocking a neurotransmitter called GABA from entering the system. GABA is a molecule which works to inhibit dopamine release, as part of a checks/balances system in the body. With less GABA, more dopamine is released, leading to more receptors present on cells and feelings of addiction.

Aphetamines (Methamphetamine, etc)
Amphetamines actually achieve their goals by mimicking the structure of dopamine. Amphetamines will use the dopamine transport system to store themselves in a cell. Amphetamines will, more or less, kick dopamine out of a cell and into the synapse. The resulting dopamine levels cause feelings of pleasure, and can lead to addiction if more receptors are synsthesized by teh body. In addition, amphetamine can also degrade monoamine oxidase, the enzyme mentioned before that is responsible for breaking down dopamine.

Cocaine
Cocaine is similar to the amphetamines, but much more intense. Not only does it block reuptake and storage of dopamine, but it also affects reuptake of norepinephrine and serotonin, both major neurotransmitters with roles in perception, fight or flight, and other important body functions. Cocaine is difficult for the body to break down, and the overabundance of dopamine will lead to addiction easily.

Knowing a little about how the body - not the mind - becomes addicted can perhaps aid us in dealing with close personal friends or family members undergoing addiction of any sort. The dopamine pathway does not have to be affected by drug interactions to cause addiction. Continuous positive response to anything - from cocaine to pornography to popping pimples in the morning - can cause an increase in dopamine receptors and lead to addiction.