Addiction is a physiological condition that is capable of changing the structure of the brain. Whether it is drugs, candy, energy drinks, sex or gambling, the addiction toward these factors is produced from the same brain circuitry known as the limbic system which is responsible for controlling our emotional and behavioral responses to information. There are equal amounts of two types of neurotransmitters present in our brain. The two types are: Excitatory neurotransmitters such as dopamine and endorphin that get their target cells filled up with chemical energy, and inhibitory neurotransmitters such as serotonin which is responsible for keeping target cells calm and mellow. They are present in equal amounts in the brain and excitatory neurotransmitters can be more dangerous than inhibitory neurotransmitters. Endorphin, an excitatory naurotransmitter acts as a painkiller. Dopamine levels rise in response to pleasurable activities and provides the brain with an exciting sensation, making the body believe that it should continue performing the same action in the future. This small concept has a vast influence on how addiction is caused.

The only thing all addictive substances have in common is that they produce a pleasurable amount of dopamine, giving them the ability to hijack our dopamine system. While dopamine has a pleasure component, it is much more significant in creating desire. As substance use increases, the brain circuits adapt and reduce their sensitivity to dopamine by reducing the number of receptors available to try to moderate its effects. This is known as the hypo-functioning reward system which makes artificial and natural pleasures hard to experience since the number of dopamine receptors present are low. This also causes the addict to seek more dopamine to match the level of dopamine released when the addictive substance was consumed one of the first few times and is also the reason why many addictions can continue long after any actual pleasure is gone.

Addictive drugs have the ability to imitate our natural neurotransmitters and artificially change their levels. For example, Heroin, Codine and morphine are extremely addictive because their structure is extremely similar to that of endorphin. They bind to nerve cell receptors made for endorphin in huge numbers which magnifies endorphins pain killing ability, creating a feeling of euphoria. Whereas, Nicotine mimics a neurotransmitter called acetylcholine which triggers the release of large amounts of dopamine.

The amount of dopamine receptors present in the brain can vary from person to person which is why it is easier for some people to be addicted to substances and behaviors more easily. For addictive substances and behaviors, the anticipation is greater than the reward, which is what makes our brains stay addicted to them and want to return to the feeling of its consumption.

The same chemical reactions brought by substance abuse are similar to those brought about by addictive behaviors such as gambling. Not only winning but the near-winning moments and risky moments while gambling also enhances dopamine in the limbic system. Almost winning something, causes your brain to anticipate future rewards as it enjoys predicting patterns, but something like gambling is inherently unpredictable, creating more desire to be able to predict the situation and gamble more which is why it can be extremely addictive.