Sex addiction is first and foremost a disease of the brain. Even though it is not injected like a chemical it still dramatically affects brain chemistry creating a dependency on sexual arousal. Sexual arousal provides a hit of the neurotransmitter, dopamine to the reward center of the brain, the nucleus accumbens, a cluster of nerve cells lying underneath the cerebral cortex. Dopamine interacts with other neurotransmitters to take over the brain’s reward related learning. Repeated exposure to addictive sexual images, or behaviors cause nerve cells in the nucleus accumbens and prefrontal cortex to communicate in ways that link liking with wanting and motivates action to seek out the source of pleasure.
In nature, rewards come with time and effort. Addictive behaviors provide a dependable short cut to reward, flooding the brain with dopamine and other neurotransmitters. Viewing porn can release 20 times the amount of dopamine as watching a great movie or having sex within a committed relationship. In the hijacked/addicted brain the pleasure receptors become over whelmed. The brain responds by producing less dopamine or eliminating receptors. It’s like turning the volume down on a speaker when the music gets too loud. As a result the dopamine has less impact on the brain’s reward centers and tolerance develops and behaviors must be escalated. At this point compulsion and craving take over