Disease (excluding infectious disease) is often based on genetics, inherited traits passed down from generation to generation through DNA, and addiction is no exception.The disease of alcoholism and addiction is about 60 percent genetic the other 40 percent is environmental.To experience addiction, we must first trigger the expression of our addiction genes.This is where environment enters the picture.

Even if we carry the addiction genes and drink or use drugs on occasion, we may never become addicted to drugs or alcohol.Someone who has inherited the genes and grows up in a healthy environment with little or no exposure to drugs and alcohol, and who doesn’t experience any major traumatic life events, may never manifest the disease. Are they still genetically an addict or an alcoholic? Yes, they have those chromosomal traits.But the environment has not supported the disease’s development.

Conversely, someone with very little genetic contribution—three or four generations without a case of addiction or alcoholism in his family—who grows up living over a bar in an inner city, next to a crack house, hanging out with a gang that’s manufacturing methamphetamine and amphetamine has a pretty good chance of developing the disease of addiction primarily because of his environment.

The disease of addiction is very patient.Many who have had this type of euphoric experience with drugs or alcohol go through long periods of training, schooling, and employment where outside factors keep their disease at bay.The same people who say they will never drink before 5:00p.m., or will never have a drink at lunchtime, may find that when their life circumstances change due to financial difficulties, job loss, or the death of a spouse, the floodgates suddenly open.Even retirement can be a trigger:More and more people of retirement age find that their drinking or drugging patters change dramatically when the structure and constraints of their work life are no longer present.

One way to trigger addiction is to experience stress.Stress causes the adrenal glands to release the hormone cortisol.The stress could be good or bad—marriages or funerals, births or deaths, letters from the lottery commission or letters from the tax collector it doesn’t really matter.All events of significance will stimulate the release of cortisol, which has the effect of raising the dopamine requirements in the person who has the addiction genes—1 in 10 people in the United States.

Once we establish high dopamine requirements, normal pleasures—a day with the kids, a beautiful sunrise, a painting, or good music—don’t seem to satisfy the midbrain’s requirements for reward.Something that has worked in the past, such as surge of dopamine from alcohol, cocaine, methamphetamine, or an opioid, may serve the purpose.

Our midbrain sends out cravings for the substance that it deems necessary for survival and the midbrain will require us to seek out the same substance, over and over and over again, until the cycle is broken.