Many people are reluctant to get help because they are embarrassed by or even ashamed of their addiction. They feel that if only they had enough self-control, they would not have a problem.

But addiction is a brain disease. Although alcohol and different drugs that are abused have specific brain effects, they all share common pathways deep in the brain.

When a person ingests alcohol or another mind-altering drug, these substances imitate the brain’s natural neurotransmitters and overstimulate the neural circuits that control rewards.

During alcohol or drug use, dopamine floods the brain. This important neurotransmitter is located in brain regions that control thinking, motivation, movement, and feelings of pleasure.

When users ingest a mind-altering substance, dopamine rushes into their brains and they experience a temporary euphoria.

After repeated episodes of alcohol or drug use, the brain adjusts by producing less dopamine or by decreasing the number of its dopamine receptors.

Consequently, alcohol or drug users do not feel much pleasure when they’re not using drugs or alcohol, and they need more of the mind-altering substances to get the same feeling they had before.

Another part of the brain in the frontal lobe, the anterior cingulate (which is responsible for decision-making and broader judgment) regresses when an addiction takes hold.

Helping patients overcome their addictions involves strengthening their anterior cingulate neural circuits to gain better control of the dopamine reward system, which encourages continued use despite the problems it causes.

Research shows that chronic alcoholics have smaller hippocampus memory centers and more impaired cognitive abilities than non-addicts. How much alcohol it takes to affect these memory centers depends on a variety of factors.

Investigators at the University of California, San Francisco, reported that the presence of a particular variant of a gene known as BDNF (brain-derived neurotrophic factor) in alcoholics was associated with greater shrinkage of the hippocampus.

Research on chronic marijuana users has demonstrated changes to the amygdala, a region of the brain that controls emotion; and the nucleus accumbens, a region that plays an important role in processing positive stimuli and rewards.

Studies of numerous types of drugs, including alcohol, cocaine, and opiates, have demonstrated their effects on a variety of brain neurotransmitter systems aside from dopamine, such as serotonin and GABA receptors, which calm nerve activity.

In addition, chronic alcohol abuse is associated with poor nutrition, and can result in a deficiency of the B vitamin, thiamine. Nearly four out of five alcoholics develop thiamine deficiency, which can cause debilitating confusion and psychosis.