Addiction and chemical dependency are diseases of the human brain.
It is understood that our personalities, behaviors, and emotions directly correlate with the structure and chemicals, called neurotransmitters, that makeup the human brain. Drugs of abuse hijack these chemicals and change how they are released. This can cause major imbalances in the nervous system as the body adjusts to drug or alcohol abuse.
When a drug is stopped suddenly, a void is left in the chemical balance of the brain. There is often not enough chemicals being produced to account for the drug that is now absent from the system. This means that the individual suffering from substance use disorder has now become dependent on the drugs, alcohol, or prescription medication.