Addiction: 50% Genetic and 50% Environmental

LAS VEGAS—Pain: “an unpleasant sensory and emotional experience associated with actual tissue damage or described in terms of such damage.” With that introduction, Sanford M. Silverman, MD, Medical Director of Comprehensive Pain Medicine, in Pompano Beach, Florida, provided a comprehensive overview of the neurobiology of pain and addiction. He identified pain and addiction as major diseases, reviewed the epidemiology of prescription abuse, and described the complications of opioid therapy.

Addiction is as old as humankind, with opioid/stimulant use and abuse dating to ancient Sumeria. However, “stunningly few chemicals are addictive,” he pointed out. Among the 30 million known chemical compounds, only 100 are addictive, including nicotine, alcohol, psychostimulants such as cocaine and amphetamines, opiates, cannabinoids, barbiturates, and benzodiazepines.

The definition of addiction has shifted between 2001 and 2011 to emphasize it is not synonymous with physical dependence but without a doubt is a brain disease that disrupts the mechanism responsible for generating, modulating and controlling cognitive, emotional, and social behavior. “In the past, patients with mental illnesses were shunned, isolated, and shipped to mental asylums,” he said. “Modern science has demonstrated that depression and schizophrenia are physical disorders of the brain affecting behavior and can be treated. Drug addiction alters the functioning of the brain and thus changes behavior and the mind and can be treated.”

Contributions to the disease of addiction are 50% genetic and 50% environmental; however, it is not biology vs environment; rather, “they act together to produce the addiction behavioral phenotype,” Dr. Silverman said. Risk factors for addiction include the agent, the environment, and the host (See Table). Substantial evidence suggests both environmental and social factors can influence neurobiological substrates of addiction.


Pain can remain undertreated due to several reasons related to addiction: fear of patient harm or regulatory, legal, or licensing penalties; addictive disorder; risk for addiction; and/or the diversion or misuse of medications. A survey of 979 physicians identified both lack of awareness in identifying prescription drug diversion or prescription drug abuse and addiction as well as inadequate risk management and inadequate treatment of patients with pain.

Dr. Silverman outlined certain assumptions made about prescribing opioids; that is, “a physician understands risks and management of addictive disease; persistent failure to treat addiction is poor medical practice; failure to prescribe opioids when indicated is also poor medical practice; and physicians traditionally receive little or no education about pain management or the treatment of addiction.”

Dr. Silverman also provided “essential definitions” clinicians need to understand in treating patients with pain: physical dependence, tolerance, pseudo-addiction, chemical coping,and pseudotolerance.