Prescriptions for opioid painkillers have risen by a staggering 300 percent over the past 10 years.¹ This drastic increase in the number of opioid prescriptions written and dispensed is thought to play a major role in the global problem of addiction to opioids such as heroin, morphine, and prescription pain relievers.

In the U.S. alone, 2.1 million people suffer from substance use disorders related to prescription opioid pain relievers, while an estimated 467,000 are addicted to heroin.² Prescription pain relievers are considered a “gateway drug” to heroin. Over the past five years, heroin deaths have increased by 45 percent.

This increase is blamed on the rise of addictive prescription drugs such as Vicodin, OxyContin, Percocet, codeine, and Fentora, all of which are opioids. (The reason for the resurgence of heroin is in large part due to it being less expensive and, sometimes, easier to obtain, than its prescription counterparts).

Despite the prevalence of the problem, why some people become addicted and others do not remains a mystery. It’s known, however, that such drugs lead to neuroplastic changes in animals when taken long term, and now new research shows they also occur in humans, even after short-term use.

One Month of Morphine May Change Your Brain

In a study by researchers at the University of Alabama at Birmingham, people with chronic low back pain received either morphine or a placebo daily for one month. Both groups experienced similar reductions in pain, but there was a major difference among those taking morphine — changes in the brain.

Magnetic resonance imaging (MRI) scans showed the patients taking morphine had a 3 percent reduction in gray matter volume over the course of the study. The reductions occurred in regions of the brain that regulate emotions, cravings and pain response.³

Further, the morphine group had increases in gray matter volume in areas related to learning, memory and executive function. Lead study author Joanne Lin told Reuters:⁴

“Because we are seeing that opioids rapidly change the brain, our take-home message is that opioids should be reserved for cases when most other treatment options have failed.”

A similar study published in 2011 also found daily morphine can cause neuroplastic changes in the human brain after only one month of use. According to that study:⁵

“Several brain regions underwent volumetric change over the morphine use period … Following the month of morphine administration, reduced gray matter was observed in the right amygdala.The amygdala, together with the hippocampus, drive reward-related learning processes via modulatory influences on the nucleus accumbens.

The amygdala is involved in drug-induced associative learning, drug craving, reinforcement, the development of dependence, and the experience of acute withdrawal.

Atrophy in the amygdala was found in a previous study to be an important area of morphologic difference distinguishing opioid-dependent individuals from healthy controls.

… Learning involving the amygdala may lead to long-term behavior patterns that continue even as pleasurable effects subside; perhaps forming the basis for opioid misuse in some individuals.”