How Fentanyl Affects The Brain

What is Fentanyl?

Fentanyl is synthetic morphine. Fentanyl, heroin, morphine, and certain types of prescription pain medications all belong to the same class of opioid drugs.

Originally developed as a surgical anesthetic in the 1960s, fentanyl began to be used as a medication for severe pain management in the 1990s. The most common legal medical administration of fentanyl for pain management is by transdermal patch or sublingual spray.

Fentanyl can be 100 to 10,000 times more powerful than morphine, depending on how it is produced.

How Does Fentanyl Affect the Human Brain?

Fentanyl is designed to efficiently cross the blood-brain barrier, which results in an almost immediate analgesic (pain reduction), euphoric, and sedative effect.

The chemical structure of fentanyl allows it to cross the blood-brain barrier at 100x the rate of morphine. It is this combination of fast-acting effect and concentrated dosing that makes fentanyl an extremely powerful – and dangerous – narcotic.

Fentanyl Binds to Opioid Receptors Throughout the Brain & Body

Once inside the brain, fentanyl binds strongly to mu-opioid receptors in the spinal cord, brain stem, and areas of the brain involved with pain perception, motivation, learning, and reward processing:

As noted in this graphic, fentanyl overdose deaths are usually caused by activated opioid receptors in the brain stem that suppress or stop the breathing reflex. With the strong potency of fentanyl, risk of overdose death is very high when used outside of closely monitored medical purposes.

Fentanyl and other opioid drugs can essentially hijack the brain’s natural motivation and reward system, leading to a strong, maladaptive form of learning – commonly known as addiction or substance use disorder.

Opioid drugs recruit neuronal pathways and neurotransmitter systems in the brain that are necessary for motivation, learning, and reward. It is this “takeover” of the brain’s natural learning and reward centers by opioid drugs that cause an almost immediate addiction risk.

Chronic Opioid Use and Cognitive Impairment

Long term opioid therapy (> 3 months) can lead to cognitive impairment.

In a study that looked at patients with chronic low back pain, researchers found that the group of patients who used opioid medications for pain management performed significantly worse on cognitive testing relative to the pain management group that used non-opioid pain management methods.

Specifically, the opioid users had worse performance on cognitive speed of processing and working memory tests.

Next: Fentanyl Overdose Facts