FINDINGS
A study in mice led by UCLA researchers shows that removing chemical messengers in the brain that are involved in both wakefulness and addiction may make withdrawal from opioids easier and help prevent relapse.
BACKGROUND
In 2000, UCLA sleep researchers discovered that human narcolepsy – a condition where people are overwhelmed with daytime drowsiness and sudden attacks of sleep – was caused by a loss of roughly 90% of the 80,000 brain cells containing hypocretin (also called orexin), a chemical messenger important in the regulation of sleep and wakefulness. Typically, people with narcolepsy are treated with drugs that for most people would be highly addictive, but interestingly these patients show little, if any, signs of drug addiction or withdrawal themselves.
The lack of hypocretin-producing neurons and addiction seen in narcolepsy took on a different twist when nearly two decades later the researchers made the surprising discovery that the brains of people addicted to heroin (a commonly abused opioid) have, on average, 54% more hypocretin-producing neurons than people who don’t have a substance abuse disorder – and confirmed the same finding in mice. However, when they stopped the opioid treatment in the mice, they found that the increase in hypocretin remained, lasting as long as four weeks.
This finding suggested that continued elevated levels of hypocretin could play a role in drug cravings, and, at the same time, shed light on why narcoleptic patients with very few of these hypocretin-producing neurons show little, if any, signs of addiction.
While studies in people are needed to confirm these findings, taken together, they suggest that developing drugs that target the hypocretin system may help treat addiction.
