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Abuse of opiates such as heroin, methadone and morphine destroy brain cells, reducing attention span and memory. But new research shows there may be a way to regain some lost patience and recall.
Researchers from Uppsala University in Sweden report in Proceedings of the National Academy of Sciences USA that brain cells targeted for early death by continued opiate use may be salvaged by injections of synthetic human growth hormone (HGH). HGH is a chemical naturally secreted by the pituitary gland at the base of the brain that stimulates cell growth and reproduction. The scientists say their findings open the door to new ways to treat and prevent damage from abuse of opiates in addicts as well as patients undergoing chronic pain management.
Previous studies show that chronic opiate use can disrupt new cell growth (neurogenesis) in the hippocampus, a midbrain region implicated in short-term and so-called episodic memory (places, people and emotions linked to events). Growth hormones seem to keep neurogenesis moving smoothly until old age when levels drop, leading to less cell production and general memory decline. Elderly patients treated with synthetic growth hormones have experienced improved memory, says study co-author Fred Nyberg, a professor of pharmaceutical biosciences at Uppsala.
The scientists believe that opiates have the same effect as aging by blocking the formation of new nerve cells, but that HGH has the power to clear the pathways and get the process rolling again.
The team isolated developing nerve cells from a mouse fetus in petri dishes and bathed them in morphine for a week; they added synthetic growth hormone to some of the cultures. Their findings: cells exposed only to morphine began to die off, but those also infused with HGH persisted and, in some cases, increased.
"If this works in humans as it works on these cells, we will be able to correct the impairment in hippocampus function due to opiate use," Nyberg says. He notes that the team is currently studying the effects of growth hormone injections on a patient undergoing chronic pain management who has also experienced memory impairment.
"We have seen improvement at least during the treatment regimen," he says. "From the pilot study, it seems like this will work also in humans."
Nyberg also believes that treating memory function will lead to new therapies to combat drug addiction because memory is an important component of the brain's reward system, which underlies dependency.
Frank Vocci of the National Institute on Drug Abuse in Bethesda, Md., says he would like to see research extended to include the potential of HGH to stave off drug dependence. Although, he notes, "this memory component may not be related to the addiction."