(dailyRx News) Methadone has been used to treat heroin addiction since the 1960s. While keeping people off heroin is a good thing, methadone can hurt learning and memory function.
Two recent studies tested methadone on brain function. Results showed that brain cells could still grow, but learning, attention span and memory function were very much reduced.
Jannike M. Andersen, researcher in the division of forensic toxicology and drug abuse at the Norwegian Institute of Public Health, and Amelia J. Eisch, PhD, professor of psychiatry at University of Texas Southwestern Medical Center, worked together on two studies to test the long-term effects of methadone on the brain.
Researchers gave a group of rats methadone injections for three weeks.
They were looking for the problems with learning and memory, and the function of the attention span.
For the first part of the experiment, they gave the rats new toys to play with to see if the methadone affected their attention spans.
Then researchers tried giving the rats new toys after a full day off of methadone to see if their attention spans would recover with the drug out of their systems.
Results of the attention span experiment showed that while on methadone and a day after quitting methadone, the rats had reduced attention spans.
Andersen said, “The fact that the attention is impaired even after the drug was no longer present in the body suggested that methadone causes changes in brain cells.”
“We do not yet know exactly what the changes are and how long-lasting they will be.”
Researchers then took samples of the hippocampal region of the rats’ brains one hour, one day and one week after ending methadone injections.
They tested the rats’ brains for a particular protein that acts as a signal molecule involved with learning and memory function.
Results showed that one day after quitting methadone injections the protein in the hippocampal region of the brain was reduced by 70 percent.
Scientists compared their results to morphine experiments and determined they were very similar.
The experiment led by Dr. Eisch determined that methadone did not effect the actual cell growth in the hippocampal region of the rats’ brains.
Further research will be necessary to fully understand the effects of long-term methadone use on the brain.
Authors said for ethical reasons testing would not be possible on humans, except for surveys of existing or former methadone users. Which would not provide well-controlled, reliable data.
The first study was published in February in the Journal of Pharmacy and Pharmacology, and the second study was published in May in Neuroscience Letters. Funding for this project was provided by the Norwegian Institute of Public Health, no conflicts of interest were found.