Meth abuse overdose effects are very similar to those seen after a traumatic brain injury, according to researchers who examined the effects of "club drugs" in rats.
"We showed that a single meth abuse overdose can be as damaging as a head-on motor vehicle collision in the brain," co-author Matthew Warren, of the University of Florida in Gainesville, told Reuters Health.
Methamphetamine is a highly addictive stimulant that is chemically related to amphetamine, but is more potent and more harmful to the central nervous system. Warren and his associates analyzed changes in the proteins in rodents' brains after traumatic injury and decided to investigate whether methamphetamine and MDMA, also known as Ecstasy, might cause similar changes.
MDMA is a psychoactive drug that is chemically similar to methamphetamine and the hallucinogen mescaline. The results of animal studies have also shown it has toxic effects on the nervous system. The researchers presented their findings at the Society for Neuroscience's conference in San Diego.
The researchers studied "cytoskeletal" proteins, which make up the cellular skeleton of the brain responsible for holding the organ together, Warren explained. About 12 percent of the proteins in an area of the rodents' brains known as the cortex showed the same changes after a meth abuse overdose and a traumatic brain injury. When the researchers looked at the effects of a MDMA overdose, they found damage in the hippocampus, the region of the brain involved in memory formation.
"This data and the previous 4 years of research suggest some drugs, especially methamphetamine, cause changes that are not readily reversible," principal investigator Dr. Mark Gold, at the University of Florida's McKnight Brain Institute, said in a press release. "Future research is necessary for us to determine when or if methamphetamine-related brain changes reverse themselves."
Additionally, a common antipsychotic chemical used in emergency rooms against meth abuse overdose has been found to damage neurons in those brain zones involved in regulating movement. The new findings were noticed in experiments on rats and point that only mixing the drug, haloperidol and methamphetamine causes the destructive effects, not each chemical by itself.
The research team at Boston University School of Medicine believes that the neuronal damage is due to an overstimulation by the amino acid glutamate, which poisons the cells through oversynthesis of the neurotransmitter gamma-aminobutyric acid (GABA).
"This work in laboratory animals raises immediate concerns that a standard treatment for a meth abuse overdose in humans might worsen drug abuse-related brain injuries," said Dr. William Carlezon, at Harvard's McLean Hospital, not involved in this research.
"A crucial next step is to determine how atypical antipsychotic medications would affect methamphetamine toxicity in the same model."
The lab rats were injected with either methamphetamine or a control saline solution over an interval of eight hours. When the rodents received haloperidol before and nearly halfway through the eight-hour period, the team counted an over 5 times rise in base levels of glutamate in the substantia nigra, the brain area linked to movement disorders, Huntington's disease being an example.
Two days after the injections, glutamate levels in the substantia nigra were double in methamphetamine-treated rats as in saline-treated ones. The high glutamate levels were connected to the death of GABA-containing cells in parts of the substantia nigra. This can render patients treated for a meth abuse overdose vulnerable to seizures and movement disorders, even if this research did not investigate movement specifically.