Among long-term methamphetamine users, the risk of developing symptoms of psychosis is five times more likely during periods of use (compared to periods of abstinence), according to researchers from Australian National University in Canberra.
Psychosis symptoms included suspiciousness (71 percent), delusions or unusual thought content (35 percent), and hallucinations (51 percent). The risk was strongly linked to how often they used the drug.
“This translated into an increase of around 10 percent having psychotic symptoms in the past month when they were not using methamphetamine up to 48 percent when they were using it heavily, that is, for more than 16 days,” said lead author Rebecca McKetin, Ph.D., from Australian National University.
When meth was used in addition to heavy cannabis and alcohol use, the risk for psychotic symptoms increased to 69 percent.
According to McKetin, “methamphetamine is known to be associated with psychosis, but to what extent this relationship is due to preexisting psychosis among users of the drug is not clear.”
She added that she had conducted other research showing that meth users had higher rates of psychosis than the general population, “but people kept saying to me things like, ‘those people who go crazy on the drug, well, they were crazy beforehand. ”
“Despite the seemingly obvious link, which many people take for granted, I kept hearing from people who didn’t think that the drug itself could cause psychotic symptoms, and they tended to yield to the view that it was merely exacerbating or precipitating some kind of underlying mental health condition,” she said.
“The bottom line is that we didn’t know how much the drug was responsible for the high rates of psychosis among meth users and how much of this was because they are a high-risk group for psychotic symptoms.”
The study involved 278 methamphetamine users 16 years and older while they were, and were not, using the drug so that researchers could assess any potential contribution of meth to psychotic symptoms.
The mean age of the study participants was 31.7 years; 72 percent were male; 72 percent were single; and 78 percent were unemployed. All participants met DSM-IV criteria for meth dependence in the year before entering the study and had used the drug for a mean of 13.1 years. The majority (83 percent) had injected it.
The findings showed that meth users were far more likely to experience psychotic symptoms while taking the drug compared to when they were not taking the drug.
McKetin notes that psychosis is related to the increase in dopamine levels produced by methamphetamine intoxication.
“Dopamine plays a key role in the emergence of psychotic symptoms in people with psychotic disorders. Most antipsychotic drugs attenuate dopamine activity, and methamphetamine more generally affects monoamine regulation and can have neurotoxic effects both on dopamine and other neurotransmitter systems, and these changes may also play a role,” she said.
McKetin said that psychotic symptoms should be recognized as a serious and harmful side effect of methamphetamine use.
“I would like people to stop saying that people who go crazy on meth were crazy to start with. We need to have a better public health response to methamphetamine use to combat this harm, and the thing I would like most to see is the broader implementation of evidence-based interventions to help people reduce their methamphetamine use,” she said.
Source: JAMA Psychiatry