Research has shown that there is an increased risk of psychotic episodes when certain drugs are used. Marijuana, for instance, has been linked with an increased risk of psychosis. It is unclear, however, whether drugs consistently increase the risk of psychosis or if individuals with a history of psychosis are more likely to use drugs. In the case of methamphetamine use, the debate may be coming to a close. Despite anecdotal evidence that individuals with psychosis are more likely to use the drug, a research team has found that when methamphetamine is being actively used, instances of psychosis increase dramatically. Focusing on long-term methamphetamine users, the study by researchers at Australian National University in Canberra found that the symptoms of psychosis are five times more likely to develop during periods of use when compared with periods of abstinence. The symptoms examined by the team included hallucinations (increased risk in 51 percent of participants), suspiciousness (71 percent), and delusions (35 percent). The level of risk was positively correlated with drug use. The study\u2019s lead author, Rebecca McKetin, said participants experienced psychotic symptoms at a rate of about 10 percent when they were not actively using methamphetamine, compared with 48 percent when they were in a heavy use stage (at least 16 days of use). \u201cPeople describe being followed, spied on \u2013 they will take down the number plate of every car behind them, spend hours searching for bugging devices in their homes, and some won\u2019t leave the house because they think that people are waiting for them outside,\u201d\u00a0 McKetin said. In addition, in cases where alcohol or heavy marijuana use was present, 69 percent of participants experienced psychotic symptoms. The researchers included 278 meth users over the age of 16 and assessed psychotic symptoms both while the participants were using methamphetamine and while they were not. The participants all met criteria for meth dependence and had used the drug for a mean of 13.1 years. The majority of the participants administered the drug through injection. McKetin said the study showed that the psychotic symptoms were not due to pre-existing conditions; the study excluded people who had a known psychotic disorder, such as schizophrenia. It also revealed a strong relationship between using the drug and psychosis, with symptoms abating when people stopped using meth. Photo by Favelvis, Flickr.