Meth psychosis presents medical, legal challenges.(FORENSIC MEDICINE)
SEATTLE — Methamphetamine-induced psychosis is a challenging condition from both a medical and legal perspective, according to a panel of addiction specialists at the annual meeting of the American Academy of Psychiatry and the Law.
Its is a potent, highly addictive drug that is relatively cheap and easy to make, but "unfortunately, it is also very neurotoxic," said Dr. Mace Beckson, a forensic psychiatrist at the University of California, Los Angeles.
In addition, users of the drug often run into trouble with the law because some of its adverse effects, such as cognitive impairment, paranoia, and psychosis, may be associated with violent behavior. Originally, the drug and the problems associated with it were confined to the western United States and Hawaii, but they have now "spread eastward," he said.
Dr. David Y. Kan, a psychiatrist and substance abuse specialist at the University of California, San Francisco, said that acute methamphetamine psychosis occurs mainly with the use of high doses and that people may become psychotic after just one such incident.
Several risk factors for methamphetamine psychosis have been identified and include preexisting personality disorder (especially antisocial personality disorder), intravenous injection or smoking of the drug, abuse of other substances, previous psychosis, and brain injury.
"The psychosis of methamphetamine tends to be predominantly a positive-symptom psychosis," Dr. Kan noted. Negative symptoms such as alogia, abulia, and the inability to communicate or form thoughts are relatively rare, which helps differentiate it from schizophrenia. "If a person can tell a joke or can laugh at a joke, then they are probably methamphetamine psychotic" and not schizophrenic.
The psychosis typically begins 5-90 hours after starting use of methamphetamine. Users experience sudden hallucinations that are more often visual than auditory and generally in the presence of a clear sensorium. Psychotic users also have paranoid, reality-based delusions and ideas of reference, and are restless and agitated.
"Often, this is one of the few intoxications that includes management from the medical standpoint" with the administration of antipsychotics for the agitation, Dr. Kan noted.
When the psychotic symptoms persist or recur after drug use has stopped, the diagnosis shifts to chronic methamphetamine psychosis. "We make this call all the time, although it's not technically recognized by the DSM-IV," he commented.
Individuals with chronic psychosis often have acute, flashback-type episodes in response to psychosocial stressors, and may experience psychotic symptoms even if they take relatively low doses of methamphetamine. During the flashbacks, plasma levels of norepinephrine and lesser metabolites of dopamine are elevated, and that surge in norepinephrine resembles that in post-traumatic stress disorder, Dr. Kan said. "There may be a different mechanism at play [rather than] traditional dopaminergic models of psychosis."
The association of methamphetamine use with violence is highly controversial because most data come from the criminal justice system.
In the psychiatric evaluation of methamphetamine users, the occurrence of psychosis and violence is highly variable, depending on tolerance and dose. "Clinical history [and specific circumstances are] your best guide. Toxicology, especially blood levels [of the drug], is not terribly well correlated with psychosis," Dr. Kan noted.
Forensic psychiatrists must consider a number of questions that may affect the legal defense of individuals who have committed crimes in association with methamphetamine use, according to Dr. Joseph R. Simpson, a psychiatrist with the University of Southern California, Los Angeles.
One question from a legal standpoint is whether or not the person is competent to stand trial. Doubt about competence may be raised if defendants have persisting cognitive dysfunction or psychosis with delusions that impairs their ability to understand the proceedings or assist in their defense, he said.
A second question is whether the person was able to form the specific intent needed to carry out the crime. That becomes relevant for crimes that require action with a specific purpose in mind, such as burglary.
The third question relates to whether the person had diminished capacity at the time of the offense, which would signify a reduced ability to premeditate and plan the crime because of the drug use. "There are a fair number of jurisdictions in which this [defense] is still allowed," he noted, "but typically, it's used for very serious crimes, such as first-degree murder," and the aim is usually to get a reduced sentence instead of an acquittal.
A final question is whether the person is not guilty by reason of insanity. An insanity plea is usually not an option in the case of acute drug intoxication, Dr. Simpson said.
However, it might be an option in the case of chronic drug-related psychosis under the legal concept of settled insanity, which requires evidence that substance use caused a long-lasting psychosis that has persisted beyond the period of acute intoxication.
The use of settled insanity pleas has been controversial. "Some people say that if you accept settled insanity, then you are going to reward more severe drug users," and lighter users, who do not develop chronic psychosis, will get harsher sentences, he said.
Further complicating the issue is the uncertainty regarding the role of the drug use at that point.
"If someone is psychotic for years after they have stopped using drugs, [how do we know or not if they were] going to be schizophrenic anyway?" Dr. Simpson asked. "Can you ever tease that apart, and does it matter?"
The availability of the settled insanity defense varies by jurisdiction, and the wording of documents such as statutes and jury instructions suggests it remains a gray area in the legal world, he said. "It's a very complicated issue."
The panelists reported that they had no conflicts of interest in association with their presentations.
Copyright 2009 Gale, Cengage Learning. All rights reserved. Gale Group is a Thomson Corporation Company.
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