A 28-year-old man suffering from delusions apparently triggered by cannabis use was hospitalized in Colombia last year after trying to kill a neighbour he believed was an impostor. In a case history recently published in the journal Cureus, the man had been abusing cannabis for eight years and reported developing a hostile relationship with his parents whom he also believed had been killed and replaced by impostors.
While the theme of having close family members being replaced with duplicates is pretty familiar to anyone who has seen movies such as Invasion of the Body Snatchers, cases of people experiencing this kind of delusion are hardly uncommon. Usually known as Capgras delusion, such cases are most often seen in schizophrenia but can occur due to brain injury or stroke as well. Though cases of actual violence linked to this kind of delusion are relatively rare, they do occur. For example, a Cornell University doctoral student murdered his wife in 2010, allegedly believing that she was an impostor. He then set fire to his apartment to conceal the crime and later attempted suicide. Despite attempts by his lawyer to have him found guilty by reason of insanity, he was eventually convicted of second-degree murder and denied an insanity appeal.
In the latest case, the man admitted to a Colombia hospital also suffered from delusions of grandeur along with his persistent belief that his parents were dead. He had no other history of mental illness and no apparent physical abnormalities except for the presence of cannabis in his system. After two months in hospital, he responded to treatment and was released fully recovered after his doctors decided that he no longer posed a risk to his parents or neighbours.
While cases of Capgras delusion linked to cannabis use have been reported in the past, usually in males between the ages of 17 and 30, they are still extremely rare. Patients with Capgras delusions linked to schizophrenia usually recover fairly quickly after being treated with antipsychotic medication though cases still vary depending on the actual cause.
Though it seems unlikely that the rising acceptance of cannabis will lead to more such cases, more research is definitely needed for the future.
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