Abstract
New-onset schizophrenia patients who continue to use cannabis after hospital treatment have been found to have more positive symptoms and a more severe illness at follow up [1]. Patients diagnosed with schizophrenia use cannabis for the same reasons as the general population, for the induction of euphoria, somnolence and altered perception. While some believe that patients are especially prone to self-medicate with cannabis to reduce or alter delusions, hallucinations and anxiety [2], the evidence for self-medication is limited. In particular, the use of cannabis to alleviate discomfort in individuals prone to psychosis is somewhat puzzling because cannabis tends to increase delusional and hallucinatory phenomena [3]. Moreover, most patients, when presenting for treatment of psychosis, describe such phenomena as distressing.
For some patients the answer to this puzzle may lie in the fact that cannabis use alters the content of psychosis toward more positive themes, congruent with the relaxation, euphoria, and enhanced sense of self-efficacy brought about by the drug. Religious enlightenment, enhancement of the intellect to genius level, special mental powers, or protection from threatening forces are common themes. The association of increased psychosis with drug euphoria may lead to a formed delusional system in which the drug itself is believed to be a conduit for positive supernormal experiences.
Over time the patient may develop a persisting, cannabis-oriented delusional system that persists at baseline or is easily reactivated by further episodes of cannabis-induced psychosis. Interviews with such patients show that they often do perceive that the drug provokes hallucinations and delusions. However, if the drug reliably produces grandiose delusions and associated self-affirming hallucinatory experiences, in association with relief from negative affective experience, then the psychosis itself may be sought out by patients as desirable. As such, these delusional constructs pose special challenges in the treatment of substance abuse and psychosis. The following clinical vignettes illustrate the phenomena of drug-oriented delusions.
Case Reports
Patient 1
A 29-year-old man with a history of substance abuse and psychosis presented to the acute inpatient psychiatric department at James Fletcher Hospital, Newcastle, New South Wales, for treatment. On the first admission his delusions were noted to be bizarre and more characteristic of schizophrenia, yet a diagnosis of substance-induced psychosis was given. His primary delusion was that his brain was a computer that was being programmed by outside forces. Television was often involved. A show about space travel led him to believe that a program for space vehicle design had been inserted into his brain. He also believed that others had been programmed and he was suspicious of them. He experienced voices that instructed him to kill himself to escape the thought control and messages, and other voices with a contrary message. He was a regular cannabis smoker. After discharge from his first admission he had resumed cannabis use and did not take prescribed medication.
He was distressed by his symptoms. He did not experience medication as helpful but he felt that cannabis was, noting that even at his worst he could watch TV after smoking cannabis without the same intensity of delusional experience. He described his use thus:
‘When I smoke it's like a thick cloud, a smoke screen that protects my mind from the messages getting through. Some get through, but less. It's like the cloud cover that blocks the sunlight that makes things grow. My mind is foggy, and it's harder for them to get in.’
After 2 weeks of risperidone his delusional ideation, paranoia and auditory hallucinations receded. He lacked any insight into the role of risperidone in his recovery. He did not associate cannabis abstinence with recovery either. He continued to feel that cannabis had played a protective role for him during his paranoid illness and would be able to do so if he became psychotic again.
Patient 2
A 23-year-old man with a history of bipolar disorder that pre-dated the onset of cannabis use was admitted to James Fletcher Hospital for management of a particularly severe manic episode. There was reliable collateral history that the patient had begun using cannabis regularly only 12 months prior to the index admission. His family were highly religious and opposed to substance abuse; but they supported the patient in many of his more extreme religious views.
At the time of presentation he was floridly psychotic with several grandiose delusions. He described cannabis as a ‘gift from God’ because he would experience an intensification of hearing God's voice and a heightened sense of enlightenment while intoxicated. As his mania resolved he incorporated the treatment message to not use cannabis into his delusional system, but he continued to believe that cannabis offered a connection with God and that God would allow His followers to smoke cannabis after the day of reckoning.
Patient 3
This patient was a 24-year-old man with a diagnosis of chronic paranoid schizophrenia and a history of an elaborate, treatment-resistant delusional system. The primary delusional construct was that he was a god or demigod on a mission to rid the world of evil. He was a regular user of cannabis and frequent user of amphetamines. In the past his delusions had motivated him to assault people whom he believed to be demons. Despite months of forensic psychiatric care and abstinence from illicit substances, there was little recorded improvement in his delusional system.
He was admitted to James Fletcher Hospital, with a relapse of his severe psychosis brought about by non-compliance with depot risperidone and olanzapine and resumption of cannabis use. Cannabis had a prominent role in his delusional system. He heard the voices of gods, which were intimidating and made him feel unworthy, and experienced the use of cannabis as causing the voices to change in character. When he smoked cannabis, they became ‘just humans’, which made him feel powerful and superhuman. The emotional high of the drug was, for him, a change from being human to a more powerful superhuman creature. This change was not only pleasant, but he believed that it was important to help him perform his task of fighting evil.
Many patients with psychotic illness are never completely free from auditory hallucinations or delusional ideas. The cases described here suggest that a subset of patients with residual delusions and hallucinations may remain motivated to use cannabis because it has induced positive, mood-congruent psychotic experiences that remain incorporated into a delusional system. This hypothesis may help to explain recent findings that 6 months after cognitive behavioural therapy (CBT)/motivational interviewing aimed at reducing drug use, patients diagnosed with schizophrenia and cannabis use showed no treatment effect, whereas alcohol and amphetamine users did [4].
In a subset of patients, cannabis appears to become uniquely integrated into their psychosis. The author feels that it may be worthwhile to further evaluate the use of CBT in this population, but it may be that CBT focusing primarily on substance abuse behaviours is not enough. CBT has been found to be effective in the management of positive symptoms of schizophrenia [5]. Dually diagnosed patients with a primary psychotic disorder and drug-related delusions might benefit from CBT that preferentially addresses the drug-related delusional content.