CANNABIS AND SCHIZOPHRENIA A Longitudinal Study of Swedish Conscripts

899

678

Recent advances in the understanding of brain cannabinoid receptor function have renewed interest in the association between cannabinoid compounds and psychosis. In a 3-day, double-blind, randomized, and counterbalanced study, the behavioral, cognitive, and endocrine effects of 0, 2.5, and 5 mg intravenous delta-9-tetrahydrocannabinol (D-9-THC) were characterized in 22 healthy individuals, who had been exposed to cannabis but had never been diagnosed with a cannabis abuse disorder. Prospective safety data at 1, 3, and 6 months poststudy was also collected. D-9-THC (1) produced schizophrenia-like positive and negative symptoms; (2) altered perception; (3) increased anxiety; (4) produced euphoria; (5) disrupted immediate and delayed word recall, sparing recognition recall; (6) impaired performance on tests of distractibility, verbal fluency, and working memory (7) did not impair orientation; (8) increased plasma cortisol. These data indicate that D-9-THC produces a broad range of transient symptoms, behaviors, and cognitive deficits in healthy individuals that resemble some aspects of endogenous psychoses. These data warrant further study of whether brain cannabinoid receptor function contributes to the pathophysiology of psychotic disorders.

Section: Discussionmentioning

confidence: 51%

The Psychotomimetic Effects of Intravenous Delta-9-Tetrahydrocannabinol in Healthy Individuals: Implications for Psychosis

D’Souza

Perry

MacDougall

et al. 2004

899

678

“…A range of other studies have also implicated deficits of GABA A in schizophrenia (Lewis and Hashimoto, 2007). This is particularly relevant as cannabis can precipitate a psychotic episode in individuals who are predisposed to develop schizophrenia (Andreasson et al, 1987;Hambrecht and Hafner, 2000). Additionally, there are also extremely high rates of cannabis abuse among patients with schizophrenia, and this abuse often worsens outcomes (Hall and Degenhardt, 2000;Bersani et al, 2002;Rehman and Farooq, 2007).…”

Section: Discussionmentioning

confidence: 96%

A Transcranial Magnetic Stimulation Study of the Effects of Cannabis Use on Motor Cortical Inhibition and Excitability

Fitzgerald

Williams

Daskalakis

2009

Active compounds in cannabis such as tetrahydrocannabinol (THC) interact with the inhibitory neurotransmitter d-aminobutyric acid (GABA) but little is known about the functional effects of cannabis on human cortical brain processes. Therefore, the aim of the study was to investigate whether patients with chronic cannabis use demonstrate abnormalities in cortical inhibition or excitability. In all, 42 chronic cannabis using subjects (divided into heavy and light using subjects) and 19 controls were included in the study. Single and paired pulse transcranial magnetic stimulation were used to assess a number of parameters of cortical inhibition and cortical excitability. In addition, psychomotor function and THC plasma levels were measured. Both cannabis using groups (heavy and light use) demonstrated a reduction in short interval cortical inhibition compared with healthy controls, but there was no difference in other measures of cortical inhibition or cortical excitability. There was also no difference between the two groups on measures of psychomotor performance. Chronic cannabis use is associated with a reduction in cortical inhibition potentially related to activity at the GABA A receptors. Further research is required to explore whether this results from chronic cannabis use or reflects an underlying predisposition to developing chronic substance use problems.

“…Furthermore, cross-sensitization between D 9 -THC and stress have been recently reported in animals (Suplita et al, 2008), suggesting that the putative physiological and psychological effects of cannabis could be potentiated in individuals experiencing adverse environmental stress. Epidemiologically, cannabis use at a young age (Andreasson et al, 1987;Moore et al, 2007) and early experience of adverse (stressful) life events have been associated with increased risk of developing schizophrenia (Read et al, 2005), implicating cannabis use and sensitivity to stress as risk factors for psychiatric disorders, particularly schizophrenia. Despite the wealth of research suggesting a strong relationship between stress response and substance use disorders (Robinson and Berridge, 2000), no studies have directly investigated the relationship between the neurochemical response to stress and chronic cannabis use.…”

Section: Introductionmentioning

confidence: 99%

Dopamine Response to Psychosocial Stress in Chronic Cannabis Users: A PET Study With [11C]-(+)-PHNO

Mizrahi

Suridjan

Kenk

et al. 2012

A number of addictions have been linked with decreased striatal dopamine (DA) receptor availability and DA release. Stress has a key role in cannabis craving, as well as in modulation of dopaminergic signaling. The present study aimed to assess DA release in response to a laboratory stress task with [ 11 C]-( þ )-PHNO positron emission tomography in cannabis users (CU). Thirteen healthy CU and 12 healthy volunteers (HV) were scanned during a sensorimotor control task (SMCT) and under a stress condition using the validated Montreal imaging stress task (MIST). The simplified reference tissue model (SRTM) was used to obtain binding potential (BP ND ) in striatal subdivisions: limbic striatum (LST), associative striatum (AST), and sensorimotor striatum (SMST). Stress-induced DA release (indexed as a percentage of reduction in , with no effect in any other brain region. In conclusion, despite an increase in striatal BP ND observed during the control task, chronic cannabis use is not associated with alterations in stress-induced DA release.