A systematic review of neuroimaging and acute cannabis exposure in age-of-risk for psychosis

Abstract

Acute exposure to cannabis has been associated with an array of cognitive alterations, increased risk for neuropsychiatric illness, and other neuropsychiatric sequelae including the emergence of acute psychotic symptoms. However, the brain alterations associating cannabis use and these behavioral and clinical phenotypes remains disputed. To this end, neuroimaging can be a powerful technique to non-invasively study the impact of cannabis exposure on brain structure and function in both humans and animal models. While chronic exposure studies provide insight into how use may be related to long-term outcomes, acute exposure may reveal interesting information regarding the immediate impact of use and abuse on brain circuits. Understanding these alterations could reveal the connection with symptom dimensions in neuropsychiatric disorders and, more specifically with psychosis. The purpose of the present review is to: 1) provide an update on the findings of pharmacological neuroimaging studies examining the effects of administered cannabinoids and 2) focus the discussion on studies that examine the sensitive window for the emergence of psychosis. Current literature indicates that cannabis exposure has varied effects on the brain, with the principal compounds in cannabis (delta-9-tetrahydrocannabinol and cannabidiol) altering activity across different brain regions. Importantly, we also discovered critical gaps in the literature, particularly regarding sex-dependent responses and long-term effects of chronic exposure. Certain networks often characterized as dysregulated in psychosis, like the default mode network and limbic system, were also impacted by THC exposure, identifying areas of particular interest for future work investigating the potential relationship between the two.

Chronic exposure to a synthetic cannabinoid alters cerebral brain metabolism and causes long-lasting behavioral deficits in adult mice

“…Neuroimaging studies in cannabis users showed a decreased brain metabolic activity in several brain regions after acute cannabis expose as well as after short periods of abstinence (Block et al 2000;Lundqvist et al 2001;Eldreth et al 2004;Sevy et al 2008;Cupo et al 2021). However, the cerebral metabolism pattern after long periods of abstinence has not been well studied.…”

Marijuana use in children: An update focusing on pediatric tetrahydrocannabinol and cannabidiol use

“…Further studies are needed to reconcile the neuroimaging with neuropsychological test performance. 50,58,59 Although yet unknown, neuropsychological tests may improve or recover with prolonged abstinence, as this has been observed in some studies but not others. 51,60 The age of onset of cannabis use, as well as frequency and duration of use likely all impact recoverability.…”

“…Although the poor neuropsychological functioning in association with cannabis use in children has been consistently proven, the literature has been inconsistent in demonstrating the negative impact of cannabis on neuroimaging. Further studies are needed to reconcile the neuroimaging with neuropsychological test performance 50,58,59 …”

The thalamus in psychosis spectrum disorder

“…Administering THC in otherwise healthy humans elicits key symptoms of PSD, including delusional thought content ( Kleinloog et al, 2014 ). Similar to both ketamine and LSD, THC also perturbs large-scale neural system organization, and reproduces thalamocortical dysconnectivity to some extent ( Camchong et al, 2017 ; Cupo et al, 2021 ).…”