Table 6.

In vivo brain PET imaging endocannabinoids in psychotic disorders.

Condition & treatment	n (cases/controls)	1Radioligand	Result	Primary regions of interest	Greater symptom severity	Reference
Untreated
First-episode psychosis	20/20	[11C]MePPEP	↓CB1	Hipp, striatum, ACC, thalamus	↓CB1	Borgan et al., 2019
Schizophrenia	16/12	[18F]-MK-9470	↑CB1	SF, IF, TC, MTL, PC, OC, insula, CC, putamen, caudate nucleus, NAc,, thalamus, Cb	↓CB1	Ceccarini et al., 2013
Schizophrenia	27/36	[11C]CURB	n.s. FAAH	Hipp, amygdala, LST, AST, SMST, ACC, mPFC, DLPFC	↓FAAH	Watts et al., 2020
Mixed(treated & untreated)
Schizophrenia	25/18	[11C]-OMAR	↓CB1	amygdala, caudate, Cb, cingulum anterior, cingulum posterior, FL, hipp, hypothalamus, insula, OC, pallidum, PC, putamen, TC, thalamus	↑CB1	Ranganathan et al., 2016
Treated
First-episode psychosis	7/11	[18F]FMPEP-d2	↓CB1	Hipp, striatum, ACC, thalamus	-	Borgan et al., 2019
Schizophrenia	51/12	[18F]-MK-9470	↑CB1	SF, IF, TC, MTL, PC, OC, insula, CC, putamen, caudate nucleus, NAc,, thalamus, Cb	n.s.	Ceccarini et al., 2013
Schizophrenia	9/10	[11C]-OMAR	↑CB1 (pons only)	FL, cingulate, hipp, putamen, globus pallidus, Cb, pons	↑CB1*	Wong et al., 2010

↑: higher, ↓: lower; n.s.: no significant difference from controls; -: no available data

CB1: cannabinoid CB1 receptor; FAAH: fatty acid amide hydrolase; Hipp: hippocampus; ACC: anterior cingulate cortex; SF: superior frontal; IF: inferior frontal; TC: temporal cortex, MTL: mesotemporal lobe; PC: parietal cortex; OC: occipital cortex; CC: cingulate cortex; NAc: nucleus accumbens; Cb: cerebellum; LST: limbic striatum; AST: associative striatum; SMST: sensory motor striatum; mPFC: medial prefrontal cortex; DLPFC: dorsolateral prefrontal cortex; FL: Frontal lobe.

¹CB1 receptor radioligand: [¹¹C]MePPEP, [¹⁸F]-MK-9470, [¹¹C]-OMAR and [¹⁸F]FMPEP-d2; FAAH radioligand: [¹¹C]CURB.

^*a ratio of positive and negative symptoms, not a direct measure from scale