Modulation of auditory and visual processing by delta-9-tetrahydrocannabinol and cannabidiol: an FMRI study.

Although the effects of cannabis on perception are well documented, little is known about their neural basis or how these may contribute to the formation of psychotic symptoms. We used functional magnetic resonance imaging (fMRI) to assess the effects of Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) during visual and auditory processing in healthy volunteers. In total, 14 healthy volunteers were scanned on three occasions. Identical 10 mg THC, 600 mg CBD, and placebo capsules were allocated in a balanced double-blinded pseudo-randomized crossover design. Plasma levels of each substance, physiological parameters, and measures of psychopathology were taken at baseline and at regular intervals following ingestion of substances. Volunteers listened passively to words read and viewed a radial visual checkerboard in alternating blocks during fMRI scanning. Administration of THC was associated with increases in anxiety, intoxication, and positive psychotic symptoms, whereas CBD had no significant symptomatic effects. THC decreased activation relative to placebo in bilateral temporal cortices during auditory processing, and increased and decreased activation in different visual areas during visual processing. CBD was associated with activation in right temporal cortex during auditory processing, and when contrasted, THC and CBD had opposite effects in the right posterior superior temporal gyrus, the right-sided homolog to Wernicke's area. Moreover, the attenuation of activation in this area (maximum 61, -15, -2) by THC during auditory processing was correlated with its acute effect on psychotic symptoms. Single doses of THC and CBD differently modulate brain function in areas that process auditory and visual stimuli and relate to induced psychotic symptoms.

Neuroanatomical differences between familial and sporadic schizophrenia and their parents: an optimized voxel-based morphometry study.

Symptomatic differences have been reported between patients with familial and sporadic schizophrenia. The present study examined neuroanatomical differences between the two subgroups and their parents using voxel-based morphometry. High-resolution T1-weighted images were obtained using 3 Tesla magnetic resonance imaging from 20 patients with schizophrenia (familial subgroup, n=10; sporadic subgroup, n=10), 20 of their parents (familial subgroup, n=10; sporadic subgroup, n=10) and 20 healthy volunteers. Gray matter density (GMD) was compared between groups on a voxel-by-voxel basis. Compared with the sporadic patients, the familial patients had significantly reduced GMD in the thalamus bilaterally. Reduction of GMD in bilateral thalami was also found in familial parents in comparison with sporadic parents. Compared with controls, both familial and sporadic patients had lower GMD involving bilateral insula, right temporal lobe, right occipital lobe, left lenticular nucleus and right cerebellum. However, only familial patients showed lower GMD than controls in the right thalamus. Compared with controls, only familial parents showed lower GMD in the right insula extending to the right temporal lobe and the right parietal lobule. The present data suggest that familial schizophrenia is associated with more severe structural abnormalities than sporadic schizophrenia, especially in the thalamus.