ABSTRACT
BACKGROUND: Cannabis has been associated with transient psychotic states; however, the causal relationship between cannabis and schizophrenia continues to remain a matter of debate. Epidemiological and some biological studies hint at cannabis being an independent risk factor for schizophrenia; this has not been definitively proved. AIMS: We aimed to understand the patterns of glucose uptake in important brain regions among individuals with cannabis dependence and schizophrenia. Furthermore, we compared the interregional metabolic rates in pertinent neural circuits among individuals with cannabis dependence, schizophrenia and normal controls. SETTING AND DESIGN: This is a case-control cross-sectional study that was carried out by a general psychiatry department in collaboration with a nuclear diagnosis unit. MATERIALS AND METHODS: Male volunteers with cannabis dependence, schizophrenia and normal controls underwent FDG PET scanning. Glucose uptakes in pre-selected regions of interest were compared using MANOVA. Finally, Chow tests were used to compare interregional metabolic relationships in the mesocortical and cortical-subcortical-cerebellum circuits. RESULTS: Significant differences (P<0.05) were noted among individuals with cannabis dependence and schizophrenia in the medial and lateral temporal regions. When the neural circuits were compared, significant interregional differences (P<0.05) were noted between individuals with cannabis dependence and normal controls. However, among individuals with cannabis dependence and schizophrenia, no significant differences (P>0.05) were noted in these patterns. CONCLUSIONS: Our findings suggest that cannabis dependence can alter interregional relationships in a manner similar to schizophrenia. This indicates that cannabis could potentially play a role in the development of psychosis by altering neural circuits.
ABSTRACT
BACKGROUND: The effects of cannabis consumption on neurophysiological function have been a matter of considerable debate. With the legalization of medical marijuana, understanding the consequences of cannabis dependence has become extremely important. AIM: We attempted to understand the influence of cannabis on cerebral glucose metabolism in certain predetermined regions of interest (ROIs). Furthermore, we also explored inter-regional metabolic relationships between ROIs forming the "addiction" and "cognitive dysmetria" circuit. MATERIALS AND METHODS: 2-fluoro, 2-deoxy-glucose positron emission tomography (FDG PET) scans were carried out in 16 male patients (age: 25.3±10.38 years) with cannabis dependence, 8-12 hours after the last cannabis consumption. Resting glucose uptake in 14 pre-determined ROIs was compared with glucose uptake in 16 non-drug using volunteers (age: 29.2±8.39 years). RESULTS: The two groups differed in their lateral and medial temporal glucose uptakes by approximately 16-24%. The relationships between inter-regional glucose uptakes in the two circuits were compared using the Chow Test. Significant differences in inter-regional correlations in the medial temporo-frontal and parieto-thalamic were noted between the two groups. CONCLUSION: The altered metabolic relationships among various brain regions can have potentially important implications for understanding cannabis dependence and cannabis-induced psychopathology.
