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: Schizophrenia has been associated with a plethora of metabolic changes in the brain that vary with duration and type of psychoses. Additionally, it has been observed that antipsychotics can further alter cerebral glucose metabolism. These changes resulting from antipsychotics have been postulated to be reflective of the duration and mechanism of action of the medication. AIMS: We aimed to examine the influence of antipsychotics on brain metabolism in individuals with schizophrenia in a naturalistic setting. SETTINGS AND DESIGN: A cross-sectional study was carried out by the psychiatry department of a tertiary care hospital in collaboration with the Radiation Medicine Centre. MATERIALS AND METHODS: Eighteen male patients with schizophrenia in different phases of treatment underwent an 18F-deoxyglucose positron emission tomography scan in a resting state 12 hours after the last dose of antipsychotic. STATISTICAL ANALYSIS: The types and duration of treatment were then compared with the regional glucose uptake in 14 predetermined regions of interest. The relative Uptake Values were further compared using SPSS 11.0. RESULTS: An immediate increase followed by a decrease in cortical uptake was noted while the basal ganglia uptake remained high, albeit with a decreasing trend. Typical antipsychotics were associated with lower frontal cortical and higher basal ganglia and cerebellar uptake as compared to atypical antipsychotics. CONCLUSION: The differential influence of the type and duration of antipsychotic on glucose uptake suggests a possible trend towards long-term side effects with typical medications that were not noted on clinical examination. This however needs to be confirmed with larger, controlled studies.
Subject(s)
Antipsychotic Agents/pharmacology , Brain/drug effects , Brain/metabolism , Schizophrenia/metabolism , Adult , Antipsychotic Agents/therapeutic use , Brain/diagnostic imaging , Cross-Sectional Studies , Fluorodeoxyglucose F18 , Humans , Male , Pilot Projects , Positron-Emission Tomography , Radiopharmaceuticals , Schizophrenia/drug therapySubject(s)
Chlorzoxazone/pharmacology , Fluorodeoxyglucose F18 , Muscle Relaxants, Central/pharmacology , Muscle, Skeletal/diagnostic imaging , Neuroectodermal Tumors, Primitive, Peripheral/diagnostic imaging , Positron-Emission Tomography , Radiopharmaceuticals , Soft Tissue Neoplasms/diagnostic imaging , Administration, Oral , Adult , Artifacts , Buttocks , Chlorzoxazone/administration & dosage , Female , Fluorodeoxyglucose F18/pharmacokinetics , Humans , Lumbosacral Region/diagnostic imaging , Muscle Relaxants, Central/administration & dosage , Muscle Relaxation/drug effects , Muscle, Skeletal/drug effects , Radiopharmaceuticals/pharmacokineticsABSTRACT
BACKGROUND: Recent technological advances have established beyond any doubt the biological nature of schizophrenia. Functional neuroimaging using FDG-PET forms an important technique in understanding the biological underpinnings of psychopathology of schizophrenia. METHODS: Eighteen male patients diagnosed as having schizophrenia and having active psychosis as determined by PANSS were subjected to FDG-PET scanning under resting conditions. The glucose uptake in selected regions of interest was studied across the spectrum of schizophrenia. RESULTS: Chronicity and severity of illness did not influence cerebral glucose metabolism. Participants with negative schizophrenia had significantly decreased metabolism in all regions of the brain as compared to the positive type. The positive syndrome of schizophrenia was associated with significantly increased glucose metabolism in the medial temporal regions, basal ganglia and left thalamic regions. Hypometabolism was also noted in the cerebellum. CONCLUSION: While a number of brain areas can be identified as potential causative regions and hypotheses regarding putative mechanisms can be formed, the considerable heterogeneity of schizophrenia poses a great challenge in the precise delineation of the disease process.
