Cerebral glucose metabolism and D2/D3 receptor availability in young adults with cannabis dependence measured with positron emission tomography.

INTRODUCTION: Cannabis users have been reported to have decreased regional cerebral glucose metabolism after short periods of abstinence. The purpose of this study was to measure striatal dopamine receptor (D2/D3) availability and cerebral glucose metabolism with positron emission tomography (PET) in young adults who had a prolonged exposure to cannabis and who had been abstinent for a period of at least 12 weeks. MATERIALS AND METHODS: Six 18-21-year-old male subjects with cannabis dependence in early full remission and six age- and sex-matched healthy subjects underwent PET scans for D2/D3 receptor availability measured with [C11]-raclopride and glucose metabolism measured with [18F]-FDG. All subjects were sober for at least 12 weeks before PET scan procedures. PET data were analyzed with statistical parametric mapping software (SPM99; uncorrected p < 0.001, corrected p < 0.05 at the cluster level). Toxicology screening was performed prior to the PET scan to confirm the lack of drugs of abuse. OBSERVATION AND RESULTS: Striatal D2/D3 receptor availability did not differ significantly between groups. Compared to controls, subjects with cannabis dependence had lower normalized glucose metabolism in the right orbitofrontal cortex, putamen bilaterally, and precuneus. There were no significant correlations between striatal D2/D3 receptor availability and normalized glucose metabolism in any region of the frontal cortex or striatum. CONCLUSION: These findings may reflect both cannabis exposure and adaptive changes that occur after a prolonged period of abstinence. Subsequent studies should address whether metabolic and dopamine receptor effects are associated with either active use or longer-term withdrawal in these relatively young subjects.

Iowa gambling task in schizophrenia: a review and new data in patients with schizophrenia and co-occurring cannabis use disorders.

BACKGROUND: We reviewed previous studies comparing schizophrenia patients and healthy subjects for performance on the Iowa Gambling Task (IGT) (a laboratory task designed to measure emotion-based decision-making), and found mixed results. We hypothesize that deficits in IGT performance in schizophrenia may be more specifically related to concurrent substance use disorders. To test this hypothesis, we compared schizophrenia patients with (SCZ((+))) or without (SCZ((-))) cannabis use disorders, to healthy subjects, on measures of cognition and IGT performance. METHODS: A comprehensive battery of cognitive tests and the IGT were administered to three groups of subjects: (1) 13 subjects with DSM-IV diagnosis of schizophrenia and no concurrent substance use disorders (mean age: 28+/-12 (SD); 54% males); (2) 14 subjects with schizophrenia and concurrent cannabis use disorders (mean age: 29+/-9 (SD); 71% males); and (3) 20 healthy subjects (mean age 33+/-10 (SD); 60% males). RESULTS: Compared to the healthy group, both schizophrenia groups were cognitively more impaired, and did worse on IGT performance. There were no differences between SCZ((+)) and SCZ((-)) patients on most of the cognitive tests, and IGT performance. CONCLUSIONS: Schizophrenia patients show widespread impairments in several cognitive domains and emotion-based decision-making. These results are consistent with the evidence that schizophrenia reflects a dorsolateral and orbitofrontal/ventromedial prefrontal cortex dysfunction. More intriguing, it appears that the concurrent abuse of cannabis has no compounding effects on cognition, as well as emotion/affect-based decision-making.

Quantitative craniofacial anomalies in a racially mixed schizophrenia sample.

BACKGROUND: The observation that some patients with schizophrenia display subtly anomalous craniofacial features dates back to the early 1900s and has recently been hypothesized to reflect disrupted prenatal development also involving the brain. Most studies to date have used observer ratings rather than physical measurements and have studied only Caucasian samples. Our objective was to determine whether schizophrenia is associated with craniofacial anomalies applying quantitative methods in Caucasian and African American subjects. METHODS: Participants were 32 Caucasian and 20 African American outpatients aged 18 to 60, meeting Structured Clinical Interview for DSM-IV (SCID) confirmed criteria for schizophrenia/schizoaffective disorder, recently discharged from a psychiatric hospital in Queens, New York. The healthy control subjects were recruited through local advertisements and were individually matched to the patient sample on gender, race, and age. RESULTS: Thirty-two measurements of the head and face reflecting all regions of potential developmental significance were taken according to published methods and validated for this study. Significantly greater skull base width [F(1,51) = 13.11, p = .0005] and greater height of the cutaneous lower lip [F(1,51) = 7.90, p = .0059] were found among patients after applying multiplicity correction. Statistical correction for group differences in body weight did not alter the findings. CONCLUSIONS: Findings agree with the two major anthropometric studies in schizophrenia.