***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Striatal D2 dopamine receptor characteristics of nine male patients with alcohol dependence abstinent for 1–68 weeks and eight healthy male volunteers were studied in vivo with positron emission tomography . The selective D2 receptor lig and [11C]raclopride and equilibrium model was used for D2 receptor density ( Bmax ) and affinity ( Kd ) measurements . A trend for a decreased striatal D2 receptor density and for reduced D2 receptor affinity was observed in patients with alcohol dependence . These parameters were not statistically significantly different between alcoholics and controls , but the ratio between D2 receptor density and affinity ( Bmax/Kd or the striatum/cerebellum ratio from the high specific activity scan ) was highly significantly lower in alcoholics than that of controls . In conclusion , the low D2 dopamine receptor Bmax/Kd ratio ( striatum/cerebellum ratio ) indicates that specific aspects of striatal [11C]raclopride binding in vivo are deviant in alcoholics compared to controls . The result is compatible with a reduced avidity of striatal dopamine D2 receptors in alcoholics , which is in line with the idea that D2 dopaminergic mechanisms are involved in the biology of alcohol dependence in man IMPORTANCE Increased glutamate levels in the right associative striatum have been described in patients during a first episode of psychosis . Whether this increase would persist after effective antipsychotic treatment is unknown . OBJECTIVES To compare the glutamate levels in  antipsychotic-naive patients with first-episode psychosis in the right associative striatum and right cerebellar cortex using proton magnetic resonance spectroscopy before and 4 weeks after antipsychotic treatment and to compare these results with normative data from sex-matched healthy control subjects . DESIGN , SETTING , AND PARTICIPANTS Before-after trial in an inpatient psychiatric research unit among 24 antipsychotic-naive patients with first-episode psychosis and 18 healthy controls matched for age , sex , h and edness , and cigarette smoking . INTERVENTIONS Participants underwent 2 proton magnetic resonance spectroscopy studies : patients were imaged at baseline and after 4 weeks of antipsychotic treatment , while controls were imaged at baseline and at 4 weeks after the baseline measurement . Patients were treated with oral risperidone ( open label ) for 4 weeks with dosages that were titrated on the basis of clinical judgment . MAIN OUTCOMES AND MEASURES Glutamate levels were estimated using LCModel ( version 6.2 - 1 T ) and were corrected for the cerebrospinal fluid proportion within the voxel . RESULTS Patients with first-episode psychosis had higher levels of glutamate in the associative striatum and the cerebellum during the antipsychotic-naive condition compared with controls . After clinical ly effective antipsychotic treatment , glutamate levels significantly decreased in the associative striatum , with no significant change in the cerebellum . No differences in glutamate levels were observed between groups at 4 weeks . CONCLUSIONS AND RELEVANCE Increased glutamate levels observed at baseline in patients with first-episode psychosis normalized after 4 weeks of clinical ly effective antipsychotic treatment . These results provide support for the hypothesis that improvement in clinical symptoms might be related to a decrease in glutamate levels There is as yet no definite prognostic marker to determine whether a first-episode psychosis will become schizophrenia or not . The aim of the present study is to address whether the mechanism of sensitization of the subcortical dopaminergic pathway - yielding to an increase of the postsynaptic D2 receptors - may serve as a prognostic marker of clinical outcome in drug naïve patients with a first-episode psychosis , by means of a prospect i ve and multicentric study with untreated first-episode psychosis patients ( n=37 ) .  123I-IBZM SPECT was performed at the time of the inclusion in the study , before antipsychotic medication was initiated . One year later , patients were assessed again so as to determine their diagnosis . There was a significant group effect at baseline in D2 Striatal/Frontal ( S/F ) ratios ( F=10.2 , p<0.001 ) . Bonferroni posthoc comparisons attested significant differences between diagnosis ( p=0.006 ) , and between schizophrenia and control groups ( p<0.001 ) but no differences between non-schizophrenia and control groups ( p=0.9 ) . The logistic regression model showed that D2R binding ( p=0.02 ) and PAS ( Premorbid Adjustment Scale ) adulthood score ( p=0.03 ) were predictive of the final diagnosis ( schizophrenia/non-schizophrenia ; Nagelkerke R(2)=0.59 ; X(2)=11.08 , p=0.001 ) . These findings replicate previous results on the usefulness of D2R binding as an objective prognostic parameter , together with the evaluation of premorbid adjustment , of the evolution of first-episode psychosis . In this regard , the results may provide a new view in the approach of early and personalized treatment in the debut of a psychosis OBJECTIVE While there is robust evidence of elevated dopamine synthesis capacity once a psychotic disorder has developed , little is known about whether it is altered prior to the first episode of frank illness . The authors addressed this issue by measuring dopamine synthesis capacity in individuals at ultra-high risk of psychosis and then following them to determine their clinical outcome . METHOD This prospect i ve study included 30 patients who met st and ard criteria for being at ultra-high risk of psychosis and 29 healthy volunteers . Participants were scanned using [(18)F]6-fluoro-L-dopa positron emission tomography . The ultra-high-risk patients were scanned at presentation and followed up for at least 3 years to determine their clinical outcome . Six patients had comorbid schizotypal personality disorder and were excluded from the analysis ( data are provided for comparison ) . Of the remaining patients , nine developed a psychotic disorder ( psychotic transition group ) and 15 did not ( nontransition group ) . RESULTS There was a significant effect of group on striatal dopamine synthesis capacity . The psychotic transition group had greater dopamine synthesis capacity in the striatum ( effect size=1.18 ) and its associative subdivision ( effect size=1.24 ) than did the healthy comparison subjects and showed a positive correlation between dopamine synthesis capacity and symptom severity . Dopamine synthesis capacity was also significantly greater in the psychotic transition group than in the nontransition group . CONCLUSIONS These findings provide evidence that the onset of frank psychosis is preceded by presynaptic dopaminergic dysfunction . Further research is needed to determine the specificity of elevated dopamine synthesis capacity to particular psychotic disorders 
    Output:
    
The review provides evidence for abnormal dopaminergic , GABAergic , and glutamatergic neurotransmission in antipsychotic-naive/free patients with schizophrenia compared with healthy controls .
The review concludes with a model illustrating how these abnormalities could lead to impaired LTP in patients with schizophrenia and consequently cognitive deficits