title: Glutamate levels in the associative striatum before and after 4 weeks of antipsychotic treatment in first-episode psychosis: a longitudinal proton magnetic resonance spectroscopy study.
abstract: OBJECTIVE
  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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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, handedness, and cigarette smoking.
  
  
  METHODS
  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.
  
  
  METHODS
  Glutamate levels were estimated using LCModel (version 6.2-1T) 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 clinically 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
  Increased glutamate levels observed at baseline in patients with first-episode psychosis normalized after 4 weeks of clinically effective antipsychotic treatment. These results provide support for the hypothesis that improvement in clinical symptoms might be related to a decrease in glutamate levels.
authors: Laboratory of Experimental Psychiatry, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico2Neuropsychiatry Department, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico.
authors: Camilo
authors: C
authors: de la Fuente-Sandoval
authors: Pablo
authors: P
authors: León-Ortiz
authors: Mariana
authors: M
authors: Azcárraga
authors: Sylvana
authors: S
authors: Stephano
authors: Rafael
authors: R
authors: Favila
authors: Leonardo
authors: L
authors: Díaz-Galvis
authors: Patricia
authors: P
authors: Alvarado-Alanis
authors: Jesús
authors: J
authors: Ramírez-Bermúdez
authors: Ariel
authors: A
authors: Graff-Guerrero
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002525:Cerebellar Cortex / Q000187:drug effects / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D059907:Functional Neuroimaging; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism*; D018967:Risperidone / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D014150:Antipsychotic Agents; D018698:Glutamic Acid; D018967:Risperidone
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