Inclusion Criteria:

1. Patients must be age 6 -18 for the Non-MRS arm of the study, and age 6 or above for the MRS arm of the study.
2. If applicable, a parent or legal guardian or legal representatives of study subject must provide informed consent and sign an informed consent document.
3. Female patients of childbearing age must be either postmenopausal for at least one year, surgically incapable of childbearing, or effectively practicing an acceptable method of contraception (oral or parenteral hormonal contraceptives, intrauterine device; barrier and spermicide. Abstinence is not an acceptable method).
4. Female patients of child-bearing potential must have a negative pregnancy test to be performed at screening and baseline.
5. Patients must meet DSM-IV criteria for Asperger's Disorder. Other Axis I & II disorders excluded are listed below.
6. Patient must not have other serious, unstable illnesses and must be otherwise physically healthy on the basis of a physical examination, medical history, electrocardiogram and the results of blood biochemistry, hematology tests and a urinalysis.
7. Patient must have a negative urine drug screen with the exception of amphetamines if the patient is being treated with stimulants for four months or longer prior to entry.

Exclusion Criteria:

1. Patients who meet DSM-IV criteria for any psychotic disorder including schizophrenia, schizophreniform disorder, schizoaffective disorder, delusional disorder, brief psychotic disorder, shared psychotic disorder, psychotic disorder due to a general medical condition, substance-induced psychotic disorder,psychotic disorder not otherwise specified, major depression with psychotic features, or bipolar disorder.
2. Patients who meet DSM-IV criteria for schizoid, schizotypal, or paranoid personality disorder. Patients who meet DSM-IV criteria for autistic disorder or pervasive developmental disorder.
3. Claustrophobic patients and those otherwise unable to successfully complete the MRS procedure prior to baseline.
4. Patients who meet criteria for substance abuse or dependence within the past three months. (Nicotine and caffeine are exceptions).
5. Patients believed by the investigator to be at significant risk for suicidal or violent behavior during the course of the trial.
6. Female patients who are pregnant or nursing.
7. Patients with a known or suspected seizure disorder.
8. If the results of the serum ALT or AST are more than twice the upper limit of the central laboratory's reference range, the patient may not be enrolled. If the results of any other biochemistry, hematology or urinalysis tests are not within the central laboratory's reference ranges, the patient can be enrolled only on condition that the investigator judges that the deviations are not clinically significant. This should be clearly recorded on the laboratory report and in the source documents.
9. Patients with a history of neuroleptic malignant syndrome (NMS) or similar encephalopathic syndrome.
10. Patients who, by history, have received treatment with Risperdal or another neuroleptic (including olanzapine or quetiapine) within three months of baseline evaluation. Patients who have received a depot antipsychotic within one treatment cycle prior to screening. Patients who have taken an antidepressant, or lithium within 4 weeks of the trial, 6 weeks for fluoxetine. Patients who have taken any psychotropic medication within 1 week of the trial. Patients who require concomitant medications during the trial.
11. Patients with a suspected history of hypersensitivity or intolerance to risperidone.
12. Patients with a known or suspected history of severe drug allergy or hypersensitivity (e.g., Steven Johnson's syndrome)

13. Patients with an anticipated life expectancy of six months or less.

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