Assessing the Utility of Atypical Antipsychotic Medication in Adults With Mild Mental Retardation and Comorbid Psychiatric Disorders

Objective: Research on psychiatric outcomes among individuals dually diagnosed with mild mental retardation and co-occurring mental illness who are treated with antipsychotic medication is markedly limited due to difficulties encountered in (1) making valid and reliable psychiatric diagnoses and (2) accurately rating and following psychiatric symptom change over time in this specialty population.

Method: To address these issues, DSM-IV psychiatric diagnoses were made by an experienced dual-diagnosis clinician, and the Aberrant Behavior Checklist (ABC) and the Global Assessment of Functioning were used to assess behavioral and psychiatric features in a psychiatric partial hospital setting. Data were collected by chart review from 72 patients admitted consecutively from January 1998 to December 1999. Assessments were compared at admission and discharge in this retrospective study for 3 treatment groups that were defined by antipsychotic medication status at discharge: no antipsychotic (N = 15), atypical antipsychotic only (N = 41), and mixed atypical/typical antipsychotics or typical antipsychotic only (N = 16).

Results: Improvement on the ABC social withdrawal subscale was greater for atypical antipsychotic medication-treated, dually diagnosed patients than for those who received other treatment regimens. In addition, a dose-response relationship was observed for this subscale and atypical antipsychotic medication dose.

Conclusion: For certain psychotic patients with mild mental retardation, the atypical antipsychotics may be an appropriate and effective treatment modality.