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

Karen J. Shedlack, M.D.; John Hennen, Ph.D.;Christine Magee, M.S.; and Daniel M. Cheron, B.A.

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.

(J Clin Psychiatry 2005;66:52-62)

Received May 9, 2004; accepted June 23, 2004. From the Developmental Disabilities Program, McLean Hospital, Belmont (all authors); Harvard Medical School, Boston (Drs. Shedlack and Hennen); May Behavioral Health, Norwood (Ms. Magee); and Boston College, Chestnut Hill (Mr. Cheron), Mass.

This study was funded in part by a gift from the Manzi Foundation, Boston, Mass.

Presented in part at the annual meeting of the National Association for the Dually Diagnosed, New Orleans, La., October 2001, and the 155th annual meeting of the American Psychiatric Association, Philadelphia, Pa., May 2002.

The authors thank Anne Doherty, M.F.A.; Mary Jo Iacoboni, B.S.N., R.N.; Robert Sisson, Ph.D.; and the Manzi Foundation (Boston, Mass.) for their efforts and support of this project.

Corresponding author and reprints: Karen J. Shedlack, M.D., Developmental Disabilities Program, McLean Hospital, 115 Mill St., Belmont, MA 02478 (e-mail: k.shedlack@comcast.net).