Clozapine Treatment in a Population of Adults With Mental Retardation

Background: There is a paucity of data on
the use of clozapine in patients with mental retardation and
comorbid psychiatric illness. The authors describe their recent
clinical experience using clozapine in treatment-refractory
patients with mental retardation and severe psychiatric illness.

Method: A retrospective review was performed on
the records of all patients admitted to a university-affiliated,
specialized inpatient psychiatry service who were selected for
clozapine therapy from March 1994 through December 1997 (N = 33).
Patients had DSM-IV diagnoses of schizophrenia, schizoaffective
disorder, bipolar disorder, delusional disorder, or psychotic
disorder NOS and were considered treatment resistant. All had
deficits in functioning well beyond those expected for their
degree of cognitive deficits and adaptive delays.

Results: Of 33 initial patients, 26
remained on clozapine therapy for a follow-up duration of 5 to 48
months (mean = 24.8 months). Evaluation at follow-up revealed
Clinical Global Impressions-Improvement (CGI-I) scores from 1 to
4 with a mean ± SD improvement of 2.0 ± 0.8 (much improved).
The mean ± SD rating of the CGI-Efficacy Index was 5 ±
2.6 (decided improvement and partial remission of symptoms with
no interference from side effects). The 6 patients who were not
maintained on clozapine therapy over the study period did
not significantly differ from the clozapine group in gender,
race, age, side effects, or diagnosis. One patient was lost to
follow-up. Side effects were mild and transient with constipation
being the most common (N = 10). There were no significant
cardiovascular side effects and no seizures. No patients
discontinued treatment due to agranulocytosis.

Conclusion: The current investigation
lends support to the conclusion that clozapine appears to be
safe, efficacious, and well tolerated in individuals with mental
retardation and comorbid psychiatric illness.