Background: Patients with intellectual disabilities have reduced ability to cope with stress and often respond to adversity with inappropriately aggressive or challenging behavior. To address this disruptive behavior, anti-psychotic drugs are prescribed for up to 45 percent of persons with intellectual disabilities living in residential facilities and for 20 percent of those living in community settings. Despite the common use of these drugs, only about 15 percent of patients with intellectual disabilities are affected by psychiatric illness. There is little evidence to demonstrate the effectiveness of antipsychotic drugs for the treatment of disruptive behavior in persons who have intellectual disabilities without psychiatric illness. Tyrer and colleagues evaluated the effects of first- and second-generation antipsychotics in this setting.

The Study: This placebo-controlled clinical trial included patients receiving treatment from community services for persons with intellectual disabilities (IQ of less than 75). Participants had no history of psychosis, had not used injected antipsychotics within the preceding three weeks or oral antipsychotics within the preceding week, had at least two episodes of aggressive behavior within the preceding week, and had a modified overt aggression scale (MOAS) score of 4 or more. Each participant was screened for mental illness at baseline. Informed consent was obtained from the patient, if possible, or from a responsible caretaker.

Participants were allocated by a permuted blocks procedure to receive placebo; risperidone (Risperdal), 1.0 mg daily; or haloperidol (Haldol), 2.5 mg daily. A double-blind procedure was subsequently used. Daily doses could be increased, at the discretion of the treating physician, to up to 2.0 mg of risperidone or 5.0 mg of haloperidol. Larger doses were permitted in exceptional circumstances. Lorazepam (Ativan), up to 2.0 mg, could be used as a rescue medication, with the option of continuing the therapy for up to six months.

MOAS scores were performed for the 86 eligible participants at baseline and at weeks 4, 12, and 26. Other data gathered at the same intervals included quality of life, caretaker burden, severity of illness, and adverse medication effects.

Results: The three groups were comparable in all major variables. The average age of participants was about 40 years, and about 60 percent of each group consisted of men. Fewer than 20 percent of participants had profound intellectual disability. Pill counts indicated adherence levels of 80 percent or more, and the mean doses used were 1.78 mg of risperidone and 2.94 mg of haloperidol. Seventy-one percent of participants completed follow-up at 12 weeks, and 57 percent at 26 weeks.

In all three groups, MOAS scores fell dramatically in the first week. By week 4, the greatest decrease from baseline occurred in the placebo group (79 percent), followed by the haloperidol group (65 percent) and the risperidone group (58 percent); however, these differences were not statistically significant. Similar improvements in the other measures occurred in all three groups. For those who remained in the study, improvements were sustained throughout the 26 weeks in all three groups. Only three patients withdrew from the study because of adverse medication effects (one in the haloperidol group and two in the risperidone group). The rescue medication was used for three participants (10 percent) in the placebo group, six (21 percent) in the risperidone group, and two (7 percent) in the haloperidol group.

Conclusion: The authors conclude that the greatest reduction in disruptive behavior occurred in the placebo group. The three groups did not differ in other important outcomes, such as quality of life, caretaker burden, or adverse medication effects. They do not recommend routine use of antipsychotic medications to decrease aggressive or challenging behavior in persons with intellectual disabilities. It may be best to limit these drugs to severe or emergency situations or to specific subgroups of patients.