Prescribing antipsychotic drugs such as risperidone (Risperdal, Johnson & Johnson) to curb aggressive behaviour in people with learning disabilities may be less effective than a placebo, a new study suggests.

While the use of antipsychotics to treat aggressive outbursts in people with intellectual disability has become standard medical practice, evidence for the drugs’ effectiveness in this setting is equivocal while concerns have been raised about over-medication, particularly in view of the potential for long-term side-effects such as dystonias (involuntary muscle contractions), parkinsonism (rigidity and tremors), weight gain, tachycardia, hypotension and impotence.

In the UK, some 200,000 people with intellectual disability who show challenging aggressive behaviour are given antipsychotics. In the study published in the latest issue of The Lancet (2008; 371:57-63), researchers led by Professor Peter Tyrer from the Department of Psychological Medicine at Imperial College, London tested the validity of this strategy by measuring the effects of antipsychotics and placebos on the aggressive behaviour of 86 non-psychotic patients in 10 centres in England and Wales and one in Queensland, Australia.

The patients were randomised to risperidone (n = 29), the first-generation antipsychotic haloperidol (Haldol, also Johnson & Johnson; n = 28) or placebo (n = 29). Clinical assessments of aggression, aberrant behaviour, quality of life and adverse drug effects as well as carer uplift (i.e., positive feelings about care of the disabled person) and burden, together with overall costs, were recorded at weeks four, 12 and 26 of the trial. The primary outcome was change in aggression after four weeks’ treatment, as measured with the modified overt aggression scale (MOAS).

Reduced agression
At the four-week stage, aggression had reduced substantially with all three treatments but the biggest change was seen in the placebo group, with a median decrease of nine or 79% from baseline in the MOAS score. The reductions in the MOAS score for risperidone and haloperidol after four weeks were seven/58% from baseline and 6.5/65% respectively.

Although there were no significant differences between treatments in other respects (including adverse effects), at no point in the trial did the patients given placebo show any evidence of a worse response than those assigned to either of the antipsychotics, the authors noted. One explanation for the marked response seen with placebo could be that people with learning disabilities often feel neglected and hence benefited to an unusual degree from the attention given to them in the study.

“Our trial shows that aggressive challenging behaviour in people with intellectual ability decreases whether or not active medication is given,” the researchers concluded. “The routine prescription of antipsychotic drugs early in the management of aggressive challenging behaviour, even in low doses, should no longer be regarded as a satisfactory form of care.” Nonetheless, they added, the results “should not be interpreted as an indication that antipsychotic drugs have no place in some aspects of behaviour disturbance”.

Johnson & Johnson has not commented on the study, other than to say that it only promotes the antipsychotics for approved uses.