Scientists have discovered that taking a sugar pill is more effective than routine medications in treating aggression in people with intellectual disabilities.
Until now, patients with intellectual disabilities have been prescribed antipsychotic drugs — normally given to people with a psychiatric disease like schizophrenia — to treat aggressive behaviour such as head banging. But evidence for the drugs' effectiveness has been thin.
“Antipsychotic drugs are widely used because they are cheap and at high doses they sedate people,” says Eric Emerson at Lancaster University, an expert in the behaviour of intellectually disabled people.
Peter Tyrer, based at Imperial College London, led an international research project looking at 86 people with intellectual disability at clinics across England, Wales and at one centre in Australia. Patients being treated for aggressive behaviour randomly received one of two antipsychotic drugs — respiridone or haloperidol — or a placebo.
These antipsychotics have been used for more than 40 years to treat aggression in people with intellectual disabilities. They block dopamine D2 receptors, which means that people who take them have less dopamine in the limbic pathway, depriving the part of the brain linked to addiction, reward and fear. Dopamine is a key neurotransmitter of arousal.
“The drugs dampen down all behaviours, not just aggression,” says John Taylor, president elect of the British Association for Behavioural and Cognitive Psychotherapies, “with no evidence that they specifically target aggression.” They have many other effects too. “Respiridone and haloperidol are dirty drugs,” says Tyrer, “with lots of side effects like drooling, shaking, seizures, dry mouth, weight gain, skin rashes and so on.”
The drugs don't work
A careworker who did not know which medication the patients had taken assessed their behaviour against a standard measure of aggression at 4 weeks, 12 weeks, and 26 weeks. Aggression decreased substantially at 4 weeks with all three treatments, with the placebo actually coming out top with a 79% success rate, compared to 58% for respiridone and 65% for haloperidol. At later stages all three treatments had similar effects, they report in the Lancet 1.
The results raise concern over the use of antipsychotic drugs in the treatment of aggressive behaviour. People of average intelligence who get aggressive, such as people who suffer extreme road rage or are violent towards their loved ones, receive psychological intervention for their aggression instead of medication. This kind of intervention is more expensive.
Not everyone is convinced the results will stand the test of time. Christopher McDougle, a psychopharmacologist based at the Indiana University School of Medicine, notes that the doses used in the study were very small. The researchers used the doses recommended for initial treatment, but these, McDougle says, are too small to be truly therapeutic for most. He also wants to see longer follow-up periods for the study.
In the meantime, McDougle has concerns over tightly controlling antipsychotic medications in this group of people. “Good luck trying to treat these people without respiridone or haloperidol,” he says.
Tyrer is now chairing a group for the UK's National Institute of Clinical Excellence, with the aim of drawing up guidelines for treating aggressive behaviour in people with intellectual disability.
His team’s next step will be develop non-pharmacological therapies, which will involve changing the sufferer’s environment to avoid aggression triggers. “This kind of treatment is helpful with antisocial patients,” says Tyrer, “and we think it will be helpful in this group too.”
- et al. , Lancet, 371, 57-63 (2008)