Factors associated with a good response to lithium in aggressive mentally handicapped subjects.

Twenty-five (25) mentally handicapped in-patient adults with persistent aggressive behaviour took part in a double-blind crossover trial lasting 5 months comparing the effects of lithium with placebo on aspects of aggressive behaviour. All patients were receiving neuroleptic and/or anticonvulsant drugs which were continued during the trial. Seventeen (17) of the patients showed greater improvement during the lithium phase compared to placebo. Multiple regression analysis was carried out to determine which of 17 background variables were related to outcome. The following factors were associated with a good response to lithium: less than one aggressive episode per week before starting treatment, overactivity, stereotypic behaviour, female sex and epilepsy. No patient became toxic during the investigation although lithium levels were maintained within the therapeutic range (0.5-0.8 mmol/l).