BEHAVIOURLearning disability refers to individuals whose IQ is measured at less than 70. Overall the prevalence of learning disability in the UK is between 1 and 2% of the population, 1 85% will have mild learning disability. Challenging behaviour is very common in this group, with about 20% of children and 15% of adults exhibiting it.2 3 The lower the IQ greater the prevalence of challenging behaviour, approaching 40% 4 in those with severe learning disability. Emerson 5 defined challenging behaviour as:"Culturally abnormal behaviour(s) of such intensity, frequency or duration that the physical safety of the person or others is likely to be placed in serious jeopardy, or behaviour which is likely to seriously limit use of, or result in the person being denied access to ordinary community facilities".Behaviour disturbance in individuals with learning disability stems from an interplay of two types of factor: environmentally independent factors, such as stage of development, preservation of homeostasis, habitual state of arousal of the individual, organic or functional mental illness, and environmentally dependent factors, such as aberrant behaviours that have been inadvertently reinforced, and aberrant, failed communication attempts. 5 Behaviour disturbances can further be caused by major emotional universal needs in learning disabled people (for example security, friendship) being unmet.The challenging behaviours exhibited include aggression, destructiveness, self injury and stereotypy. These can cause distress or harm to the individual, to their carers or to the general public.
CLINICAL MANAGEMENTManaging individuals with challenging behaviour remains a very diYcult task. A number of options are available. The most widely adopted is the use of psychotropic drugs, of which antipsychotic drugs are most frequently used. Other options are based upon behaviour modification techniques. These are usually carried out by specialised professionals, involve assessment of the behaviour, looking specifically at triggering factors and the impact of the behaviour on the environment, and then developing strategies to modify it. Antipsychotic drugs are by the far the easiest option to use in terms of cost, time and administration.In learning disability there is a high use of antipsychotic drugs. About 22-45% of individuals residing in hospitals and 20% in the community will be taking antipsychotic drugs. 6 The prevalence of psychiatric illness is between 8-15% 7 which means that 7-30% of all individuals taking antipsychotic drugs in institutions and 5-12% in the community setting, are doing so in order to manage their challenging behaviour alone. Between 9-26% of individuals taking antipsychotic drugs will be on more than one type of antipsychotic drug. The three commonest antipsychotic drugs used are thioridazine, chlorpromazine and haloperidol.Not all individuals with challenging behaviour are prescribed antipsychotic drugs.