Behavioural disorders in demented elderly patients. Current issues in pharmacotherapy

Abstract

Dementias are a significant cause of morbidity and mortality in developed countries. Although the key diagnostic factor that defines the dementias is a sustained loss of cognitive ability, dementias are also frequently accompanied by debilitating behavioural disturbances. These behavioural disturbances cause significant problems for the caregivers of people with dementia and are major factors precipitating institutionalisation. The pathophysiological relationship between cognitive and behavioural disturbances has not been well studied. In Alzheimer's disease, the major cause of dementia, behavioural problems can occur during all stages of cognitive impairment, from mild to severe. In vascular dementia, the second largest cause of dementia, behavioural problems are less predictable due to the variable course of this disease. Following a differential diagnosis of the causes of behavioural disorders, nonpharmacological and pharmacological interventions may be required. Low dosages of antipsychotics remain the mainstay for treatment of these disturbances. Although there are no known differences in efficacy among the typical antipsychotics, careful consideration of the adverse effects of these drugs must be made on a case-per-case basis. The atypical antipsychotics clozapine and risperidone are currently being studied for this indication. Non-antipsychotic medications such as β-blockers, lithium, benzodiazepines, antidepressants, anticonvulsants, buspirone and hormonal therapy have also been tried, with mixed results. Of these, the selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor antidepressants are the most promising treatments. The cognitive enhancer tacrine may be effective for the management of some behavioural disturbances, but this is still being evaluated. Nonpharmacological interventions are often recommended prior to starting a medication. Behavioural management techniques are based on the systematic review and manipulation of antecedents and/or consequences of the target behaviour. A number of algorithms have been proposed for the management of behavioural disturbances, but, as yet, there are no evidence-based approaches available. However, current research is concentrating on the phenomenology and subtypes of behavioural disturbances.