Psychiatric disorders are common in the elderly. Antidepressants are probably underprescribed. In recurrent depression, lifelong prophylaxis may be required. Benzodiazepines can aggravate cognitive impairment and cause falls; they should not be used for chronic insomnia. Antipsychotic drugs are useful for the treatment of delusions and hallucinations but are less effective for disturbed behaviour in dementia sufferers. There are no satisfactory drugs for treating dementia at present, but promising palliative treatments for Alzheimer's disease are under trial.