This chapter describes the psychiatric disorders of old age such as dementia, delirium, neurosis and suicide. It discusses the epidemiology, aetiology, course and outcome, and the management and treatment of various psychiatric disorders of old age. The needs of older people with mental health problems are not confined simply to mental health but also physical health and social care needs. Alzheimer's disease (AD) has been reported as consistently more common than vascular dementia in studies in developed countries. Genetic abnormalities have been shown to be risk factors for dementia. A medical history should be taken with particular relevance to risk factors for cardiovascular or cerebrovascular disease and a history of transient ischaemic attacks. The clinical management of a person with dementia is considered under three main headings: general care and support; treatment of cognitive symptoms; and management of behavioural and psychological symptoms.