11: disorders of memory and intellect.

The clinical approach to the patient with a suspected disorder of memory and intellect is to establish whether it is dementia, which parts of the brain are affected, what is the cause, what is the prognosis, and what can be done about it. The diagnosis of dementia usually requires the involvement of memory and at least one other cognitive system. Delirium and depression are important differential diagnoses. Patients with dementia should usually have some simple investigations after a careful history-taking and examination to identify "reversible" causes. The commonest cause of dementia is Alzheimer's disease, in which short-term memory disturbance is usually prominent. Other causes of dementia include cerebrovascular disease, Lewy-body disease and Pick's disease. There is now hope for patients with Alzheimer's disease (which can be treated with some success with cholinesterase inhibitors) and patients with vascular dementia, in whom aggressive control of causal risk factors may retard progression.