Dementia in old age.

1. About 10% of patients aged 75 and over are demented to an appreciable degree; the proportion may exceed 20% in those over 85. 2. Potentially reversible causes include pernicious anaemia, hypothyroidism, frontal meningioma, and normal pressure hydrocephalus. In many cases, however, treatment has little effect on cognitive function. 3. Around 50% are due to Alzheimer's disease, 20% to multi-infarct dementia, and a further 15-20% have both conditions. 4. Recognition is facilitated by using a standard test of cognitive function (the Abbreviated Mental Test Score or the Mini Mental State Examination). 5. Dementia must be distinguished from delirium and depression. 6. Investigations by the general practitioner include full blood count and TSH. Urine should be tested, particularly if there is incontinence. Physical examination should exclude intercurrent disease and check for neurological deficits. 7. Sudden onset of confusion without obviously remediable cause and the need for respite care are indications for referral. Patients may also be referred for initial assessment. 8. An individually tailored care package should be designed for each patient. It should be clear who is taking responsibility for follow-up and monitoring. 9. Carers should be supported, encouraged to ventilate their feelings, put in contact with appropriate voluntary groups, advised on appropriate allowances, and offered respite care when needed.