Anticholinergic drugs and the risk of dementia: a nested case control study

Dementia is a common and devastating condition in older people, with serious consequences for affected individuals and their families and carers as well as the wider society. It is estimated that dementia affects 1 in every 14 people aged 65 years and over, and that there are around 850,000 people living with dementia in the UK. This is expected to increase as the population ages.

There are several known risk factors for dementia such as older age, obesity, smoking, alcohol and other illnesses such as diabetes, depression and stroke. There is also some research which shows that certain medicines that are prescribed to older people for a range of conditions might increase their risk of developing dementia. These medicines are called anticholinergic drugs, and are used to treat conditions such as asthma, incontinence, dizziness, depression and insomnia. These medicines have certain known side effects, which include confusion and memory loss especially in the elderly, and might also increase the risk of dementia, especially if taken for a long time. However studies which have looked at this have generally been small, of a short duration and have not accounted for the effects of some other risk factors for dementia.

The proposed study will use a database containing anonymised medical records from general practice to select a group of people aged 65 and over who have been diagnosed with dementia. A second group of people for comparison will be identified from the same practices but who do not have dementia. Information on previous prescriptions for anticholinergic drugs over a period of many years will be used to see whether patients with dementia were more likely to have been prescribed anticholinergic drugs than the comparison group of patients without dementia. This will help to establish whether these medicines increase the risk of dementia.