Drugs increase dementia risk

Heavy use of anticholinergic drugs seems to increase the likelihood of developing Alzheimer's disease (AD), new research has shown. The study suggested 'that a person taking an anticholinergic, such as oxybutynin chloride, 5mg per day, or doxepin hydrochloride, 10mg per day, for more than three years would have a greater risk of dementia'.

Both types of anticholinergic actions can impair some aspects of cognition (memory and attention). Older people seem to be especially sensitive to anticholinergics' effects on the central nervous system (CNS). Meanwhile, AD patients show reduced levels of acetylcholine.

To investigate the link between AD and anticholinergic drugs, researchers enrolled 3434 people aged 65 years or older without dementia. Using pharmacy data, they ascertained cumulative exposure to anticholinergics, expressed as total standardised daily doses (TSDDs) dispensed in the past 10 years. They excluded the most recent 12 months to avoid confounding from treatment of AD's prodromal symptoms but updated cumulative exposure during follow up.