Common antidepressants ‘linked to increased risk of dementia’

Anticholinergic drug use is associated with an increased risk of dementia, according to new research published in the BMJ.

The drugs, which are regularly prescribed as antidepressants and to treat incontinence, increase dementia risk even when taken 20 years before diagnosis of cognitive impairment.

Researchers analysed more than 27 million prescriptions as recorded in the medical records of 40,770 patients over age 65 diagnosed with dementia compared to the records of 283,933 older adults without dementia.

They found greater incidence of dementia among patients prescribed anticholinergic antidepressants, anticholinergic bladder medications and anticholinergic Parkinson’s disease medications than among older adults who were not prescribed these drugs. Dementia increased with greater exposure to anticholinergic medications.

Noll Campbell, PharmD, a co-author of the new study, said: ‘Anticholinergics, medications that block acetylcholine, a nervous system neurotransmitter, have previously been implicated as a potential cause of cognitive impairment. This study is large enough to evaluate the long-term effect and determine that harm may be experienced years before a diagnosis of dementia is made.’

Another co-author of the study, Malaz Boustani, said: ‘These findings make it clear that clinicians need to carefully consider the anticholinergic burden of their patients and weigh other options. Physicians should review all the anticholinergic medications – including over-the-counter drugs – that patients of all ages are taking and determine safe ways to take individuals off anticholinergic medications in the interest of preserving brain health.’

A list of medications with anticholinergic action can be found here.