The objective of a UK-based case-controlled study recently published in the British Medical Journal was to estimate the association between the duration and level of exposure to different classes of anticholinergic drugs and subsequent incidence of dementia.
The nine-year long study included over 40,000 patients aged 65-99 with a diagnosis of dementia and a control group of over 280,000 patients without dementia.
During the drug exposure period, 35 percent of dementia patients and 30 percent of controls were prescribed at least one anticholinergic drug with an Anticholinergic Cognitive Burden (ACB) score of 3. The five most common drugs were amitriptyline (29%), dosulepin (16%), paroxetine (8%), oxybutynin (7%), and tolterodine (7%).
There was a significant association between dementia incidence and any prescription of antidepressant, anti-Parkinson or urological drugs
Only 1,429 (3.5%) cases and 7,909 (2.8%) controls were prescribed drugs with an ACB score of 2, with carbamazepine accounting for 87 percent of these prescriptions. Most patients received at least one prescription for a drug with an ACB score of 1 during the drug exposure period, with cardiovascular drugs accounting for 63 percent of these prescriptions.
There was a significant association between dementia incidence and any prescription of antidepressant, anti-Parkinson or urological drugs with an ACB score of 3, but no association with antispasmodic, antipsychotic, antihistamine or other drugs with an ACB score of 3. Prescriptions for drugs with an ACB score of 2 were relatively rare, and so results were imprecise in this group, but there is some evidence for an association between dementia incidence and prescription of anti-Parkinson drugs. Positive associations were found for antidepressant drugs with an ACB score of 1 with an
increased risk of dementia, but not with any other drugs with an ACB score of 1. Use of gastrointestinal drugs with an ACB score of 1 or 3, and cardiovascular drugs with an ACB score of 1 was associated with a minor reduction in the risk of dementia.
With regards to the duration of increased risk, antidepressant, urological and anti-Parkinson drugs with an ACB score of 3 were linked to future dementia incidence (odds ratio of 1.17, 95% confidence interval, 1.10 to 1.24), with associations persisting up to 20 years after exposure. Gastrointestinal and cardiovascular drugs were not associated with later dementia incidence.
Read the paper here:
Richardson K et al. Anticholinergic drugs and risk of dementia: case-control study. BMJ2018;361:k1315