Might taking multiple medicines with similar properties be bad for your health? Recent research on medicines with anticholinergic properties showed that taking multiple medicines cumulatively increased the risk of death and decline in brain function.
Other studies producing similar findings have appeared in the BMJ, the Archives of General Psychiatry and the American Journal of Psychiatry.
What are Anticholinergic medicines? - Many commonly used drugs fall into this category, including antihistamines, antispasmodics, skeletal muscle relaxants, antipsychotics and tricyclic antidepressants. As anticholinergic drugs they are used to help reduce and block the effects of acetylcholine (a neurotransmitter; which helps in sending messages between different parts of the body). Prescription and over-the-counter drugs taken for allergies, muscle aches and pains, stomach-related problems and psychological wellbeing usually display varying levels of anticholinergic activity.
What did the actual study involve? - This was a retrospective longitudinal study of participants enrolled in the Medical Research Council Cognitive Function and Ageing Study, between 1991 and 1993, undertaken by researchers from the University of East Anglia, University of Cambridge, University College London and a number of other reputed research institutions in the UK and US.
The aim of the study was to determine whether using medications with possible and definite anticholinergic activity increased the risk of cognitive impairment and mortality in older people, and whether this risk was cumulative in nature. Data from over 13,000 community and institutionalised individuals (aged 65 and over) was used in the study.
At the start of the study, 47% of the sample used medication with possible anticholinergic effects and 4% used medication with definite anticholinergic effects. After taking into consideration (and statistically adjusting for) age, sex, education, social class, number of medications, number of comorbid health conditions and initial cognitive performance, individuals using medication with definite anticholinergic effects had a greater decline in cognitive function than those not taking any anticholinergic medicines. The use of possible anticholinergic medications was not associated with decline in cognitive functioning. On the other hand, mortality at the end of two years was greater for both those taking definite and possible anticholinergics.
How reliable is the study? - This study has many strengths. These include the robustness of the measures used for cognitive functioning, a large and nationally representative sample, a 96% retention rate of study participants over two years, and controlling for many baseline characteristics during analyses.
However, the limitations of the study also need to be considered. Firstly, the data is from nearly 20 years ago when medical practices and drugs were different. A more recent and modern study is likely to be required to explore and confirm the findings. Also, there was no way of confirming that participants continued their medication regularly over the two year period. They could have omitted certain drugs for short periods or reduced dosage etc. Lastly, the study did not take into consideration subclinical conditions (diseases that have been initiated into the body but hadn’t yet manifested symptoms); hence, it is possible that conditions such as dementia or other cognitive degeneration had already set in.
What does this mean? - DrClare Gerada, chairman of the Royal College of GPs, said, "The first thing is not to worry too much, the second thing is to discuss it with your doctor or the pharmacist, and the third thing is do not stop your medicines without taking advice first."
The findings highlight the significance of doctors ensuring carefully calculated drug prescription. As an individual, you can regularly review your medication with your doctor so that unnecessary medicines can be stopped. Also, take his/her advice on over-the-counter medications and whether they are necessary or not in various instances. Most medicines (anticholinergic or not!) have some minimal side effects; hence, it is not so surprising that anticholinergic medications have specific side effects too. If the condition that’s being treated is a far greater risk to your health, then it makes more sense to take the medication until advised otherwise by your doctor
Published 23/09/2011, Review date May 2015