A recent study from the University of Eastern Finland shows that among users of antidementia drugs, persons using memantine have the highest risk of pneumonia. The use of rivastigmine patches is associated with an increased risk as well. The study found that persons using donepezil or galantamine had the lowest risk of pneumonia. However, persons using memantine or rivastigmine patches had a 1.6 and 1.15 times higher risk of pneumonia, respectively, but no elevated risk was observed among patients using rivastigmine in capsule form. The real risk increase may be even higher, as only cases of pneumonia leading to hospitalisation or death were taken into account.

The study is the first to compare the risk of pneumonia associated with different antidementia drugs and drug forms. The results are not likely to be explained by differences between drug molecules, as rivastigmine was associated with an increased risk of pneumonia in patch form only. The increased pneumonia risk among persons using memantine or rivastigmine patches may be explained at least partly by the fact that these medications are often used in more advanced states of dementia. However, all participants were home-dwelling persons.

The study is based on data from a nationwide register-based study (MEDALZ) conducted at the University of Eastern Finland. The risk of pneumonia was compared among users of different antidementia drugs. The study population consisted of 65,481 persons diagnosed with Alzheimer's disease during 2005-2011 in Finland.

No cure for Alzheimer's diseases currently exists, but the progression of the disease can be slowed down by antidementia drugs, such as memantine and acetylcholinesterase inhibitors such as donepezil, galantamine, and rivastigmine. Persons with Alzheimer's disease have an elevated risk of pneumonia, and it is one of the most common causes of hospitalisation among persons with Alzheimer's disease. Pneumonia is also a common cause of death in this population.

The findings published in the Annals of Medicine. In addition to researchers from the University of Eastern Finland, also researchers from the University of Turku and Karolinska Institutet participated in the study.

Lampela P, Tolppanen AM, Tanskanen A, Tiihonen J, Lavikainen P, Hartikainen S, Taipale H.
Use of antidementia drugs and risk of pneumonia in older persons with Alzheimer's disease.
Annals of Medicine, published online October 27, 2016, doi: 10.1080/07853890.2016.1254349