Older nursing home residents who took medications for dementia and incontinence at the same time had a 50 percent faster decline in function than those who were being treated only for dementia, according to a study from researchers at Wake Forest University School of Medicine and colleagues.
"It is likely that the oppositional effects of the drugs contributed to the accelerated decline," said Kaycee M. Sink, M.D., M.A.S., lead author. "Over a year's time, the decline we observed would represent a resident going from requiring only limited assistance in an activity to being completely dependent, or from requiring only supervision to requiring extensive assistance in an activity."
The combination of drugs affected older adults who started out with higher levels of function in activities of daily living such as dressing, personal hygiene, toileting, transferring, bed mobility, eating and being able to get around the unit. The results were published online by the Journal of the American Geriatrics Society and will appear in a future print issue.
The two most common medical conditions among nursing home residents are dementia and urinary incontinence and they often coexist. The study involved 395 nursing home residents in Indiana who were taking medications for both conditions and 3,141 who were taking only a dementia medication.
Residents included in the analysis were age 65 and older and had had at least two consecutive prescriptions for cholinesterase inhibitors, a family of drugs used to treat dementia. Examples include donepezil (Aricept®), galantamine (Razadyne®), rivastigmine (Exelon®), and tacrine (Cognex®). These drugs are designed to increase levels of acetylcholine, a chemical that enhances communication between nerve cells in the brain.
About 10 percent of the residents were also taking either oxybutynin or tolterodine, the two most commonly prescribed drugs for urinary incontinence. These drugs are known as anticholinergic agents and are designed to block acetylcholine.
"The two drugs are pharmacological opposites, which led us to hypothesize that the simultaneous treatment of dementia and incontinence could lead to reduced effectiveness of one or both drugs," said Sink, an assistant professor of internal medicine-gerontology.
She said the finding of the more rapid decline among residents taking both types of drugs represents a significant public health problem because an estimated 33 percent of people with dementia also take a drug for incontinence.
"Until now, the clinical dilemma for managing incontinence and dementia has been largely theoretical. This research suggests it may lead to worse outcomes, which is the opposite intention of therapy for dementia."
The researchers also measured whether the residents taking both drugs also experienced a decline in mental function, but there was no difference between the two groups, possibly because the test was not sensitive enough. Sink said that similar research should be extended to community-dwelling older adults with dementia and that more sensitive measures for cognition should be used. Previous studies have shown that the bladder medications are associated with cognitive decline and that people with dementia are especially sensitive to this side effect.
"The results suggest that clinicians should continue to try non-drug management strategies for incontinence before beginning therapy with one of these common drugs," said Sink.
She noted that the study was conducted in 2003 and 2004, before newer incontinence medications were introduced that may have less effect on acetylcholine in the brain.