You may already know that the anticholinergic drugs you prescribe your elderly patients for their
incontinence, heartburn or insomnia can have a detrimental effect on their cognition. Now, a pair
of new studies shows these same meds also affect seniors' day-to-day physical functioning.
Both studies were led by Wake Forest University geriatrician Kaycee Sink. The first, in the May
issue of the Journal of the American Geriatrics Society, measured the ability to perform activities
of daily living (ADL) in demented patients taking both an anticholinergic incontinence drug and
a cholinesterase inhibitor (ChI) for dementia. The researchers followed these patients for two
years and compared their scores with those of demented seniors who were only on a ChI.
"We saw no effect in patients who were already severely demented and functionally impaired,"
Dr Sink told NRM. "But the highest functioning nursing home residents declined an average of
two points more per year than residents who were taking only the ChI. A two-point decline is
pretty significant and would translate to someone moving from being quite independent in an
ADL, like dressing or eating, to needing extensive help."
The problem is that ChIs counter cognitive and functional decline in demented patients by
boosting the neurotransmitter acetylcholine, while anticholinergics actually decrease
acetylcholine by acting on muscarinic receptors. In other words, the two drugs appear to cancel
each other out.
"In general, we should be avoiding anticholinergics in demented patients because they already
have a cholinergic deficit," says Dr Sink. "And when used with ChI, we're likely spending money
for less benefit." She suspects the ChIs are probably affecting the efficacy of the incontinence
meds as well. It's thought that about 30% of dementia patients are on both kinds of drugs.
MILD & MIGHTY
In early May, Dr Sink presented another study at the American Geriatrics Society meeting in
Washington, DC, that tackled the question of whether milder anticholinergics, taken alone or
with others, impaired seniors' physical function. "Some are well-known to have these properties,
but many are not typically thought of as being anticholinergic, such as furosemide," says Dr Sink.
"We found that if they're on one mild anticholinergic, there's not much of an effect on function.
But with more than one, there was a clinically significant effect." That effect was the equivalent
to the patient aging three or four years. "We were looking at people who were already 75 years or
older, so if they were taking these drugs it would age them to being 78 or 79 years old
functionally."
The evidence against anticholinergic use in the elderly seems compelling, so why do doctors
continue to prescribe them? "I don't know," admits Dr Sink. "I see a lot of elderly patients on
strongly anticholinergic drugs. Geriatricians are well-aware that elderly patients shouldn't be
given these drugs, but I don't know about other physicians." Around 60% of nursing home
patients and 23% of community dwelling seniors are thought to be on some type of
anticholinergic medication.
But Dr Sink hastens to add that prescribing isn't a perfect science, and research into
anticholinergic risks is still relatively new. "When you're prescribing, everything's a risk-benefit
ratio," she says. "We have still not shown in a convincing way that the risk outweighs the benefit.
But we should be choosing the drug that has the fewest risks."
|
