February 13, 2006
Various commonly prescribed prescription medicines may impair thinking and memory in elderly men and women. Many of the seniors taking these drugs were given a diagnosis of "mild cognitive impairment," a condition that may occur before the development of Alzheimer's disease. Despite this diagnosis, the seniors taking these medications were not at increased risk of developing Alzheimer's down the road. In addition, a senior's cognitive impairment could probably be reversed if the medicine was the cause and could be discontinued.
However, such drugs might be necessary for the health of a given patient. The findings, published in the British Medical Journal, underscore the importance of considering medication side effects as a possible cause of memory loss in seniors.
The medicines that caused cognitive loss in the study are known as "anti-cholinergic" drugs because they block the action of a brain chemical called "acetylcholine." They are commonly prescribed to treat a wide range of ailments common in the elderly, including depression, high blood pressure, heart disease, and bladder spasms. Among the drugs considered in the study were the anxiety fighter Xanax (alprazolam), the antidepressants Asendin (amoxapine) and Elavil (amitriptyline), the high blood pressure medicine Lasix (furosemide), the heart medicine Lanoxin (digoxin), the asthma reliever theophylline, and the Parkinson's disease drug Norflex (orphenadrine).
For the study, French researchers enlisted 372 seniors, many of whom were in their seventies and eighties. More than half were taking an anti-cholinergic drug over an extended period (at least a year), and almost one in 10 were taking several. None of the seniors had Alzheimer's disease at the start of the study, though more than a third were diagnosed with mild cognitive impairment.
The study participants were given regular physical and memory exams. After a year, the researchers found that 80 percent of the seniors who had been taking anti-cholinergic drugs long-term were considered to have mild cognitive impairment. In contrast, only 35 percent of elderly who were not taking these medications were diagnosed with the condition. After eight years, however, those medication users who were diagnosed with mild cognitive impairment were no more likely to develop Alzheimer's disease than those who were not receiving these drugs.
"Elderly people taking anti-cholinergic drugs had significant deficits in cognitive functioning and were highly likely to be classified as mildly cognitively impaired," the authors conclude. "However, they were not at increased risk for dementia. Doctors should assess current use of anti-cholinergic drugs in elderly people with mild cognitive impairment" before they make a diagnosis of mild cognitive impairment or Alzheimer's disease.
It might be possible to reduce a patient's use of anti-cholinergic drugs, especially in cases where a patient might have been over-medicated. Then, a drug to treat dementia, like Aricept, might not be necessary.
Check Prescription Medications
The findings are consistent with earlier studies showing that anti-cholinergic drugs can produce cognitive problems even in otherwise mentally intact young adults. Elderly people are especially likely to be prescribed these drugs because of various diseases of old age and, the study shows, experience memory problems.
In the current study, taking anti-cholinergic drugs produced memory and thinking deficits similar to those that occur in young people. Four out of five of those taking the drugs long-term did poorly on memory tests. The medications did not affect all aspects of memory and thinking equally. Compared with seniors of similar age who were not taking these drugs, elderly on anti-cholinergic medicines had slower reaction times, did poorly on visual and spatial memory tests (such as the ability to redraw a shape projected on a computer screen), and had poorer narrative recall (such as the ability to retell a story they've just heard). However, the medications did not seem to affect other aspects of memory or reasoning, including the ability to recall lists of words or proper names.
Despite some problems with memory, seniors taking these medications were not at increased risk of developing dementia years down the road. The findings underscore that doctors (and patients) should consider these drugs as one possible cause of mental deficits in the elderly.
The study authors also suggest that treatment with Alzheimer's drugs may be inappropriate for those who suffer from intellectual deficits because of the medications. Before prescribing Alzheimer's drugs to elderly patients with mild impairments, doctors should check to see if patients are already taking any drugs in this class, the investigators advise. Based on these findings, anti-cholinergic drugs should also be considered as a possible cause of mild mental impairment that can be reversed, the authors add.
Seniors who are taking these drugs should not stop taking them or reduce the dose on their own, because they may be necessary for the patient's health. However, patients should discuss side effects with their doctors. For more on mild cognitive impairment, the treatment of Alzheimer's disease, and the Fisher Center for Alzheimer's Research Foundation's search for a cure, visit www.ALZinfo.org.
By www.ALZinfo.org, The Alzheimer's Information Site.
Marie L Ancelin, Sylvaine Artero, Florence Portet, et al: "Non-degenerative mild cognitive impairment in elderly people and use of anticholinergic drugs: longitudinal cohort study. British Medical Journal, doi:10.1136/bmj.38740.439664.DE, published online, February 1, 2006.