Can Medication Affect Memory?

Many over-the-counter and prescription drugs have side effects that can scramble thinking and dim memory. Older people tend to be more sensitive to these effects. Moreover, older people often take multiple medications. Although one drug alone may not cause problems, the cumulative effect of several drugs may make it difficult to carry out basic daily activities such as bathing, dressing, and even walking.

Popular over-the-counter drugs with these side effects — often listed on the label as dry mouth, blurred vision, and confused thinking — include antihistamines used to treat allergies, colds, and coughs. There are literally dozens of these products lining drugstore shelves; check the ingredient list for brompheniramine, chlorpheniramine, and diphenhydramine, all of which have these side effects. Doctors sometimes recommend that people take diphenhydramine (better known by its trade name, Benadryl) to help them fall asleep. In fact, diphenhydramine is also the main ingredient in many over-the-counter sleep aids, such as Compoz, Sominex, and Unisom, as well as Tylenol PM.

Among prescription drugs, the prime culprits include certain ones used to treat depression, such as amitriptyline (Elavil) and nortriptyline (Aventyl, Pamelor); overactive bladder, such as oxybutynin (Ditropan, Urotrol, and other brands); and heartburn, such as cimetidine (Tagamet).

These medications share a common mechanism: blocking the neurotransmitter acetylcholine, which is why they are known as anticholinergic drugs. Certain drugs used to treat Alzheimer’s disease, such as donepezil (Aricept), have the exact opposite effect — they boost levels of acetylcholine in the brain. So it makes sense to steer clear of anticholinergics when possible. One study reported that the use of medications with anticholinergic activity was linked to a more rapid decline in the cognitive performance of older adults who had been studied an average of 7.8 years.

If you’ve noticed any kind of confusion or thinking problems since starting a new medication, ask your doctor about a possible substitute, which is often (but not always) possible. For some potential alternatives to drugs with anticholinergic actions, see Table 2.



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