For a long time doctors dismissed forgetfulness and mental confusion as a normal part of aging. But scientists now know that memory loss as you get older is by no means inevitable. Indeed, the brain can grow new brain cells and reshape their connections throughout life.
Most people are familiar with at least some of the things that can impair memory, including alcohol and drug abuse, heavy cigarette smoking, head injuries, stroke, sleep deprivation, severe stress, vitamin B12 deficiency, and illnesses such as Alzheimer's disease and depression.
But what many people don't realize is that many commonly prescribed drugs also can interfere with memory. Here are 10 of the top types of offenders.
1. Antianxiety drugs (Benzodiazepines)
Why they are prescribed: Benzodiazepines are used to treat a variety of anxiety disorders, agitation, delirium and muscle spasms, and to prevent seizures. Because benzodiazepines have a sedative effect, they are sometimes used to treat insomnia and the anxiety that can accompany depression.
Examples: Alprazolam (Xanax), chlordiazepoxide (Librium), clonazepam (Klonopin), diazepam (Valium), flurazepam (Dalmane), lorazepam (Ativan), midazolam (Versed), quazepam (Doral), temazepam (Restoril) and triazolam (Halcion).
How they can cause memory loss: Benzodiazepines dampen activity in key parts of the brain, including those involved in the transfer of events from short-term to long-term memory. Indeed, benzodiazepines are used in anesthesia for this very reason. When they're added to the anesthesiologist's cocktail of meds, patients rarely remember any unpleasantness from a procedure. Midazolam (Versed) has particularly marked amnesic properties.
Alternatives: Benzodiazepines should be prescribed only rarely in older adults, in my judgment, and then only for short periods of time. It takes older people much longer than younger people to flush these drugs out of their bodies, and the ensuing buildup puts older adults at higher risk for not just memory loss, but delirium, falls, fractures and motor vehicle accidents.
If you take one of these meds for insomnia, mild anxiety or agitation, talk with your doctor or other health care professional about treating your condition with other types of drugs or nondrug treatments. If you have insomnia, for instance, melatonin might help. Taken before bedtime in doses from 3 to 10 mg, melatonin can help to reestablish healthy sleep patterns.
Be sure to consult your health care professional before stopping or reducing the dosage of any benzodiazepine. Sudden withdrawal can trigger serious side effects, so a health professional should always monitor the process.
2. Cholesterol-lowering drugs (Statins)
Why they are prescribed: Statins are used to treat high cholesterol.
Examples: Atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), pravastatin (Pravachol), rosuvastatin (Crestor) and simvastatin (Zocor).
How they can cause memory loss: Drugs that lower blood levels of cholesterol may impair memory and other mental processes by depleting brain levels of cholesterol as well. In the brain, these lipids are vital to the formation of connections between nerve cells — the links underlying memory and learning. (The brain, in fact, contains a quarter of the body's cholesterol.)
A study published in the journal Pharmacotherapy in 2009 found that three out of four people using these drugs experienced adverse cognitive effects "probably or definitely related to" the drug. The researchers also found that 90 percent of the patients who stopped statin therapy reported improvements in cognition, sometimes within days. In February 2012, the Food and Drug Administration ordered drug companies to add a new warning label about possible memory problems to the prescribing information for statins.
Alternatives: If you're among the many older Americans without known coronary disease who are taking these drugs to treat your slightly elevated LDL ("bad") cholesterol and low HDL ("good") cholesterol), ask your doctor or other health care provider about instead taking a combination of sublingual (under-the-tongue) vitamin B12 (1,000 mcg daily), folic acid (800 mcg daily) and vitamin B6 (200 mg daily).
3. Antiseizure drugs
Why they are prescribed: Long used to treat seizures, these medications are increasingly prescribed for nerve pain, bipolar disorder, mood disorders and mania.
Examples: Acetazolamide (Diamox), carbamazepine (Tegretol), ezogabine (Potiga), gabapentin (Neurontin), lamotrigine (Lamictal), levetiracetam (Keppra), oxcarbazepine (Trileptal), pregabalin (Lyrica), rufinamide (Banzel), topiramate (Topamax), valproic acid (Depakote) and zonisamide (Zonegran).
How they can cause memory loss: Anticonvulsants are believed to limit seizures by dampening the flow of signals within the central nervous system (CNS). All drugs that depress signaling in the CNS can cause memory loss.
Alternatives: Many patients with seizures do well on phenytoin (Dilantin), which has little if any impact on memory. Many patients with chronic nerve pain find that venlafaxine (Effexor) — which also spares memory — alleviates their pain.
4. Antidepressant drugs (Tricyclic antidepressants)
Why they are prescribed: TCAs are prescribed for depression and, increasingly, anxiety disorders, eating disorders, obsessive-compulsive disorder, chronic pain, smoking cessation and some hormone-mediated disorders, such as severe menstrual cramps and hot flashes.
Examples: Amitriptyline (Elavil), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), imipramine (Tofranil), nortriptyline (Pamelor), protriptyline (Vivactil) and trimipramine (Surmontil).
How they can cause memory loss: About 35 percent of adults taking TCAs report some degree of memory impairment and about 54 percent report having difficulty concentrating. TCAs are thought to cause memory problems by blocking the action of serotonin and norepinephrine — two of the brain's key chemical messengers.
Alternatives: Talk with your health care provider about whether nondrug therapies might work just as well or better for you than a drug. You might also want to explore lowering your dose (the side effects of antidepressants are often dose-related) or switching to a selective serotonin/norepinephrine reuptake inhibitor (SSRI/SNRI). Of the drugs in this category, I find venlafaxine (Effexor) to have the fewest adverse side effects in older patients.
5. Narcotic painkillers
Why they are prescribed: Also called opioid analgesics, these medications are used to relieve moderate to severe chronic pain, such as the pain caused by rheumatoid arthritis.
Examples: Fentanyl (Duragesic), hydrocodone (Norco, Vicodin), hydromorphone (Dilaudid, Exalgo), morphine (Astramorph, Avinza) and oxycodone (OxyContin, Percocet). These drugs come in many different forms, including tablets, solutions for injection, transdermal patches and suppositories.
How they can cause memory loss: These drugs work by stemming the flow of pain signals within the central nervous system and by blunting one's emotional reaction to pain. Both these actions are mediated by chemical messengers that are also involved in many aspects of cognition. So use of these drugs can interfere with long- and short-term memory, especially when used for extended periods of time.
Alternatives: In patients under the age of 50 years, nonsteroidal anti-inflammatory drugs (NSAIDs) are the frontline therapy for pain. Unfortunately, NSAID therapy is less appropriate for older patients, who have a much higher risk of dangerous gastrointestinal bleeding. Research shows the risk goes up with the dosage and duration of treatment.
Talk with your doctor or other health care provider about whether tramadol (Ultram), a nonnarcotic painkiller, might be a good choice for you. In my practice, I often recommend supplementing each 50 mg dose with a 325 mg tablet of acetaminophen (Tylenol). While there are prescription drugs that combine tramadol and acetaminophen, these products have only 37.5 mg of tramadol, and in my practice I've found that patients generally need the larger dose.
6. Parkinson's drugs (Dopamine agonists)
Why they are prescribed: These drugs are used to treat Parkinson's disease, certain pituitary tumors and, increasingly, restless legs syndrome (RLS).
Examples: Apomorphine (Apokyn), pramipexole (Mirapex) and ropinirole (Requip).
How they can cause memory loss: These meds activate signaling pathways for dopamine, a chemical messenger involved in many brain functions, including motivation, the experience of pleasure, fine motor control, learning and memory. As a result, major side effects can include memory loss, confusion, delusions, hallucinations, drowsiness and compulsive behaviors such as overeating and gambling.
Alternatives: If you are being treated for RLS, ask your doctor or pharmacist whether one of your prescription or over-the-counter medications may be the trigger. Potential culprits include many antinausea and antiseizure medications, antipsychotic drugs with tranquilizing effects, some antidepressants, and some cold and allergy medications. In this case, your RLS — and memory problems — could potentially be resolved by simply replacing the offending medication with another drug.
7. Hypertension drugs (Beta-blockers)
Why they are prescribed: Beta-blockers slow the heart rate and lower blood pressure and typically are prescribed for high blood pressure, congestive heart failure and abnormal heart rhythms. They're also used to treat chest pain (angina), migraines, tremors and, in eyedrop form, certain types of glaucoma.
Examples: Atenolol (Tenormin), carvedilol (Coreg), metoprolol (Lopressor, Toprol), propranolol (Inderal), sotalol (Betapace), timolol (Timoptic) and some other drugs whose chemical names end with "-olol."
How they can cause memory loss: Beta-blockers are thought to cause memory problems by interfering with ("blocking") the action of key chemical messengers in the brain, including norepinephrine and epinephrine.
Alternatives: For older people, benzothiazepine calcium channel blockers, another type of blood pressure medication, are often safer and more effective than beta-blockers. If the beta-blocker is being used to treat glaucoma, I recommend talking with your health care professional about potentially using a carbonic anhydrase inhibitor, such as dorzolamide (Trusopt), instead.
8. Sleeping aids (Nonbenzodiazepine sedative-hypnotics)
Why they are prescribed: Sometimes called the "Z" drugs, these medications are used to treat insomnia and other sleep problems. They also are prescribed for mild anxiety.
Examples: Eszopiclone (Lunesta), zaleplon (Sonata) and zolpidem (Ambien).
How they can cause memory loss: Although these are molecularly distinct from benzodiazepines (see No. 1 above), they act on many of the same brain pathways and chemical messengers, producing similar side effects and problems with addiction and withdrawal.
The "Z" drugs also can cause amnesia and sometimes trigger dangerous or strange behaviors, such as cooking a meal or driving a car — with no recollection of the event upon awakening.
Alternatives: There are alternative drug and nondrug treatments for insomnia and anxiety, so talk with your health care professional about options. Melatonin, in doses from 3 to 10 mg before bedtime, for instance, sometimes helps to reestablish healthy sleep patterns.
Before stopping or reducing the dosage of these sleeping aids, be sure to consult your health care professional. Sudden withdrawal can cause serious side effects, so a health professional should always monitor the process.
9. Incontinence drugs (Anticholinergics)
Why they are prescribed: These medications are used to relieve symptoms of overactive bladder and reduce episodes of urge incontinence, an urge to urinate so sudden and strong that you often can't get to a bathroom in time.
Examples: Darifenacin (Enablex), oxybutynin (Ditropan XL, Gelnique, Oxytrol), solifenacin (Vesicare), tolterodine (Detrol) and trospium (Sanctura). Another oxybutynin product, Oxytrol for Women, is sold over the counter.
How they can cause memory loss: These drugs block the action of acetylcholine, a chemical messenger that mediates all sorts of functions in the body. In the bladder, anticholinergics prevent involuntary contractions of the muscles that control urine flow. In the brain, they inhibit activity in the memory and learning centers. The risk of memory loss is heightened when the drugs are taken for more than a short time or used with other anticholinergic drugs.
A 2006 study of oxybutynin ER, for example, found its effect on memory to be comparable to about 10 years of cognitive aging. ("In other words," as the study's lead author put it, "we transformed these people from functioning like 67-year-olds to 77-year-olds.")
Older people are particularly vulnerable to the other adverse effects of anticholinergic drugs, including constipation (which, in turn, can cause urinary incontinence), blurred vision, dizziness, anxiety, depression and hallucinations.
Alternatives: As a first step, it's important to make sure that you have been properly diagnosed. Check with your doctor or other health professional to see if your urinary incontinence symptoms might stem from another condition (such as a bladder infection or another form of incontinence) or a medication (such as a blood pressure drug, diuretic or muscle relaxant).
Once these are ruled out, I'd recommend trying some simple lifestyle changes, such as cutting back on caffeinated and alcoholic beverages, drinking less before bedtime, and doing Kegel exercises to strengthen the pelvic muscles that help control urination.
If these approaches don't work out, consider trying adult diapers, pads or panty liners, which can be purchased just about anywhere. They can be worn comfortably (and invisibly) under everyday clothing and virtually eliminate the risk of embarrassing accidents. In my experience, many patients are reluctant to try this approach, but once over the initial hurdle, come to prefer it for security and peace of mind.
Correction: An earlier version of this article mistakenly implied that mirabegron (Myrbetriq), which the FDA approved last year for the treatment of overactive bladder, is an anticholinergic drug; in fact, it is in a new class of medications called beta-3 adrenergic agonists and is not expected to cause memory loss seen with anticholinergic medications. There currently are no data describing the effect of Myrbetriq on cognition.
10. Antihistamines (First-generation)
Why they are prescribed: These medications are used to relieve or prevent allergy symptoms or those of the common cold. Some antihistamines are also used to prevent motion sickness, nausea, vomiting and dizziness, and to treat anxiety or insomnia.
Examples: Brompheniramine (Dimetane), carbinoxamine (Clistin), chlorpheniramine (Chlor-Trimeton), clemastine (Tavist), diphenhydramine (Benadryl) and hydroxyzine (Vistaril).
How they can cause memory loss: These medications (prescription and over-the-counter) inhibit the action of acetylcholine, a chemical messenger that mediates a wide range of functions in the body. In the brain, they inhibit activity in the memory and learning centers, which can lead to memory loss.
Alternatives: Newer-generation antihistamines such as loratadine (Claritin) and cetirizine (Zyrtec) are better tolerated by older patients and do not present the same risks to memory and cognition.
Ask the Pharmacist is written by Armon B. Neel Jr., PharmD, CGP, in collaboration with journalist Bill Hogan. They are coauthors of Are Your Prescriptions Killing You? (Atria Books).