When people diagnosed with Alzheimer’s die and undergo autopsies, researchers have found that almost half of them never had the disease at all. So what is the problem? Why were these people mentally impaired near the end of their lives?

Many doctors believe prescription drugs were causing their confusion, and dementia. Nearly 90 percent of those 65 and older take at least one medication, and many of these drugs can cause cognitive problems.

“It’s crucial to look at the risks versus the benefits of many common medications given to older people,” Jacob Teitelbaum, M.D., author of the best-selling book “Real Cause, Real Cure,” tells Newsmax. “Physicians need to be more careful when prescribing drugs that can cause loss of brain function.”

The common drugs listed below are associated with memory loss and confusion. If you are taking one or more of them — the mental effects are often more severe when they are taken in combination — talk to your doctor about alternatives.

Benzodiazepines such as the popular antianxiety drug Xanax can cloud areas of the brain that affect both short- and long-term memory. Nonprescription alternatives include herbal remedies such as lemon balm and iberogast, a plant-based mixture.

Tricyclic antidepressants or TCAs directly affect brain chemistry and have not been proven to be effective for people with mild to moderate depression. Their use should be reserved for severe cases of depression. Some 35 percent of people taking these drugs report memory loss. If you are taking a TCA, ask your doctor if a lower dosage would be safe.

Narcotic painkillers used to treat chronic pain from rheumatoid arthritis, back pain, or injury affect the chemical messengers to the brain that are involved in cognition. Ask your doctor if you can take a non-narcotic painkiller such as Tramadol.

Beta blockers, commonly used to lower blood pressure, have been associated with cognitive problems. They may “block” key chemical messengers in the brain. Examples include propranolol (Inderal), bisoprolol (Zebeta), nadolol (Corgard), and nebivolol (Bystolic). Try a different class of drugs to treat hypertension such as an ACE inhibitor or calcium channel blocker.

Older antihistamines used to treat or prevent allergy symptoms — Dimetane or Chlor-Trimeton are examples — affect the memory and learning centers of the brain. Substitute newer antihistamines such as Zyrtec or Claritin.

Dopamine agonists are often prescribed to treat restless leg syndrome (RLS) or Parkinson’s disease. Major side effects include memory loss and confusion. Work with your healthcare practitioner or pharmacist to see if your RLS is being triggered by another medication you are taking. Dr. Teitelbaum says sometimes RLS is caused by iron deficiency and will improve or go away if ferritin blood levels are raised with diet or iron supplements.

Nonbenzodiazepine sedative hypnotics or “Z” drugs used for insomnia can not only cause short-term memory loss, they can also cause full-blown amnesia or bizarre behavior. These medications include zolpidem (Ambien), eszopiclone (Lunesta), and zaleplon (Sonata).

Anticholinergics to treat female overactive bladder block the brain messenger acetylcholine, which in turn slows activity in the brain’s memory and learning centers. First, have your doctor rule out possible bladder infections. Cut back on caffeine and alcoholic beverages and practice Kegel exercises to tighten the muscles around the bladder. Also, ask your doctor about a new device called InTone that treats incontinence and may be able to help you.

Antiseizure epilepsy medications are formulated to suppress certain brain functions, which can cause memory loss. Ask your doctor if you can try Dilantin, an antiseizure drug that has less impact on memory. And if you haven’t had a seizure in more than a year, Dr. Teitelbaum suggests that you try a lower dose.