Drugs Linked to Dementia: What Benzodiazepines and Anticholinergics Mean for Your Brain

When it comes to protecting your memory, the usual advice is familiar. It could be: eat well, stay active, sleep enough, and keep your mind engaged. However, there’s another factor many people overlook, which is what’s in their medicine cabinet. In fact, some of the pills people take to sleep better, calm anxiety, or manage allergies are among the drugs linked to dementia in large population studies.

Two medication classes in particular have drawn attention: benzodiazepines and anticholinergics. In both cases, researchers found that long-term use (beyond a few months) was associated with a higher risk of dementia. Moreover, that risk grew as the dose and length of use increased.

Why Doctors Weren’t Surprised

For physicians who care for older adults, these findings confirmed long-standing concerns. For years, the American Geriatrics Society’s Beers Criteria has flagged benzodiazepines, many antihistamines, and tricyclic antidepressants as potentially inappropriate for older patients.

The reason is simple. These drugs can cause confusion, mental fog, and memory lapses. As a result, they raise the risk of falls, broken bones, and car accidents, even before any question of long-term dementia comes up.

What the Research on Drugs Linked to Dementia Found

Before looking at the numbers, keep one point in mind: neither study was a randomized controlled trial. Therefore, the results show an association, not proof that these medications cause dementia.

The Anticholinergic Study

In the first study, published in JAMA Internal Medicine, researchers followed nearly 3,500 adults aged 65 and older enrolled in the Adult Changes in Thought (ACT) study, run by the University of Washington and Group Health in Seattle. Using pharmacy records, the team identified every prescription and over-the-counter drug participants had taken over the previous 10 years.

Over an average follow-up of seven years, about 800 participants developed dementia. Notably, those who used anticholinergic drugs were more likely to be among them. Furthermore, the risk rose with the cumulative dose. Taking an anticholinergic for the equivalent of three years or longer was associated with a 54% higher dementia risk compared with taking the same dose for three months or less.

This study also broke new ground in two ways. First, it was the first to include non-prescription drugs. Second, it ruled out the possibility that people had started these medications to treat early, undiagnosed dementia symptoms. Interestingly, the added risk from anticholinergic bladder medications was just as high as the risk from tricyclic antidepressants.

The Benzodiazepine Study

Meanwhile, a French and Canadian research team reported in The BMJ that benzodiazepine use was associated with a higher risk of an Alzheimer’s diagnosis.

Using Quebec’s health insurance database, the researchers identified nearly 2,000 adults over 66 who had been diagnosed with Alzheimer’s disease. They then compared them with more than 7,000 people of the same age and sex who didn’t have the disease, reviewing prescriptions from the five to six years before diagnosis.

The pattern was clear:

• Three months or less: Risk was roughly the same as for people who had never taken a benzodiazepine.
• Three to six months: Risk of developing Alzheimer’s was 32% higher.
• More than six months: Risk was 84% higher.

In addition, the type of benzodiazepine mattered. Long-acting versions such as diazepam (Valium) and flurazepam (Dalmane) were tied to greater risk than short-acting ones like triazolam (Halcion), lorazepam (Ativan), alprazolam (Xanax), and temazepam (Restoril).

Why Drugs Linked to Dementia Hit Older Adults Harder

Age changes the way the body handles medication. For one thing, the kidneys and liver clear drugs more slowly, so they stay in the bloodstream longer. At the same time, people tend to lose muscle and gain body fat as they get older, which changes how drugs spread through and break down in the body.

Because these medications are stored in fat, their effects can linger for days after the last dose, particularly in people with more body fat. On top of that, older adults often take several prescription and over-the-counter drugs at once, and each one can strengthen or weaken the effects of the others. (For more on this, see our guide to polypharmacy in older adults.)

How These Medications Affect the Brain

Both drug classes act on neurotransmitters, the chemical messengers of the nervous system. Still, they work in different ways.

Anticholinergics block acetylcholine. In the brain, acetylcholine plays a key role in learning and memory. Elsewhere in the body, it helps control blood vessels, airways, heart function, and digestion. The strongest anticholinergics include certain antihistamines, tricyclic antidepressants, overactive bladder medications, and some sleep aids.

Benzodiazepines strengthen GABA. In contrast, benzodiazepines make gamma-aminobutyric acid (GABA), a neurotransmitter that slows brain activity, more powerful. That calming effect is exactly why they’re prescribed for anxiety and insomnia.

What to Do If You Take One of These Medications

If you’re currently taking any of the drugs linked to dementia discussed here, the best first step is a conversation with your doctor. Together, you can weigh the benefits against the risks, revisit why the drug was prescribed, and consider whether a safer alternative might work instead.

Most importantly, don’t stop taking these medications on your own. Quitting most benzodiazepines and anticholinergics abruptly can be unsafe. Instead, work with your clinician on a gradual plan to taper off safely.

The Bottom Line

Ultimately, the research doesn’t say these medications definitely cause dementia. Even so, the consistent link between long-term use and higher risk is a good reason to review your prescriptions regularly, especially after age 65. Knowing which drugs are linked to dementia puts you in a better position to make informed choices with your healthcare provider.

This article is for informational purposes only and is not a substitute for advice from your doctor or another qualified clinician.