Every time you start a new medication, you weigh the pros and cons. But there’s a question worth adding to that list, especially past middle age: is this medication anticholinergic — and could long-term use affect my brain? A growing body of research has found a consistent, concerning link between this drug class and an increased risk of dementia.
What Anticholinergic Drugs Actually Do
Anticholinergic medications work by blocking acetylcholine, a neurotransmitter involved in both muscle contraction and memory function. They’re used across an enormous range of common conditions — allergies, overactive bladder, depression, motion sickness, muscle spasms,
Parkinson’s disease, and more — which is part of why so many people take one without realizing it. Short-term, the effects (drowsiness, mild memory fog) were long assumed to be reversible once you stopped the medication. Newer research suggests that may not always be true.
The Studies Behind the Concern
The most influential research came from Dr. Shelly Gray at the University of Washington School of Pharmacy, published in JAMA Internal Medicine in January 2015. The team followed 3,434 older adults for up to 10 years, none of whom had dementia at the start of the study.
The results: participants with the highest cumulative anticholinergic use had a 54% higher relative risk of developing dementia, and a 63% higher risk of Alzheimer’s disease specifically, compared with those who didn’t use these drugs. The most commonly implicated medications were older tricyclic antidepressants, first-generation antihistamines like chlorpheniramine, and bladder medications like oxybutynin.
A separate, much larger 2019 study published in the same journal, led by Carol Coupland at the University of Nottingham, examined 58,769 patients diagnosed with dementia alongside more than 225,000 matched controls. It confirmed the association and found that daily use of a strong anticholinergic for at least three years was linked to about a 50% higher chance of a dementia diagnosis — while also identifying which specific anticholinergic drug classes carried the strongest associations: antidepressants, antiparkinson drugs, antipsychotics, bladder antimuscarinics, and antiepileptic drugs.
It’s worth being precise about what this evidence does and doesn’t show: these are observational studies, showing an association, not proof that the drugs directly cause dementia. But the pattern has now shown up consistently across multiple large, independent studies, which is why researchers describe it as a real signal worth taking seriously — not a one-off finding.
Drug Classes With Anticholinergic Effects
Based on the research above and subsequent reviews, these categories carry meaningful anticholinergic activity:
- Bladder/incontinence medications — darifenacin, oxybutynin, tolterodine, flavoxate
- Muscle relaxants — cyclobenzaprine, dicyclomine, orphenadrine
- Certain narcotic pain relievers — meperidine
- Some anticonvulsants — carbamazepine, oxcarbazepine
- Parkinson’s medications — benztropine, procyclidine, trihexyphenidyl
- Tricyclic antidepressants — amitriptyline, amoxapine, clomipramine, doxepin, imipramine, nortriptyline
- Certain antipsychotics — clozapine, olanzapine, quetiapine, thioridazine
- First-generation allergy medications (antihistamines) — diphenhydramine, chlorpheniramine, hydroxyzine, promethazine
- Motion sickness medications — dimenhydrinate, meclizine, scopolamine
Separately, some research has also pointed to a possible association between long-term benzodiazepine use (common for anxiety and insomnia) and dementia risk — though this evidence is less consistent, and the field is still actively debating how much of that link reflects true causation versus other confounding factors, such as anxiety or insomnia themselves being early symptoms of undiagnosed cognitive decline.
What This Means for You — And What It Doesn’t
This is not a green light to stop any of these medications on your own. Several of the drug classes above treat conditions where stopping suddenly can be genuinely dangerous — anticonvulsants prevent seizures, antipsychotics manage serious psychiatric conditions, and Parkinson’s medications control motor symptoms that can worsen sharply without them. Abruptly discontinuing any of these can carry far more immediate risk than the long-term dementia association itself.
What the research does support is a conversation with your doctor or pharmacist, especially if you’re taking one of these medications regularly and are over 65 — the age group where these studies focused and where the risk appears most pronounced. Useful questions to bring to that conversation:
- Is there a lower-anticholinergic-burden alternative for my condition? For common, lower-stakes cases, alternatives do exist — Dr. Gray herself noted that a second-generation antihistamine like loratadine can often replace an older allergy medication like chlorpheniramine, and an SSRI can sometimes replace an older tricyclic antidepressant for depression.
- Am I on more than one anticholinergic medication at once? Cumulative “anticholinergic burden” across multiple drugs matters, so a pharmacist reviewing your full medication list can catch overlaps you might not notice.
- What would tapering or switching actually look like, if a change makes sense for my specific condition?
For medications treating minor, situational issues — occasional allergies, occasional sleeplessness — there’s often real room to reduce use. For medications treating serious neurological or psychiatric conditions, that decision belongs to you and your prescribing doctor, not a blog post or a supplement aisle.
The Bottom Line
The link between long-term, high-dose anticholinergic use and dementia risk is one of the more well-replicated findings in this area of research, backed by large studies spanning tens of thousands of patients.
But nuance matters here more than almost anywhere else: this is population-level risk data, not a guarantee for any individual, and for many of the conditions these drugs treat, the medication itself is protecting against a more immediate and serious harm. The right move is an informed conversation with your doctor about your specific medications — not stopping cold on your own.
References
- Gray, S. L., et al. “Cumulative Use of Strong Anticholinergics and Incident Dementia: A Prospective Cohort Study.” JAMA Internal Medicine, 2015.
- National Institute on Aging — “Use of Anticholinergic Drugs Linked to Higher Dementia Risk”
- Coupland, C. A. C., et al. “Anticholinergic Drug Exposure and the Risk of Dementia: A Nested Case-Control Study.” JAMA Internal Medicine, 2019.
- Campbell, N. L., and Boustani, M. A. “Adverse Cognitive Effects of Medications: Turning Attention to Reversibility.” JAMA Internal Medicine, 2015 (invited commentary).
- University of Washington School of Pharmacy — “Higher Dementia Risk Linked to More Use of Common Drugs”
- Neurology Today (American Academy of Neurology) — “Anticholinergics Found to Be Associated with Risk of Dementia, Study Suggests”
