Anticholinergic medications are widely used to treat a variety of health conditions, but their effects on memory and cognition have raised significant concerns, especially in older adults1 . Research shows that long-term use of these drugs is linked to an increased risk of dementia and cognitive decline2 . Understanding how these medications work and their potential side effects is essential for safe use and minimizing risks3 .
How Anticholinergics Work
Anticholinergic drugs block the action of acetylcholine, a neurotransmitter that plays a key role in the parasympathetic nervous system, which controls bodily functions during rest and relaxation4 . By blocking acetylcholine at muscarinic receptors in both the central nervous system (CNS) and peripheral nervous system (PNS), these drugs reduce nervous system activity related to involuntary muscle movements and other bodily functions5 . In the CNS, this blockade can impair attention, decrease learning ability, and cause memory difficulties5 . In the PNS, anticholinergics affect muscles in the gastrointestinal tract, lungs, urinary tract, and eyes, leading to side effects such as pupil dilation, slowed gastrointestinal contractions, urinary retention, constipation, and changes in heart rate4 .
Anticholinergic drugs generally take effect within minutes to a few hours after administration4 . Because acetylcholine is involved in regulating many bodily functions, blocking its action can have widespread clinical implications, particularly in older adults whose acetylcholine production naturally declines with age2 .
💡 Did You Know? Anticholinergic drugs interfere with how your body uses acetylcholine, a neurotransmitter essential for memory and muscle control. Over 600 medications have anticholinergic effects6 .
Common Anticholinergic Drug Types
Anticholinergic medications are used to treat a broad range of conditions, including allergies, depression, nausea, muscle spasms, Parkinson's disease, overactive bladder, and respiratory disorders such as asthma and chronic obstructive pulmonary disease (COPD) 51. Many medications have anticholinergic properties either as their primary action or as a side effect4 .
Examples of anticholinergic drugs and their uses include:
- Atropine: Treats slow heartbeat (bradycardia) and certain types of poisoning6 .
- Benztropine and Trihexyphenidyl: Used for Parkinson's disease and parkinsonism to reduce muscle tremors6 .
- Diphenhydramine: Commonly found in over-the-counter allergy and sleep aid medications6 .
- Glycopyrrolate: Reduces salivation during medical procedures and treats severe drooling6 .
- Ipratropium and Tiotropium: Help manage symptoms of asthma and COPD6 .
- Oxybutynin and Tolterodine: Treat muscle spasms and urge incontinence related to bladder conditions6 .
- Scopolamine: Eases nausea and vomiting associated with motion sickness6 .
Many other medications, such as tricyclic antidepressants, antipsychotics, and certain antihistamines, have mild to moderate anticholinergic properties as side effects4 . Most anticholinergics are taken orally, but some are administered via inhalation or injection depending on the condition being treated4 .
Memory and Cognitive Side Effects
Anticholinergic medications can cause significant cognitive side effects, especially in older adults. These effects include confusion, memory loss, difficulty concentrating, and impaired reasoning5 2. The risk of cognitive decline increases with the cumulative anticholinergic burden—the total effect of taking multiple medications with anticholinergic properties5 . Studies have found that long-term use of anticholinergic drugs is associated with a higher risk of dementia, with a 54% increased risk observed in people taking these medications for three years or more compared to shorter use2 3.
“Our findings suggest that reducing the use of anticholinergic drugs before people develop any cognitive problems may be an important way to prevent the negative consequences of these drugs on thinking skills, especially for people who have an elevated risk of developing Alzheimer's disease.”
— Lisa Delano-Wood, University of California, San Diego9
Older adults are particularly vulnerable because their bodies produce less acetylcholine naturally, and their blood-brain barrier becomes more permeable, allowing more of the drug to enter the brain1 . Additionally, aging slows the clearance of drugs by the liver and kidneys, increasing the risk of side effects2 . People with dementia or mild cognitive impairment are even more sensitive to these adverse effects7 .
Common cognitive and neurological side effects of anticholinergics include:
- Confusion and delirium8
- Memory problems and difficulty learning new information5
- Sedation and drowsiness7
- Behavioral changes, agitation, and hallucinations1
- Increased risk of falls and fractures due to impaired balance and cognition2
“Future studies are needed to see if indeed stopping the use of these drugs could lead to a reduction in mild cognitive impairment and Alzheimer's disease down the road.”
— Lisa Delano-Wood, University of California, San Diego9
Important Usage Considerations
Anticholinergic medications can cause a range of side effects, from mild to severe. Mild side effects include dry mouth, dry eyes, and blurred vision, which often resolve quickly after stopping the medication4 . Severe side effects can include urinary retention, ileus (intestinal blockage), confusion, and increased body temperature due to decreased sweating5 4.
Older adults and people with underlying health conditions are at higher risk of experiencing severe side effects5 . The American Geriatrics Society Beers Criteria recommends minimizing the use of anticholinergic drugs in older adults because of these risks5 . Higher doses and cumulative use of multiple anticholinergic medications increase the likelihood of adverse effects4 .
When considering anticholinergic medications, it is important to:
- Review all current medications, including over-the-counter drugs, for anticholinergic properties5 .
- Use the lowest effective dose to minimize side effects4 .
- Monitor for new or worsening side effects, especially cognitive changes4 .
- Consider alternative treatments with less anticholinergic activity when possible5 .
| Common Side Effects | Description | Risk Factors |
|---|---|---|
| Dry mouth and dry eyes | Reduced saliva and tear production | Older age, higher doses4 |
| Blurred vision and pupil dilation | Difficulty focusing and light sensitivity | CNS effects, older adults4 |
| Urinary retention | Difficulty urinating | Men with prostate issues, elderly5 |
| Confusion and memory problems | Cognitive impairment and delirium | Older adults, dementia patients7 |
| Constipation and slowed digestion | Reduced gastrointestinal motility | Higher doses, multiple meds4 |
When to Contact Your Doctor
It is important to consult your healthcare provider if you experience any new or worsening side effects while taking anticholinergic medications. Older adults, especially those aged 65 and older, are at increased risk for serious adverse effects such as cognitive decline, falls, heart problems, and even mortality5 4. People with underlying health conditions face even greater risks4 .
“This is of course concerning and is a potential area for improvement that could possibly lead to a reduction in cases of mild cognitive impairment.”
— Lisa Delano-Wood, University of California, San Diego9
You should contact your doctor if you notice:
- Difficulty urinating or urinary retention4
- Confusion, memory loss, or sudden changes in mood or behavior5
- Severe constipation or abdominal pain4
- Dizziness or increased risk of falls2
- Dry mouth or eyes that do not improve4
Experts advise minimizing anticholinergic use in older adults and considering safer alternatives when possible4 . Newer medications with less anticholinergic activity are available for many conditions, such as fluoxetine for depression, quetiapine for schizophrenia, cetirizine for allergies, and levodopa for Parkinson's disease4 .
“It is also a possible target toward a future precision medicine approach because we can more carefully consider and prescribe medications for people depending upon their risk profile for neurodegenerative disorders like Alzheimer's disease.”
— Lisa Delano-Wood, University of California, San Diego9
Key Points Summary
- Anticholinergic drugs block acetylcholine, affecting both the central and peripheral nervous systems, which can impair memory and attention5 4.
- These medications are used to treat many conditions, including allergies, Parkinson's disease, bladder disorders, and respiratory diseases6 .
- Long-term and cumulative use of anticholinergics is linked to an increased risk of dementia and cognitive decline, especially in older adults2 3.
- Side effects range from mild (dry mouth, blurred vision) to severe (confusion, urinary retention, ileus), with higher risks in older adults and those with health conditions5 4.
- Always review your medications with a healthcare provider to identify anticholinergic effects and discuss safer alternatives when possible5 4.
