What is Anticholinergic Cognitive Burden (ACB)?
An "ACB medication" isn't a single type of drug, but rather any medication that exhibits anticholinergic properties. The term 'ACB' stands for Anticholinergic Cognitive Burden, which refers to the cumulative negative effect on the brain from taking one or more of these drugs. Many common medications, prescribed for a wide range of conditions, have these properties.
Anticholinergic drugs work by blocking acetylcholine, a key neurotransmitter involved in memory, learning, and muscle contraction. While this can be therapeutic, it also leads to side effects such as dry mouth, blurred vision, constipation, and urinary retention. A high anticholinergic burden is associated with more serious central nervous system effects, including confusion, drowsiness, cognitive impairment, increased risk of falls, and potentially dementia, particularly in older adults.
The ACB Scale: Quantifying the Risk
The Anticholinergic Cognitive Burden (ACB) scale is a tool used by clinicians to assess cumulative risk. It assigns a score from 1 to 3 to medications based on their anticholinergic activity and potential for cognitive harm.
- Score of 1 (Possible): Evidence of anticholinergic activity exists, but clinical cognitive effects are limited. Examples include atenolol, diazepam, furosemide, and ranitidine.
- Score of 2 (Definite): Established clinical anticholinergic effects are present. Examples include carbamazepine, cyclobenzaprine, and pethidine.
- Score of 3 (Definite with High Risk): Strong anticholinergic properties and known to potentially cause delirium. Examples include amitriptyline, diphenhydramine (Benadryl), oxybutynin, and paroxetine.
A patient's total ACB score is the sum of the scores of all their anticholinergic medications. A score of 3 or higher is considered clinically significant and indicates an increased risk for adverse outcomes like cognitive decline and falls.
The Impact of a High ACB Score
Research indicates that a high anticholinergic burden can have significant consequences. Long-term use of medications with high ACB scores is linked to an increased risk of developing dementia. Studies have shown that even a single strong anticholinergic taken for a period can increase the odds of developing dementia. A high ACB score is also associated with worse cognitive function over time.
A high anticholinergic burden is also linked to increased risks of falls and fractures, functional impairment, more severe behavioral symptoms in those with dementia, and increased hospitalizations and mortality. Older adults are particularly susceptible due to age-related changes and polypharmacy.
Managing and Reducing Anticholinergic Burden
Managing a patient's ACB is a key part of medication safety. The primary goal is reduction.
1. Medication Review and Deprescribing: A comprehensive review of all medications, including over-the-counter products, is essential to identify all drugs contributing to the ACB score.
2. Switching to Safer Alternatives: Replacing high-ACB drugs with alternatives that have lower or no anticholinergic activity is recommended when possible.
| High-Risk Medication Class | Example(s) to Avoid | Safer Alternative(s) |
|---|---|---|
| First-Gen Antihistamines | Diphenhydramine, Chlorphenamine | Loratadine, Cetirizine, Intranasal Steroids |
| Tricyclic Antidepressants | Amitriptyline, Nortriptyline | Sertraline, Venlafaxine, other SSRIs (except paroxetine) |
| Overactive Bladder Meds | Oxybutynin, Tolterodine | Beta-3 agonists (e.g., Mirabegron), non-pharmacological strategies |
| Muscle Relaxants | Cyclobenzaprine, Orphenadrine | Physical therapy, Acetaminophen |
3. Tapering and Discontinuation: Gradual tapering is often recommended when stopping anticholinergic medications to avoid withdrawal symptoms.
4. Prioritizing Non-Pharmacological Treatments: Non-drug approaches can often reduce or eliminate the need for high-ACB medications for conditions like urinary incontinence, insomnia, and pain.
Conclusion
The Anticholinergic Cognitive Burden is a vital concept in pharmacology, emphasizing the cumulative risk of medications with anticholinergic properties. An "ACB medication" is any drug contributing to this burden. Using tools like the ACB scale allows healthcare providers to identify at-risk patients and make informed decisions to minimize harm. Reducing a high anticholinergic burden through deprescribing, using safer alternatives, and prioritizing non-drug therapies is crucial for protecting cognitive function and overall health, particularly in older adults.
For more information from an authoritative source, you can review the American Geriatrics Society Beers Criteria® for Potentially Inappropriate Medication Use in Older Adults.
