Anticholinergic Burden (ACB) Calculator
Anticholinergic burden refers to the cumulative effect of using multiple medications with anticholinergic properties. These drugs work by blocking acetylcholine, a primary neurotransmitter in the central and peripheral nervous systems.
While many drugs are prescribed for non-neurological reasons (such as allergies, bladder control, or depression), their “off-target” anticholinergic effects can accumulate, leading to significant physical and cognitive impairment, particularly in older adults (Boustani et al., 2008).
The Anticholinergic Cognitive Burden (ACB) Scale
The ACB Scale is one of the most clinically validated tools used to quantify a patient’s risk. It categorizes medications into three tiers based on their known effect on cognitive function.
Scoring Criteria
| Score | Description | Example Medications |
| 1 (Mild) | Drugs with serum anticholinergic activity but no clinically noted cognitive effects. | Warfarin, Atenolol, Prednisone, Furosemide |
| 2 (Moderate) | Drugs with established cognitive anticholinergic effects. | Amantadine, Belladonna, Cetirizine |
| 3 (Severe) | Drugs with potent anticholinergic effects (often associated with delirium). | Amitriptyline, Atropine, Diphenhydramine (Benadryl), Oxybutynin |
Calculating the Total Burden
The total ACB score is the sum of the scores for all medications a patient is currently taking.
- A score of $\ge$ 3 is considered clinically significant and is associated with an increased risk of confusion, falls, and long-term cognitive decline (Campbell et al., 2013).
Clinical Consequences of High Burden
Anticholinergic effects are often divided into peripheral and central symptoms:
Peripheral Effects
- Dry Mouth (Xerostomia)
- Blurred Vision (Mydriasis)
- Constipation
- Urinary Retention
- Tachycardia
Central (Brain) Effects
- Impaired Concentration
- Confusion/Delirium
- Increased Fall Risk
- Dementia Risk: Long-term exposure to a high ACB (score of 3+) has been linked in large observational studies to a significantly higher incidence of Alzheimer’s disease and other dementias (Coupland et al., 2019).
Management and Deprescribing
The goal of identifying a high ACB score is not necessarily to stop all medications, but to initiate deprescribing—the planned and supervised process of reducing or stopping medications that may be causing harm.
- Review: Use the ACB scale to audit the medication list.
- Prioritize: Identify “Rank 3” drugs that have safer alternatives (e.g., swapping a sedating antihistamine for a non-sedating one).
- Taper: Many anticholinergic drugs (especially antidepressants and antipsychotics) require a slow taper to avoid withdrawal symptoms.
References
- Boustani, M., et al. (2008). Impact of anticholinergic signals on cognitive function in an elderly population. Aging & Mental Health, 12(5), 528-533. https://doi.org/10.1080/13607860802383040
- Campbell, N., et al. (2013). Use of anticholinergics and the risk of cognitive impairment in an African American population. Neurology, 80(17), 1562-1568.
- Coupland, C. A. C., et al. (2019). Anticholinergic Drug Exposure and the Risk of Dementia: A Nested Case-Control Study. JAMA Internal Medicine, 179(8), 1084-1093. https://doi.org/10.1001/jamainternmed.2019.0677
- Fox, C., et al. (2011). Anticholinergic medication use and cognitive impairment in the older population: The Medical Research Council Cognitive Function and Ageing Study. Journal of the American Geriatrics Society, 59(8), 1477-1483.
