Over-the-Counter Anticholinergic Drugs Exacerbate Dementia Risk

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• The use of some common drugs has been associated with decreased brain size.
• Anticholinergics that are responsible for transferring electrical impulses between nerves have been found to lower metabolism and increase risk for Alzheimer's and dementia.
• The study participants showed lower brain volume with larger cavities inside the brain.

Over the counter drugs like the ones for hay fever and asthma could increase the risk for dementia when consumed for a prolonged period, urging senior adults to reconsider their drug choices.

A new study by Dr Shannon L. Risacher and colleagues focuses on the effects of anticholinergic drugs on brain volume and brain activity, a first of its kind study where the effects of commonly used drugs on brain activity are studied.

‘Drugs used for hay fever medication, asthma and sleeping pills can lead to reduced brain size and cognition in senior adults.’

"These findings provide us with a much better understanding of how this class of drugs may act upon the brain in ways that might raise the risk of cognitive impairment and dementia." said Dr Shannon Risacher, who is an assistant professor of radiology and imaging sciences and first author of the paper.

The study assessed the association between the use of anticholinergic drugs and glucose metabolism, brain atrophy and cognition among cognitively normal adults. Data for the study was collected from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and The Indiana Memory and Aging Study (IMAS).

About 409 participants were included in the ADNI study and after the first baseline study, the study participants were checked after 3,6 and 12 months, after than annually. Among them, 52 participants took anticholinergic drugs while 350 participants did not take anticholinergic drugs.

In the IMAS study, 49 study participants were included in the study with 8 participants taking anticholinergic drugs while 41 participants didn't. After the initial baseline study, the participants were checked every 18 months.

The duration of the study was as long as 4 years for many participants. Participants who took anticholinergic drugs were found to have lower:

• Memory
• Total cortical volume
• Thickness of the temporal lobe cortical
• Inferior and greater lateral ventricle volumes

The study results found that there was a sharp clinical decline in the size of the brain with increased brain atrophy and dysfunction. The research provides evidence that the use of cholinergic drugs can lead to cognitive decline, especially in older adults and so alternative drugs should be used for treatment. There was a statistically significant increase in risk for cognitive decline by 54% for older adults who took anticholinergic drugs and 63% increased risk of Alzheimer's.

Though there have been studies that were conducted earlier to analyze the association between prolonged drug usage and cognitive decline, this is the first study that looks at the biological pathways that lead to the decline, using neuro-imaging techniques.

Dr Risacher further states that "These findings might give us clues to the biological basis for the cognitive problems associated with anticholinergic drugs, but additional studies are needed if we are to truly understand the mechanisms involved".

Anticholinergic Drugs

Anticholinergic drugs act on muscles around the bronchi. When there is lung irritation, the muscles around the bronchi tighten resulting in narrow bronchi. Anticholinergic drugs act on these muscles and prevent narrowing of the bronchi.

This study by Dr Risacher has found that over-the-counter anticholinergic drugs are used for hay fever, asthma and even sleeping pills. Older adults who have been using drugs like Benadryl, Nytol and Piriton for 3 years have more than 60% chance of developing Alzheimer's.

The reason behind the increased risk for Alzheimer's is believed to be due to these drugs blocking the release of acetylcholine which is necessary for the transmission of electrical signals between nerve cells. In Alzheimer's, there is lowered level of acetylcholine, therefore, these drugs may lead to aggravation of the condition or could trigger the condition in the elderly.

Dosages that Increase Risk for Dementia

The study found that:

• 10mg/day of doxepin
• 4mg/day of diphenhydramine
• 5mg/day of oxybutynin for more than three years increase the risk of dementia.

Older patients who require these drugs for treatment should be monitored closely. The lowest dosage that provides the required relief should be administered for the patients and the progress of the treatment closely recorded. Alternate drugs that do not produce cognitive decline should then be used to protect the cognitive abilities of the patient.

Since many of these drugs are available over the counter, it is difficult for doctors to monitor their usage by older adults. However, the conclusive evidence provided by this research warrants better awareness among senior citizens to prevent cognitive decline.

Here are some tips for the elderly to follow as a result of this research:

• Check with a doctor about medications for hay fever, asthma or any ailment instead of self-medicating.
• Do not stop any medication till the doctor is consulted.
• Ask for alternate medications.

References:

1. Shannon L. Risacher, PhD1,2; Brenna C. McDonald, PsyD, MBA1,2,3; Eileen F. Tallman, BS1,2; and colleagues "Association Between Anticholinergic Medication Use and Cognition, Brain Metabolism, and Brain Atrophy in Cognitively Normal Older Adults" JAMA Neurol. Published online April 18, 2016.
2. http://www.thoracic.org/copd-guidelines/for-patients/what-kind-of-medications-are-there-for-copd/what-are-anticholinergic-medications.php

Source: Medindia

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