- 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.
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.’
Advertisement"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:
- Total cortical volume
- Thickness of the temporal lobe cortical
- Inferior and greater lateral ventricle volumes
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 DrugsAnticholinergic 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 DementiaThe 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.
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.
- 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.