Common Allergy Drugs May Raise Dementia Risk

Anticholinergic agents commonly used for colds and allergies have been linked with brain atrophy and dysfunction.

The researchers behind a recent study that found this association suggested that anticholinergic drug use among older adults should be discouraged if no alternative therapy is available.

Lead study author Shannon L. Risacher, PhD, an assistant research professor of radiology and imaging sciences at Indiana University, told Pharmacy Times that pharmacists can certainly put this research finding into practice.

“I would suggest that pharmacists use less anticholinergic medications for OTC allergy relief if possible,” she said. “Loratadine is the best example, but cetirizine has less significant anticholinergic effects, also.”

For older adults seeking sedating antihistamines, Dr. Risacher recommended that pharmacists mention the risks and tell patients to use the medication sparingly and at the lowest effective dose.

“For those who need to take diphenhydramine or other such meds often, I think [pharmacists] might want to advise the patient to see a physician to discuss alternative treatments for their allergies and/or sleep issues,” she added.

Dr. Risacher and her colleagues examined data from 2 longitudinal studies: the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and the Indiana Memory and Aging Study (IMAS).

These studies provided cognitive and neuroimaging data that were collected at regular intervals. The ADNI participants were visited 3, 6, and 12 months after the baseline visit and then annually, while those in the IMAS were followed up with every 18 months after the baseline visit.

A little more than 400 cognitively normal older adults participated in the ADNI and 49 cognitively normal older adults were involved in the IMAS.

One cohort of 52 ADNI participants and 8 IMAS participants took at least 1 medication with medium or high anticholinergic activity, while the other cohort of 350 ADNI participants and 41 IMAS participants didn’t take anticholinergic medications.

The table below shows medications with high anticholinergic activity that pharmacists might want to steer older patients away from or at least recommend short, low-dose treatments.

The 52 patients from the ADNI who took anticholinergic medications had lower mean scores on the Weschler Memory Scale-Revised Logical Memory Immediate Recall and a trail making test. They also had lower executive function composite scores than the other 350 patients from the ADNI.

In addition, those who took anticholinergic medication had reduced total cortical volume and temporal lobe cortical thickness and greater lateral ventricle and inferior lateral ventricle volumes compared with those who weren’t taking the medications.

The researchers also considered that these effects could have been caused by overall morbidity in the patients taking anticholinergics, and so they evaluated the effects of the total number of medications the participants were using and their comorbid conditions. The conditions tested included ischemic attack, myocardial infarction, hypertension, insomnia, and depression.

The researchers looked for differences between the 2 cohorts in terms of medical history and medication use, and then evaluated whether these variables were associated with the outcome variables.

Although they found no significant differences between the 2 groups in terms of age, gender, education, and race, there were some differences regarding the total number of medications, the total number of comorbid conditions, anxiety, and depression. However, only a well-controlled, prospective, longitudinal study could determine true causality, the researchers noted.

Patients taking medication with medium or high anticholinergic effects in the ADNI cohort didn’t perform as well on immediate memory recall and executive function. They also had reduced glucose metabolism, as well as whole-brain and temporal lobe atrophy.

The researchers thought this effect was additive, as more anticholinergic medications was associated with poorer executive function and increased brain atrophy.

To the researchers’ knowledge, this was the first study that looked at the relationship between anticholinergics and brain atrophy and metabolism.