anticholinergic drugs

In a recent study, researchers sought to determine the relationship between anticholinergic drug use and age-related macular degeneration.

In age-related macular degeneration (AMD), the light-sensitive cells at the centre of the eye break down over time, fatty deposits build up, and abnormal blood vessel growth occurs, potentially leading to a loss of vision. It has been suggested that anticholinergic drugs, commonly used for the treatment of depression, allergies, uncontrolled urination, and Parkinson’s Disease, may contribute to AMD as they are associated with the buildup of fatty deposits and with dementia, another symptom of AMD.

In a recent French study published in JAMA Ophthalmology, researchers sought to examine the relationship between anticholinergic drug use and AMD. They enrolled patients with ophthalmologist-diagnosed late-stage AMD in the study. Patients over 60 years of age who were assessed for late-stage AMD but were not diagnosed served as the control group. Those with early-stage AMD were excluded.

What is late-stage AMD?

Late-stage AMD was defined as the presence of geographic atrophy or neovascular AMD. Geographic atrophy is the breaking down of light-sensitive cells in the eye and neovascular AMD nAMD is the abnormal growth of blood vessels under the retina in one or both eyes.

They used medical records and patient interviews to determine the age and date of diagnosis. The first time there was abnormal blood vessel growth was noted, along with the use of anticholinergic drugs and other medications before diagnosis, three months before the trial, and throughout a patient’s entire medical history.

Anticholinergic drug use was classified as “never use”, “ever use”, “previous use” (ending before diagnosis), or “current use” (ongoing at the time of diagnosis). The duration of anticholinergic drug use was classified as non-use, less than 5 years, 5 to 15 years, and greater than 15 years. Age, sex, weight, ethnicity, dietary habits, smoking, alcohol consumption, education, eye colour, the presence of cardiovascular diseases prior to diagnosis, previous eye surgery, and family history of AMD were taken into account.

In total, 200 AMD patients and 200 controls took part in the study. AMD patients were more than twice as likely as controls to be smokers, nearly 60% less likely to drink moderately, and nearly three times as likely to have a family history of AMD. Twenty-six AMD patients (13%) were classified as ever-users compared to 10 controls (5%).

Those who have used anticholinergic drugs were nearly three times more likely to have late-stage AMD compared to never-users

Ever-users were nearly three times as likely as never-users to have late-stage AMD. Those with greater than 15 years of use were nearly six times as likely, and those taking anticholinergic drugs with greater potency were over six times as likely, as non-users to have late-stage AMD.

Ever-use was associated with more than three times the likelihood of geographic atrophy, more than twice the likelihood of neovascular AMD, and nearly three times the likelihood of AMD in one or both eyes as never-use. In contrast, blood thinners and steroidal anti-inflammatory drugs were found to significantly lower AMD risk.

Anticholinergic drugs may be associated with late-stage AMD

The study findings suggest anticholinergic drug use is associated with late-stage AMD. Further, prolonged use with greater potency was found to amplify risk over six-fold. As this study only examined AMD risk, further research will be required to clarify this association, that is,  whether anticholinergic drugs cause or contribute to AMD, or whether AMD produces conditions for which anticholinergic drugs would be prescribed.

Written by Raishard Haynes, MBS

Reference: Aldebert, G. et al. (2018). Association of Anticholinergic Drug Use With Risk for Late Age-Related Macular Degeneration. JAMA Ophthalmol.doi:10.1001/jamaophthalmol.2018.1719

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