My father not only had dry age-related macular degeneration. He also had Parkinson’s Disease and the associated cognitive disorder, Lewy Body Dementia.
I never gave a great deal of thought to an association between the two conditions, AMD and Parkinson’s, but it appears other people have. A post in clinicaltrials.gov states they are looking for people with both Parkinson’s and AMD to study – and I quote – “Prevalence of Age-Related Macular Degeneration in Parkinson’s Patients and Assessment of the Role of L-DOPA ( AMD PARK).”
After that, we sort of wade into the deep end of the pool. The brief summary states several studies have shown Parkinson’s patients treated with L-DOPA develop AMD later than untreated patients. A WebMD page from November 12, 2015, reported there was a negative correlation (something increases and then something else decreases) between taking L-DOPA for Parkinson’s and development of AMD. The study did not assume a cause-effect relationship or conclude AMD patients should take L-DOPA.
In the body, L-DOPA becomes dopamine, a neurotransmitter. Dopamine has a myriad of functions in the body including motivation and reward, motor control and photoreceptors functioning.
So far so good. However, the bottom of the pool drops off on me back in the clinicaltrials.gov summary. The summary “explains” L-DOPA is an “endogenous ligand of the GPR43 receptor…located on the RPE’s cell apical pole….It appears L-DOPA, by stimulating this receptor, decreases the cell’s exosome release.”
Of course, it does! Yeah. Good grief!
Ok. Endogenous means it comes from inside. A ligand is…heard that before, hold on…is a molecule that binds to another molecule. Apical means related to the apex and exosome means an extracellular vesicle. GPR43 has something to do with inflammatory signals.
In other words, we are back to the complement immune system. L-DOPA might keep RPEs from signaling for help and accidentally calling in friendly fire on themselves. Maybe. Not only is this me, your ever loyal social scientist, trying to interpret this but they are still doing the research. Stay tuned for further developments before you quote me on these points. This could all be way off the money.
Back to the WebMD article, I discovered I was waaayyyy ahead of the pack in developing my GA. The average age for the development of AMD according to this article was 71. (Gee, nearly ten years ahead of most of the rest of the folks. Here I am. Overachiever. Not!) The average age for those on L-DOPA was 79. (Things that make you say “Hmmmmm…” No wonder they are studying it.)
And another fact just for human interest: both Parkinson’s and AMD are more prevalent in those with red hair. There does seem to be some weird link here. All the scarier because I had natural, red highlights all the years I was growing up. Another hmmmmmm…but we won’t dwell on that.
So, there you have it. There appears to be some sort of connection among Parkinson’s, AMD and, yes, red hair. We are not sure what it is yet, but they are working on it. Maybe L-DOPA will be the new treatment. Stay tuned.
Written September 7, 2018