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In the news: What Can MPOD in 1 relatives of AMD patients Tell Us? Vitamin B12 Linked to Lower Parkinson’s Risk

Is MPOD in Close Relatives of AMD Patients an Early Diagnostic Biomarker of AMD?

Studies have found a strong correlation between family history of AMD and development of the disease. It has been shown that AMD risk Is increased by up to 16 times in those having an affected first-degree family member (parents, siblings, children).

Genetic background is also an important determinant of macular pigment optical density (MPOD). Macular pigment is not completely determined genetically, however, so it's possible that MPOD may be modified by dietary intake of lutein and zeaxanthin for protective purposes.

Against this setting, researchers examined how the MPOD in first degree relatives of AMD patients compared with MPOD in healthy controls.

The study(1) included 128 healthy first-degree relatives of AMD patients (group 1) and 74 healthy controls (group 2). The right eyes of all cases were included. MPOD was measured using heterochromatic flicker photometry. Central foveal thickness and subfoveal choroidal thickness were measured with spectral domain OCT.

The demographics of the two groups was similar, though the mean age of the first-degree relatives was slightly higher (49 vs. 42 years).

Mean MPOD values of subjects who were first-degree relatives of patients with AMD were significantly lower than healthy control group (0.43 v. 0.47 respectively, p=.0.048)

Mean central foveal thickness were 208 and 216 mm in group 1 and group 2 respectively (p=0.014), and mean subfoveal choroidal thickness were 232 and 250 mm respectively (p=0.002).

The authors suggest that reduced retinal thickness in subjects without any signs of AMD is likely to reflect possible photoreceptor degeneration due to genetic predisposition to AMD. Also, lower MPOD in Group 1 could be partly a reflection of the lower central foveal thickness in this group.

Further, “choroidal thinning in first-degree relatives may be related to the genetic tendency to atrophy of the microstructure of underlying capillaries and medium-sized vessels”.

According to the authors, theirs is the first study in the literature investigating MPOD values in first-degree relatives of AMD patients. Large, prospective studies are needed to clarify whether lower MPOD values have benefit as a diagnostic biomarker in this population. Such future studies should also measure dietary intake of lutein and zeaxanthin, as well as blood levels of these carotenoids.

Vitamin B12 May Be Protective Against Parkinson’s

Preclinical studies have linked folate, and vitamins B6 and B12. to risk of Parkinson’s disease (PD). B-vitamins have been associated with lower neurotoxicity, better dopamine production, and positively influencing a kinase enzyme (LRRK2) associated with PD.

A new study(2) examining the relationship of long-term intake of these 3 B-vitamins to PD risk in the large-scale Nurses’ Health Study and the Health Professionals Follow-up study, failed to find a link between folate and B6 and PD. However, the highest intake of B12 was associated with a lower risk of PD.

Interestingly, a newly published paper(3) indicates that OCT scans will someday be used by ophthalmologists to screen for Parkinson’s long before symptoms appear.

References

1. Sayin O, et al. Macular pigment optical density in first degree relatives of age-related macular degeneration patients. Curr Eye Res. Published online Aug 2, 2023.
2. M Flores-Torres, et al. Long-term intake of folate, vitamin B6, and vitamin B12 and the incidence of Parkinson's disease in a sample of U.S. Women and Men. Move Disor. 38(5):866-879, 2023.
3. Wagner SK, et al. Retinal optical coherence tomography features associated with incident and prevalent Parkinson disease. Neurol. Open access August 21, 2023