Through a research that could have far-reaching consequences in caring for patients with dementia, scientists at National Institute of Nutrition (NIN) and Bengaluru-based Indian Institute of Science (IISc), have suggested a link between Alzheimer’s disease and cataract.
Scheduled for publication in the journal ‘Bio-Molecular Concepts’, the study of the effects of Alzheimer’s peptides on the eye of rats revealed that these proteins can cause the onset and maturation of cataract. Globally, cataract is recognised as the primary cause of avoidable blindness, with some estimates pointing to a cataract incidence of over 70 per cent in the 60-plus population. As per the data available till June last year, the National Programme for Control of Blindness notes that 11 lakh cataract surgeries were performed last year, of which over one lakh were in Telangana against a target of 2.3 lakh.
In their study, the researchers injected peptides, short chains of amino acids that also make up proteins, seen in deposits on the brain of Alzheimer’s patients into eyes of rats only to notice the onset of cataract a week after the administration. The cataract matured after six weeks in the study rats. Researchers administered two commonly occurring peptides, the amyloid beta 40 and amyloid beta 42.
“We also saw retinal damage occurring in rats injected with peptides. Through earlier studies, we were able to conclude that impairment of a key guardian protein in the lens leading to it become opaque,” said G. Bhanuprakash Reddy of NIN, one of the study’s corresponding authors. “We show that if these Alzheimer’s peptides reach the eye, they can damage it.”
Avadhesha Surolia of IISc, one of the other corresponding authors of the present study and Dr. Reddy had uncovered the mechanism of damage to the eye in the presence of dementia peptides in the past, which paved the way for animal studies. Given that the research of causality between Alzheimer’s and cataract is limited, surgeons in the city cannot seem to concur about it. They, however, say the two conditions are co-morbid in the elderly.
“Both Alzheimer’s and cataract affects the elderly. We do remove cataract on many people with dementia, but to say there is a link needs further research,” said Rajendra Gupta, a senior eye surgeon at the State-run Sarojini Devi Eye Hospital, who was not associated with the study.
- Rohit P.S.