Dementia cases could be slashed simply by fixing vison problems with surgery, glasses or contact lenses, scientists say.
The disorder blights the lives of millions worldwide, slowly robbing them of their memories and independence.
But it’s thought about 40 per cent of dementia cases are thought to be preventable, according to the NHS.
Previous research shows that preventing hearing loss, treating depression and doing plenty of exercise are all ways of reducing the risk.
Now scientists at Johns Hopkins University, US, say fixing vision problems could also ward off a fifth of cases.
It’s thought about 40 per cent of dementia cases are thought to be preventable, according to the NHS .
Researchers used data collected annually from a study of US adults age 65 and older and included 2,767 participants eligible for vision and cognitive testing.
The researchers used the strength of association between visual impairment and dementia to calculate the proportion of dementia cases that could be attributed to three types of vison impairment.
Using the data they estimated that 19 per cent of dementia diagnoses in those aged over 71 were attributed to at least one vision impairment — either short sighted, long sighted, or the ability to see small objects sharply and clearly.
Because sight loss can also be caused by diabetes researchers allowed for this in the analysis.
In 15 per cent of dementia cases that were attributed to sight loss, the problem was a difficulty with seeing very small objects, known medically as contrast sensitivity.
Researchers used data collected annually from a study of US adults age 65 and older and included 2,767 participants eligible for vision and cognitive testing
Contrast sensitivity impairment occurs in various eye diseases, most commonly cataracts — where the lens, a small transparent disc inside your eye, develops cloudy patches.
It can be fixed by cataract extraction, a surgical procedure associated with a nearly three per cent decrease in risk of dementia among older adults, according to study authors.
In other cases, ‘best-corrected vision’ should be given in the form of glasses or lens prescriptions to ‘influence visual performance’.
The findings come after hearing loss was ranked at the top of the 12 modifiable risk factors for the global burden of dementia in the 2020 report of the Lancet Dementia Commission.
According to the Alzheimer’s Society, not being able to understand sounds and speech could make the brain work harder.
The charity explains that this additional effort which could lead to changes in the brain that affects our memory and thinking abilities,
Vision impairment was not among the leading modifiable factors of dementia in the Lancet report.
However, experts say that like hearing, vision is a ‘sensory stimulus’ and without it we may be less likely to engage in activities that protect against dementia, including socialising.
Professor Eef Hogervorst from Loughborough University, who was not involved in the study, told The Guardian that in addition to not engaging in activities, sight loss might cause dementia because people who use their eyes less have reduced blood flow to the brain.
Meanwhile, Professor Gill Livingston, a dementia physician at University College London, said brain stimulation is key to keeping your brain fit.
‘Things that make it harder for brain stimulation, like loss of vision and loss of hearing, mean you get less cognitive stimulation,’ she told The i.
There are currently estimated to be 982,000 people with dementia in the UK. This number is expected to rise to 1.4 million by 2040.
An estimated 6.7million Americans age 65 and older are living with Alzheimer’s dementia today.
This number could grow to 13.8 million by 2060.
Alzheimer’s disease is the most common type of dementia, affecting between 50 and 75 per cent of those diagnosed.
