Contrast Sensitivity in Dementia
Contrast sensitivity is the eye’s ability to tell the difference between an object and its background, like seeing a gray sock on a gray carpet. In people with dementia, this skill often weakens early on, making daily tasks harder.
Dementia includes conditions like Alzheimer’s disease, where brain changes affect thinking, memory, and senses. One key change shows up in vision. Studies find low contrast sensitivity in many with mild cognitive impairment, or MCI, which can lead to dementia. For example, only 4 percent of healthy older adults have low contrast sensitivity. That jumps to 20 percent in MCI and 37 percent in Alzheimer’s dementia. This means people with dementia struggle more to spot subtle differences in light and dark.
Why does this happen? Brain areas handling vision and perception get damaged in dementia. In Alzheimer’s, early forgetfulness links to MCI, but soon perception skills fade too. The brain’s trouble processing insulin might play a role, starving neurons of energy needed for clear sight. Eye movement issues also appear, like trouble tracking or fixating on objects, which ties to vision glitches.
This vision loss adds to dementia challenges. Someone might not see steps, food on a plate, or faces clearly, leading to falls, poor eating, or confusion. Hearing loss often pairs with it, hitting 48 percent in Alzheimer’s versus 27 percent in healthy groups. Spotting low contrast sensitivity early could help doctors catch dementia sooner.
Simple checks, like special charts with fading patterns, measure contrast sensitivity. Better lighting, high-contrast colors on walls or dishes, and regular eye exams can ease problems. Families notice these changes before memory woes stand out, offering a clue to get help fast.
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC12740144/
https://www.britannica.com/science/Alzheimer-disease
https://www.frontiersin.org/journals/ophthalmology/articles/10.3389/fopht.2025.1754941/full
