Alzheimer's disease, dementia, depression...: are our eyes the first indicators?
Alzheimer's disease, dementia, depression… What do the eyes see that the brain doesn't yet tell us? The question is no longer rhetorical… In just a few years, research has radically changed the status of the eye in the medical landscape: from a simple sensory organ, it has become a direct window into brain and mental health. For opticians and optical manufacturers, this paradigm shift opens up a horizon far broader than that of visual comfort. We summarize for you what science says today on this subject.
The retina, a direct extension of the brain
Let's begin with a fundamental, often underestimated, anatomical reminder: the retina is part of the central nervous system. It is not connected to the brain—it is a direct extension of it. This biological reality has considerable consequences: visible changes in the eye can reflect, sometimes in advance, changes occurring in brain tissue.
Scientists have found several abnormal proteins in the retina characteristic of Alzheimer's disease , and other abnormalities—such as the thickening or thinning of certain retinal areas—have been linked to the deterioration of small blood vessels in the brain. Optical coherence tomography ( OCT ), already widely used in ophthalmology practices, is emerging as one of the most promising tools for this non-invasive detection.
In addition, there is an even more promising avenue: the detection of beta-amyloid protein deposits in the retina, the same deposits that accumulate in the brains of Alzheimer's patients, sometimes decades before diagnosis. Researchers have used curcumin —a natural reagent that binds to amyloid—to make them visible with OCT. While these techniques are still experimental, they open up a crucial perspective: making the fundus examination a systematic, accessible, non-invasive screening tool that can be integrated into standard eye care.
RetiPhenoAge: Predicting dementia 12 years in advance
In September 2025, an international team of researchers presented RetiPhenoAge , a digital biomarker combining retinal analysis and artificial intelligence, capable of predicting the development of cognitive disorders up to 12 years before the first clinical signs . A standard eye exam could thus one day be sufficient to identify a population to monitor—without lumbar puncture, without PET scan, and at a significantly lower cost.
RetiPhenoAge is based on the analysis of the biological age of the retina, which accurately reflects the overall vascular and neuronal aging of the body. Combined with artificial intelligence algorithms trained on large cohorts, this approach makes it possible to identify discrepancies between chronological age and actual retinal age—a predictive signal of cognitive risk. For manufacturers of ocular imaging products, the message is clear: OCT devices and retinal analysis software are no longer limited to monitoring age-related macular degeneration (AMD) or glaucoma. They could soon constitute the first link in a mass neurological screening program .
It's not yet standard clinical practice, admittedly. But it's the direction research is taking — and it goes directly through the offices and equipment that our sector manufactures and distributes.
Uncorrected vision and dementia: the Lancet verdict
In July 2024, The Lancet Standing Committee on Dementia Prevention published its third report. The conclusion was unequivocal: untreated vision loss is now officially recognized as a modifiable risk factor for dementia , alongside smoking, high blood pressure, and a sedentary lifestyle. It is thought to be linked to approximately 2% of dementia cases in the general population—which, globally, represents millions of people.
The report also specifies that nearly 45% of dementia cases could be prevented or delayed by addressing all 14 identified modifiable risk factors. Among the causes of vision loss are conditions directly treatable by optical and ophthalmological professionals: uncorrected refractive errors, cataracts, and age-related degeneration. Neuroscientist Nikki-Anne Wilson, who led the Australian study that informed these conclusions, states it clearly: identifying and correcting these alterations as soon as they appear could help reduce the likelihood of developing dementia. However, a nuance is important: correcting vision does not treat dementia. But failing to correct it can contribute to accelerating its progression. This shift in perspective should influence public health arguments regarding access to vision care.
The indirect path: isolation, depression, decline
The link between vision and mental health is not solely biological. It also follows well-documented psychosocial pathways. A longitudinal study conducted on the German Ageing Survey (7,108 participants) showed that the onset of significant age-related visual difficulties—such as no longer recognizing a familiar face on the street—is associated with a measurable increase in loneliness and depressive symptoms .
More concerning: US data from the National Health and Aging Trends Study (2,520 adults over 70) indicate that people with both visual and hearing impairments are 4.57 times more likely to experience depression than their peers without sensory deficits. Social isolation—a direct consequence of impaired vision—is itself a known risk factor for dementia, creating a negative cycle that simple optical correction can help break.
Myopia and mental disorders: the link from adolescence
The issue also concerns younger people. A meta-analysis of 2.8 million participants from seven countries, published in 2024, established a significant association between myopia and an increased risk of mental disorders (OR = 1.41). The relationship is bidirectional: mental disorders also appear to increase the likelihood of developing myopia. Another Israeli study conducted on adolescents aged 16 to 20 confirmed significantly higher rates of anxiety and mood disorders among myopic individuals .
The mechanisms at play are multiple. High myopia, in particular, is associated with an increased risk of serious ocular complications (retinal detachment, glaucoma, neovascularization) which can themselves impact quality of life and psychological well-being. Furthermore, environmental factors that promote myopia— excessive screen time, lack of exposure to natural light —are also documented as aggravating factors for anxiety and mood disorders in adolescents. Slowing the progression of myopia from childhood therefore potentially acts on two fronts simultaneously: ocular and mental. These data reinforce the importance of early screening and appropriate correction from childhood—far beyond simple academic performance… 
Image by Anemone123 from Pixabay [/caption]
Optics and mental health: an evolving role
For opticians and optical professionals, this data is an invitation to redefine their role. Vision correction is not merely a convenience service: it is a preventative health measure with documented cognitive and psychological repercussions. Explaining this to a 60-year-old patient or a teenager who is putting off buying new glasses could potentially change the course of their overall health.
For manufacturers, the convergence between retinal imaging, artificial intelligence and early detection of neurodegenerative diseases is shaping a rapidly emerging market — that of non-invasive screening devices integrated into standard vision care pathways.
Seeing better means living better and longer. Science continues to provide proof of this!
Photo Credits:
Cover image by Kohji Asakawa from Pixabay
