An article by JF Martí Massó,
Neurologist, Emeritus Professor of the UPV/EHU and President of
Visual disturbances in the elderly population increase the risk of falls with the possibility of fractures and significantly alter the quality of life. we know that Alzheimer’s disease (AD) causes visual disorders: decreased sensitivity to color contrast, visual field defects, delayed saccadic eye movements and slow chasing movements, complex visual deficits such as poor comprehension of written words (impaired reading ability), object recognition difficulties and shape, and problems finding objects. Besides, 20% of patients with Alzheimer’s disease experience visual hallucinationsespecially those with vision problems and more severe cognitive impairment.
The AD-related neuropathological lesions have been described in all parts of the visual system. and result in a variety of signs and symptoms. These lesions include deposition of β-amyloid plaques in the lens; reduction in the number of retinal ganglion cells and thinning of the peripapillary retinal nerve fiber layer; optic disc pallor; atrophy and hollowing reduction of axons in the optic nerve; accumulation of lipofuscin in the lateral geniculate nucleus; loss of pyramidal cells in the visual cortex; and the presence of numerous senile plaques in the visual cortex (1).
20% of patients with Alzheimer’s disease experience visual hallucinations, especially those with vision problems and severe cognitive impairment
The posterior cortical atrophy (ACP) is a neurodegenerative condition that affects visual processing pathways and is primarily associated with underlying Alzheimer’s disease pathology, especially in visual association areas. It manifests with visual symptoms such as difficulty reading and driving, lack of attention to one side (hemineglect), disorientation, alterations in writing, in calculation and disorders in the recognition of objects and faces and can be severely disabling since affected patients behave like a functionally blind person.
People with other types of dementia than AD may also have significant visual problems. The dementia with Lewy bodies (MCI) is the second most common type of neurodegenerative dementia and is characterized by parkinsonism, cognitive fluctuations, and vivid visual hallucinations that concur with the onset of cognitive decline. In DCL have been described impairments in multiple visual domains, such as visual construction, the perception of the movement of space and the object, the perception of the orientation of the line and the saccadic movements of the eye. In the post-stroke vascular dementiaup to 30% of patients experience visual disability. The homonymous hemianopsia (especially in occipital strokes) is the most reported symptom, but other disorders have also been described. He Charles Bonnet syndrome it is a common cause of visual hallucinations secondary to poor vision in the elderly population. This is relatively common in age-related macular degeneration.
Several studies have tried to to know if the decrease in visual acuity is a risk factor for cognitive deterioration (2-6). In order to find out if the visual disorder observed in senile macular degeneration and other age-related visual diseases is a risk factor for cognitive deterioration, the following AREDS studies (age-related eye disease study) (5). This is a study that collects data from 11 centers of the macular degeneration (DM) and the related cataract.
The cognitive functions battery was administered to 2,946 participants. The battery consists of 6 neuropsychological tests that measure performance in various cognitive domains. Dunnett’s multiple comparison test was used to identify differences according to MD and severity of visual acuity. The relationship with cognitive impairment was also evaluated using logistic regression. Mean scores on the AREDS Cognitive Functions Battery instruments decreased in individuals with increased macular abnormalities and reduced visual acuity.
After adjustment for age, sex, race, education, smoking, diabetes mellitus, hypertension, and depression, increased macular abnormalities reduced mean cognitive function scores as measured by the Modified Mini Mental State Examination and Memory Scale. Wechsler logic. It was found that reduced vision is associated with reduced mean cognitive function scores as measured by the Modified Mini Mental State Exam and the letter and verbal fluency tasks. The people with vision worse than 20/40 were more likely to have cognitive impairment compared to people with visual acuity of 20/40 or better. These data suggest a possible association of advanced DM and impaired visual acuity with cognitive impairment in older people.
Much attention has recently been paid to deafness as a risk factor for cognitive impairmentpossibly due to the lack of auditory impulses that stimulate the brain (6). More studies are needed to determine if treatment of visual and hearing disturbances can reduce the risk of cognitive and functional decline.
BIBLIOGRAPHY
1: Marquié M, Castilla-Martí M, Valero S, Martínez J, Sánchez D, Hernández I, Rosende-Roca M, Vargas L, Mauleón A, Rodríguez-Gómez O, Abdelnour C, Gil S, Santos-Santos MA, Alegret M, Espinosa A, Ortega G, Pérez-Cordón A, Sanabria Á, Roberto N, Moreno-Grau S, de Rojas I, Simó R, Ciudin A, Hernández C, Orellana A, Monté-Rubio G, Benaque A, Ruiz A , Tárraga L, Boada M. Visual impairment in aging and cognitive decline: experience in a Memory Clinic. Sci Rep. 2019 Jun18;9(1)
2: Swenor BK, Wang J, Varadaraj V, Rosano C, Yaffe K, Albert M, Simonsick EM. Vision Impairment and Cognitive Outcomes in Older Adults: The Health ABC Study. J Gerontol A Biol Sci Med Sci. 2019 Aug 16;74(9):1454-1460.
3: Lee ATC, Richards M, Chan WC, Chiu HFK, Lee RSY, Lam LCW. Higher Dementia Incidence in Older Adults with Poor Visual Acuity. J Gerontol A Biol Sci Med Sci. 2020 Oct 15;75(11):2162-2168.
4: Chen SP, Bhattacharya J, Pershing S. Association of Vision Loss With Cognition in Older Adults. JAMA Ophthalmol. 2017 Sep 1;135(9):963-970.
5: Clemons TE, Rankin MW, McBee WL; Age-Related Eye Disease Study Research Group. Cognitive impairment in the Age-Related Eye Disease Study: AREDS report no. 16. Arch Ophthalmol. 2006 Apr;124(4):537-43.
6: Sardone R, Battista P, Panza F, Lozupone M, Griseta C, Castellana F, Capozzo R, Ruccia M, Resta E, Seripa D, Logroscino G, Quaranta N. The Age-Related Central Auditory Processing Disorder: Silent Impairment of the Cognitive Ear. Front Neurosci. 2019 Jun 14;13:619.