Related Experiment Video
Updated: Aug 12, 2026
09:45
Motor and Hippocampal Dependent Spatial Learning and Reference Memory Assessment in a Transgenic Rat Model of Alzheimer's Disease with Stroke
Published on: March 22, 2016
Alzheimer-like visual deficits in Down syndrome
F J Rocco1, A Cronin-Golomb, F Lai
1Department of Psychology, Boston University, MA 02215, USA.
Alzheimer Disease and Associated Disorders
|June 1, 1997
Summary
Adults with Down syndrome (DS) exhibit visual deficits similar to Alzheimer disease (AD), including impaired color vision and reduced contrast sensitivity. These Alzheimer-like visual impairments in DS may occur independently of age-associated dementia.
Area of Science:
- Neuroscience
- Ophthalmology
- Genetics
Background:
- Alzheimer disease (AD) is characterized by specific visual impairments.
- Down syndrome (DS) frequently exhibits Alzheimer neuropathology by age 40.
- Investigating visual profiles in DS can elucidate AD-related visual changes.
Purpose of the Study:
- To determine if adults with Down syndrome (DS) display the characteristic visual impairment profile seen in Alzheimer disease (AD).
- To compare visual function in individuals with DS to those with mental retardation (MR) of other etiologies.
Main Methods:
- Tested color discrimination, stereoacuity, and contrast sensitivity in 22 adults with DS and 18 adults with MR.
- Utilized standardized tests for visual function assessment.
- Analyzed data for differences between DS and MR groups and correlations with age.
Main Results:
- DS subjects showed significantly more tritanomalous errors (blue hue discrimination deficiency) than expected by chance (p < 0.05).
- DS subjects had poorer stereoacuity (p < 0.01) and reduced contrast sensitivity across frequencies (p < 0.01) compared to MR subjects.
- No correlation was found between visual performance and age in DS subjects.
Conclusions:
- Adults with Down syndrome exhibit an Alzheimer disease-like visual deficit profile.
- These visual impairments in DS may stem from pathological changes in visual cortex areas, similar to AD.
- The findings suggest that AD-like visual deficits in DS can manifest independently of age-associated dementia.
Related Concept Videos
01:26Alzheimer's Disease: Overview
Alzheimer's Disease (AD) is a continually advancing neurodegenerative disorder, distinguished by escalating memory loss, cognitive dysfunction, and dementia. The disease unfolds in three stages: preclinical, mild cognitive impairment (MCI), and dementia. Its onset is insidious, and the progression gradual, with the cause not well explained by other disorders.
The clinical diagnosis of AD hinges on the presence of memory and other cognitive impairments. Biomarkers, such as changes in Aβ and tau...
The clinical diagnosis of AD hinges on the presence of memory and other cognitive impairments. Biomarkers, such as changes in Aβ and tau...
01:12Visual Agnosia
Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round end"...
01:30Dementia
Dementia is a collective term for cognitive disorders primarily affecting memory, thinking, and reasoning. It is not a specific disease but a syndrome, with Alzheimer's disease being the most common cause, accounting for approximately 60-80% of cases. Other types include vascular dementia, Lewy body dementia, and frontotemporal dementia. Dementia affects millions worldwide, particularly older adults, though it is not a normal part of aging.
The progression of dementia is generally gradual.
The progression of dementia is generally gradual.
01:29Alzheimer Disease l: Introduction
Alzheimer disease is a chronic, progressive, and irreversible neurodegenerative disorder and the most common cause of dementia in older adults. It leads to gradual neuronal loss, causing cognitive decline, behavioral changes, and loss of functional independence.Risk Factors and EtiologyThe disease is multifactorial. Age is the strongest risk factor, with prevalence doubling every 5 years after age 65. Genetic factors include mutations in genes such as APP, PSEN1, and PSEN2, which are associated...
01:23Alzheimer Disease ll: Pathophysiology
Alzheimer disease involves structural changes in the brain that begin long before symptoms appear. The most distinctive features are extracellular neuritic plaques and intracellular neurofibrillary tangles.Neuritic plaques form in the cerebral cortex and around blood vessels. These plaques contain a dense core of beta-amyloid (Aβ)—a toxic protein fragment that clumps outside neurons. The core is surrounded by damaged neuronal extensions, as well as reactive astrocytes and microglia. Abnormal...
01:22Dementia l: Introduction
Dementia is an acquired, progressive syndrome characterized by a decline in multiple cognitive domains severe enough to impair daily functioning and reduce independence. Although memory loss is a central feature, the diagnosis requires additional deficits involving language, executive function, visuospatial skills, judgment, calculation, or abstract reasoning. These cognitive impairments reflect underlying neurodegenerative or vascular processes that gradually disrupt neuronal networks...