A

Abnormal amyloid accumulation

One of the hallmarks of Alzheimer's disease is the accumulation of amyloid plaques between nerve cells (neurons) in the brain. In a healthy brain, these protein fragments are broken down and eliminated. In Alzheimer's disease, the fragments accumulate to form hard, insoluble plaques.

Age-Related Eye Disease Study (AREDS)

The primary goal of the Age-Related Eye Disease Study (AREDS) was to determine if a daily intake of certain vitamins and minerals could reduce the risk of cataract and advanced age-related macular degeneration (AMD). When the trial ended, in 2001, AREDS showed that a specific formula of nutritional supplements containing high doses of antioxidants and zinc could slow the disease in those who have intermediate AMD and those with advanced AMD in only one eye. The AREDS supplement contains beta-carotene, which could be a health hazard to smokers.

Age-Related Eye Disease Study2 (AREDS2)

The follow-up study to Age-Related Eye Disease Study (AREDS) was published in 2013. AREDS2 determined that the antioxidants lutein and zeaxanthin proved safer than the beta-carotene used in the original AREDS study. AREDS2 also found that the addition of omega-3 fatty acids to the special formula did not improve the formula’s success

Age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is an irreversible destruction of the central area of the retina, called the macula. The retina is the  light sensitive layer of tissue that lines the back of the eye and transmits visual information via the optic nerve to the brain. Macular degeneration leads to loss of the sharp, fine-detail, “straight-ahead” vision required for activities like reading, driving, recognizing faces, and seeing the world in color.

Amblyopia

When vision in one of the eyes is reduced because the eye and the brain are not working together properly, it is called amblyopia, or lazy eye.

Amsler grid

The Amsler grid, which looks like a piece of graph paper with a small dot in the center, can help detect early signs of retinal disease and monitor changes in vision after diagnosis.

Amyloid

Amyloid is a general term for protein fragments that the body produces normally. Beta amyloid is a protein fragment snipped from an amyloid precursor protein (APP). In a healthy brain, these protein fragments are broken down and eliminated. In Alzheimer's disease, the fragments accumulate to form hard, insoluble plaques.

Amyloid beta (Aβ) peptide

Evidence points to beta amyloid (Aβ) peptide accumulation as a culprit in preclinical Alzheimer’s disease.

Amyloid plaques

One of the hallmarks of Alzheimer's disease is the accumulation of amyloid plaques between nerve cells (neurons) in the brain. Amyloid is a general term for protein fragments that the body produces normally. Beta amyloid is a protein fragment snipped from an amyloid precursor protein (APP). In a healthy brain, these protein fragments are broken down and eliminated. In Alzheimer's disease, the fragments accumulate to form hard, insoluble plaques.

Amyloid-beta deposits

Amyloid is a general term for protein fragments that the body produces normally. Beta amyloid is a protein fragment snipped from an amyloid precursor protein (APP). In a healthy brain, these protein fragments are broken down and eliminated. In Alzheimer's disease, the fragments accumulate to form hard, insoluble plaques.

Angiogenesis

Angiogenesis is the growth of new blood vessels in the body.

Angle

The drainage “angle” is the area where the cornea (the clear part in the front of the eye) meets the iris (the colored part of the eye). The “angle” is also where the trabecular meshwork is located.

Angle-closure glaucoma

Angle-closure glaucoma, also called narrow-angle glaucoma, may be acute or chronic. In acute angle-closure glaucoma, the normal flow of eye fluid (aqueous humor) between the iris and the lens is suddenly blocked. Symptoms may include severe pain, nausea, vomiting, blurred vision, and seeing a rainbow halo around lights. Chronic angle-closure glaucoma progresses more slowly and can damage the eye without symptoms, similar to open-angle glaucoma.

Anti-amyloid therapy

Anti-amyloid agents can decrease the production of beta-amyloid, prevent the accumulation of beta-amyloid, or increase removal of beta-amyloid from the brain.

Anti-vascular endothelial growth factor (anti-VEGF)

A current treatment option for wet age-related macular degeneration (AMD). An eye injection with drugs that help to slow vision loss by reducing the availability of excess VEGF protein (thus, cutting off the growth of leaky, damaging blood vessels). Includes: such as Lucentis® (ranibizumab), Macugen (pegaptanib), Eylea® (aflibercept) and Avastin® (bevacizumab).

Apolipoprotein E (apoE)

A gene called Apolipoprotein E (ApoE) appears to be a risk factor for the late-onset form of AD. There are three forms of this gene: ApoE2, ApoE3 and ApoE4. Roughly one in four Americans has ApoE4 and one in twenty has ApoE2. While inheritance of ApoE4 increases the risk of developing AD, ApoE2 substantially protects against the disease.

Autophagy

Autophagy is derived from two Greek words “auto” meaning self and “phagy” meaning eating. It is a normal cellular housekeeping function similar to “taking out the trash.” It’s one of the ways cells have of recycling or eliminating unwanted substances.

Axons

The axon is also known as a nerve fiber, and it functions to transmit nerve impulses away from the nerve cell body to different neurons, muscles and glands.

B

Beta amyloid

Amyloid is a general term for protein fragments that the body produces normally. Beta amyloid is a protein fragment snipped from an amyloid precursor protein (APP). In a healthy brain, these protein fragments are broken down and eliminated. In Alzheimer's disease, the fragments accumulate to form hard, insoluble plaques.

Brain atrophy

Shrinkage of the brain caused from neural damage and neuron cell loss, resulting in a measurable loss of brain volume. 

C

Cerebellum

The part of the brain responsible for regulation of motor control, such as coordination and timing.

Cerebral cortex

The cerebral cortex is the outer layer of brain tissue, and is responsible for many "higher-order" functions like language and information processing.

Cerebrospinal fluid (CSF) measurements

Cerebrospinal fluid (CSF) collection is a test to examine the fluid that surrounds the brain and spinal cord. Scientists are measuring proteins in the CSF to see if they can predict if someone will develop Alzheimer’s disease years before the first symptoms appear.

Cholinesterase inhibitors

Cholinesterase inhibitors address the low levels of acetylcholine, an important brain chemical, in people with Alzheimer's. The medications slow down this chemical breakdown of acetylchole, which in turn may slow down the progression of cognitive symptoms.

Choroid

The choroid is the layer of the eye behind the retina, which contains blood vessels that nourish the retina.

Choroidal neovascularization

Choroidal neovascularization is the out-of-control growth of fragile, leaky blood vessels that distort vision and damage the retina, which is seen in both diabetic retinopathy and the “wet” form of age-related macular degeneration (AMD).

Ciliary body

Eye fluid (aqueous humor) is produced by the ciliary body where it flows into the front part of the eye, called the anterior chamber. The eye fluid then flows out through a spongy tissue called the trabecular meshwork into a drainage canal.

Cognitive reserve

Cognitive reserve is the brain's capacity to compensate for damage.

Congenital glaucoma

Congenital glaucoma affects babies and young children born with defects that prevent the normal drainage of fluid from the eye.

Corticobasal degeneration

Corticobasal degeneration is a progressive neurological disorder characterized by nerve cell loss and atrophy (shrinkage) of various regions of the brain, including the cerebral cortex and the basal ganglia (which helps to start and control movements, as well as other functions).

D

Degeneración corticobasal

La degeneración corticobasal es un trastorno neurológico progresivo que se caracteriza por la pérdida de células nerviosas y la atrofia (contracción) de varias regiones del cerebro, incluyendo la corteza cerebral y los ganglios basales (lo cual ayuda a iniciar y controlar los movimientos, así como otras funciones).

Dementia

Dementia is group of symptoms that are associated with a decline in thinking, reasoning, and/or remembering. Alzheimer's disease is the most common form of dementia.

Drusen deposits

Drusen are tiny protein and fat deposits in the retina that, when detected through a dilated eye exam, are a hallmark sign of the early stages of age-related macular degeneration (AMD).

Dry macular degeneration

In dry macular degeneration, the most common form of this eye disease, yellowish cellular deposits called drusen (extracellular waste products from metabolism) form under the retina. An increase in the size and number of drusen is often the first sign of dry macular degeneration. Dry macular degeneration can cause slightly blurred central vision, and this area grows larger as the disease progresses. Blind spots may develop, and people normally have more difficulty seeing color and fine detail.

E

Early-onset Alzheimer's

Familial or early-onset Alzheimer's disease is inherited and develops in people between the ages of 30 and 60. If even one of three gene mutations that causes the disease is inherited from a parent, the child will almost certainly develop Alzheimer's disease. However, less than five percent of patients have early-onset Alzheimer's disease. 

Extracellular matrix (ECM)

Molecules lying outside of cells that provide structural and biochemical support to surrounding cells.

F

Fibroblast growth factor (FGF) proteins

A family of "signaling proteins" involved in tissue formation. Some are involved in angiogenesis (the growth of new blood vessels).

G

Genome-wide association studies (GWAS)

GWAS use rapid gene scanning technologies to locate DNA fragments that reflect variations in sequencing, known as SNPs (single-nucleotide polymorphisms) and may be associated with a disease. GWAS are ideally suited for studying complex diseases as a way of approximating and locating the genetic contribution.

Geographic atrophy

In advanced dry macular degeneration, there are regions of retinal cells waste away and die (atrophy). Sometimes these regions of atrophy looks like a map to the doctor who is examining the retina, hence the term “geographic atrophy.”

Glaucoma suspect

A glaucoma suspect is a person who has  normal eye pressure but their visual field or optic nerve looks suspicious for glaucoma.

Goniotomy

Goniotomy is used almost exclusively for infants with congenital glaucoma. In this procedure, a tiny blade or laser is use to cut the trabecular meshwork (the spongy tissue that serves as the eye's primary drainage channel for aqueous humor). This allows the eye fluid to flow normally out of the eye.

H

Hippocampus

The hippocampus is a part of the brain that plays a significant role in the formation of long-term memories. The plural of hippocampus is hippocampi.

I

Impact score

The impact factor is a measure of the average number of citations per article, so the higher the number, the more “important” the journal is to the scientific community in that field.

Intraocular pressure (IOP)

Intraocular pressure (IOP) refers to the fluid pressure inside the eye.

J

Juvenile open-angle glaucoma

If primary open-angle glaucoma develops during childhood or early adulthood, it is called juvenile open-angle glaucoma.

L

Late-onset Alzheimer's disease

The majority of Alzheimer's disease cases are late-onset, usually developing after age 65. Late-onset Alzheimer's disease has no known cause and shows no obvious inheritance pattern.

Lipid

Lipids are naturally occurring molecules that include fats. 

Locus

A locus is a specific location or position of a gene on a chromosome.

M

Macrophages

Macrophages are a type of white blood cell that engulfs and digests microbes, damaged or dead cells,  and other foreign substances. .

Macula

The macula is the central  portion of the retina that processes sharp, clear, straight-ahead vision.

Major Neurocognitive Disorder

Major Neurocognitive Disorder is diagnosed when disturbance of a single cognitive ability is severe enough to interfere with independence, and the disturbance is not caused by drug use, delirium, or various other medical or psychiatric conditions. The cognitive abilities that are tested for this diagnosis are complex attention, language, executive function (skills that enable people to plan, organize, remember things, prioritize, or pay attention to tasks,  for example), visuospatial function (the visual perception of spatial relationships among objects), memory, and social cognition. Alzheimer’s disease is the most common type of Major Neurocognitive Disorder.

Mild cognitive impairment (MCI)

Mild cognitive impairment (MCI)  is a condition between normal age-related memory loss and dementia. Individuals with MCI have persistent memory problems (for example, difficulty remembering names and following conversations and marked forgetfulness) but are able to perform routine activities without more than usual assistance. Individuals with MCI are at risk of developing Alzheimer's disease or other forms of dementia.

Mild Neurocognitve Disorder

Mild Neurocognitive Disorder is diagnosed when disturbance of a single cognitive ability requires compensatory activities. One example is having to write everything down in order to remember. Mild Neurocognitive Disorder, by definition, is not bad enough to rob a person of basic independence. The cognitive abilities that are tested for this diagnosis are complex attention, language, executive function (which are skills that enable people to plan, organize, remember things, prioritize, or pay attention to tasks,  for example), visuospatial function (the visual perception of spatial relationships among objects), memory, and social cognition. One possible cause of Mild Neurocognitive Disorder is Alzheimer’s disease.

Myocilin

Myocilin is a protein common to parts of the eye and other neural tissues. Genetic mutations cause it to become misshapen through a process known as “protein misfolding.” That, in turn, triggers production of fibrous amyloidresidue that clog the drainage channels of the eye.

N

Neurodegeneration

Shrinkage of the brain caused from neural damage and neuron cell loss, resulting in a measurable loss of brain volume. 

Neurodegenerative diseasess

Neurodegeneration is a  term for a range of conditions that cause deterioration and loss of function of brain cells. Examples include Alzheimer's disease,  frontotemporal dementia, Parkinson's disease, and amyotrophic lateral sclerosis (ALS).

Neurofibrillary tangles

Neurofibrillary tangles are insoluble twisted fibers found inside the brain's nerve cells. They primarily consist of a protein called tau, which forms part of a structure called a microtubule. The microtubule helps transport nutrients and other important substances from one part of the nerve cell to another. In Alzheimer's disease the tau protein is abnormal and the microtubule structures collapse.

Neurons

Neurons are the core components of the brain and spinal cord of the central nervous system (CNS) that process and transmit information.

Normal-tension glaucoma (NTG)

Sometimes glaucoma can occur when the pressure inside the eye is "normal." This condition is called normal-tension glaucoma

O

Ocular hypertension

Ocular hypertension is a condition in which the measured eye pressure is consistently greater than “normal." However, there is no obvious damage to the optic nerve as detected by an eye examination, optic nerve imaging, or evidence of visual field change. In other words, there is no evidence of glaucoma yet.

Open-angle glaucoma (OAG)

Open-angle glaucoma is the most common form of the disease. It is progressive and characterized by optic nerve damage. The most significant risk factor for the development and advancement of this form is high eye pressure. Initially, there are usually no symptoms, but as eye pressure gradually builds, at some point the optic nerve is impaired and peripheral vision is lost. Without treatment, an individual can become totally blind.

Optic nerve

A bundle of more than one million nerve fibers, or axons, which carry visual information from the eye to the brain.

P

Photoreceptors

The light sensing nerve cells (rods and cones) located in the retina.

Primary angle-closure glaucoma (PACG)

Angle-closure glaucoma, also called narrow-angle glaucoma, may be acute or chronic. In acute angle-closure glaucoma, the normal flow of eye fluid (aqueous humor) between the iris and the lens is suddenly blocked. Symptoms may include severe pain, nausea, vomiting, blurred vision, and seeing a rainbow halo around lights. Chronic angle-closure glaucoma progresses more slowly and can damage the eye without symptoms, similar to open-angle glaucoma.

Primary open-angle glaucoma (POAG)

Open-angle glaucoma is the most common form of the disease. It is progressive and characterized by optic nerve damage. The most significant risk factor for the development and advancement of this form is high eye pressure. Initially, there are usually no symptoms, but as eye pressure gradually builds, at some point the optic nerve is impaired and peripheral vision is lost. Without treatment, an individual can become totally blind.

Prions

Prions are natural human proteins that, under certain conditions, can interact with other prion proteins, ultimately forming harmful deposits in the brain.  Prions have been implicated in dementia-causing diseases such as mad cow disease and scrapie in animals, and Creutzfeldt-Jakob Disease (CJD) and Gerstmann-Straussler-Scheinker syndrome (GSS) in humans.

Prodromal

Prodromal is another term for early Alzheimer’s diesease; it equates with a condition also known as mild cognitive impairment (MCI).

Pseudoexfoliation glaucoma

Pseudoexfoliation glaucoma occurs when there are flakes of material at the edge of the pupil, on the lens, in the drainage structures, and throughout other structures primarily in the front of the eye. When the eye’s drainage system is clogged by this flaky pseudoexfoliative material, the eye pressure can increase and lead to glaucoma.

Pupil

The adjustable opening at the center of the iris through which light enters the eye.

R

Retina

The retina is the light sensitive layer of tissue that lines the back of the eye and transmits visual information via the optic nerve to the brain, which interprets this information as images.

Retinal pigmented epithelium (RPE)

A pigmented layer of cells sandwiched between the photoreceptors and the choroid. These cells protect and nourish the retina, remove waste products, prevent new blood vessel growth into the retinal layer, and absorb light not absorbed by the photoreceptor cells; these actions prevent the scattering of the light and enhance clarity of vision.

S

Schlemm’s canal (SC)

A connecting passageway in the eye where aqueous humor is absorbed into blood vessels and eliminated through the bloodstream.

Sclera

The sclera is the tough outer coat that protects the entire eyeball.

Stargardt disease

Stargardt disease is an inherited form of macular degeneration. While it affects the same part of the central retinal, called the macula, it is different from age-related macular degeneration. Patients with Stargardt disease often develop symptoms including difficulty reading, black spots in their central vision, or changes in color perception between the ages of 10 and 40. The disease is also known as fundus flavimaculatus.

 

Sundowning

Sundowning is a symptom of Alzheimer’s disease and other forms of dementia. Confusion and agitation worsen in the late afternoon and evening, or as the sun goes down. Symptoms are less pronounced earlier in the day. Sundowning most often affects people who have mid-stage and advanced dementia. The phenomenon of sundowning is also sometimes called “late-day confusion.”

Synapses

Synapses are structure that permits nerve cells to pass an electrical or chemical signal to another cell.

Systemic disease

A disease that can affect the entire body.

T

Tau

The neurofibrillary tangles found in Alzheimer's disease consist primarily of a protein called tau, which forms part of a structure called a microtubule. The microtubule helps transport nutrients and other important substances from one part of the nerve cell to another. In Alzheimer's disease, however, the tau protein is abnormal and the microtubule structures collapse. Abnormal tau formations, known as “tauopathy,” have been associated with a number of neurodegenerative disorders.

Tau tangles

In Alzheimer’s disease, tau collects in fibrous deposits known as “tau tangles” that appear to damage and destroy neighboring brain cells. Left untreated, these tangles, in most cases, become toxic to neurons, and is associated with memory loss, cognitive difficulties, and other outward symptoms of Alzheimer’s disease.

Tauopathies

The growth of lethal tau formations, known as “tauopathy,” has been associated with many neurodegenerative disorders.

Trabecular meshwork (TM)

The trabecular meshwork, located near the cornea, is the spongy tissue that serves as the eye's primary drainage channel for aqueous humor.

Trabeculotomy

A trebeculotomy is a surgical procedure that helps reduce pressure in the eye by opening the eye’s drainage system, which allows eye fluid (aqueous humor) to drain out of the eye. This procedure is performed only on children.

V

Vascular dementia

Vascular dementia occurs when there are problems with blood supply to the brain, often due to mini strokes. Blood flow restriction deprives brain cells of oxygen and results in difficulties with planning, judgment, reasoning, memory and other cognitive processes.

Ventricles

Chambers within the brain that contain cerebrospinal fluid.

W

Wet macular degeneration

Wet macular degeneration (AMD) is usually preceded by the dry form of the disease. As the dry form worsens, abnormal blood vessels sometimes grow behind the macula. These vessels are fragile and will leak fluid and blood (hence the term “wet” macular degeneration). This accumulation of fluids lifts the macula, which distorts vision and causes damage to the macula. In wet AMD, straight lines may appear wavy, and central vision loss can occur rapidly. Straightahead vision can become distorted or lost entirely in a short period of time—sometimes within days.

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