A protein that is implicated in abnormal clumps called Lewy bodies, which are seen in the brains of people with Parkinson’s disease and some dementias. Disorders in which alpha-synuclein accumulates inside nerve cells are called synucleinopathies.
The most common cause of dementia in people age 65 and older. Nearly all brain functions, including memory, movement, language, judgment and behavior, are eventually affected.
The brain’s “fear hub,” which helps activate the fight-or-flight response and is also involved in emotions and memory.
A protein found in the characteristic clumps of tissue (called plaques) that appear in the brains of people with Alzheimer’s disease.
anterior cingulate cortex
Is involved in attention, emotional responses and many other functions.
The long, fiberlike part of a neuron by which the cell sends information to receiving neurons.
Contains the nucleus and cytoplasm of a cell.
The boundary separating the inside contents of a cell from its surrounding environment.
chronic traumatic encephalopathy
A form of dementia caused by repeated traumatic brain injury.
A progressive disorder characterized by nerve cell loss and atrophy in multiple areas of the brain.
The substance filling a cell containing all the chemicals and parts needed for the cell to work properly.
A term for a collection of symptoms that significantly impair thinking and normal activities and relationships.
dementia with Lewy bodies
A type of Lewy body dementia that is a common form of progressive dementia.
The point of contact for receiving impulses on a neuron, branching off from the cell body.
A neurotransmitter mainly involved in controlling movement, managing the release of various hormones and aiding the flow of information to the front of the brain.
The “recipe of life,” containing inherited genetic information that helps to define physical and some behavioral traits.
The study of how environmental factors such as diet, stress and postnatal care can change gene expression (when genes turn on or off) without altering DNA sequence.
A group of dementias characterized by degeneration of nerve cells, especially those in the frontal and temporal lobes of the brain.
A segment of DNA that codes to make proteins and other important body chemicals.
The most common neurotransmitter in a person’s body, which increases neuronal activity, is involved in early brain development and may also assist in learning and memory.
A portion of the brain involved in creating and filing new memories.
A dementia that results from infection with the human immunodeficiency virus that causes AIDS.
hypothalamic-pituitary-adrenal (HPA) axis
A brain-body circuit that plays a critical role in the body’s response to stress.
An electrical communication signal sent between neurons by which neurons communicate with each other.
Lewy body dementia
One of the most common types of progressive dementia, characterized by the presence of abnormal structures called Lewy bodies in the brain.
magnetic resonance imaging (MRI)
An imaging technique that uses magnetic fields to take pictures of the brain’s structure.
Dementia in which one form of dementia and another condition or dementia cause damage to the brain, for example, Alzheimer’s disease and small vessel disease or vascular dementia.
A type of vascular dementia caused by numerous small strokes in the brain.
A change in the code for a gene, which may be harmless or even helpful, but sometimes give rise to disabilities or diseases.
A network of neurons and their interconnections.
Bundles of twisted filaments found in nerve cells in the brains of people with Alzheimer’s disease. These tangles are largely made up of a protein called tau.
A nerve cell that is the basic, working unit of the brain and nervous system, which processes and transmits information.
A chemical produced by neurons that carries messages to other neurons.
A structure within a cell that contains DNA and information the cell needs for growing, staying alive and making new neurons.
Parkinson’s disease dementia
A secondary dementia that sometimes occurs in people with advanced Parkinson’s disease. Many people with Parkinson’s have the amyloid plaques and neurofibrillary tangles found in Alzheimer’s disease, but it is not clear if the diseases are linked.
A highly developed area at the front of the brain that, in humans, plays a role in executive functions such as judgment, decision making and problem solving, as well as emotional control and memory.
A neurotransmitter that regulates many functions, including mood, appetite and sleep.
The tiny gap between neurons, where nerve impulses are sent from one neuron to another.
A protein that helps the functioning of microtubules, which are part of the cell’s structural support and help deliver substances throughout the cell. In Alzheimer’s disease, tau twists into filaments that become tangles. Disorders associated with an accumulation of tau, such as frontotemporal dementia, are called tauopathies.
A type of dementia caused by brain damage from cerebrovascular or cardiovascular problems, usually strokes.