Agnosia: A loss of the ability to recognize objects, persons, sounds, shapes or smells without injury to the primary sensory organ or memory loss.

Agrammatism: The presence of grammatical errors in speech, such as the omission or incorrect usage of articles (“cow jumped over moon”), prepositions (“dog walk bridge”) or verbs (“cat eated mouse”).

Aphasia: A loss of the ability to produce and/or understand language due to injury to brain areas specialized for these functions.

Apraxia: The loss of the ability to perform tasks that require remembering patterns or sequences of movements (like waving goodbye).

Associative Agnosia: A failure to assign meaning to an object, animal or building that is clearly perceived. For example, a patient with an associative visual agnosis might be able to draw a cow, but would not know what a cow was or did.

Atrophy: Wasting away or shrinking. Neuronal atrophy is wasting away of neurons, a decrease in neuronal density.

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C9ORF72: A genetic change that causes a huge expansion in one part of a gene on chromosome 9. The C9ORF72 repeat expansion is the most common cause of familial FTLD and ALS identified to date.

Cellular Inclusion: Any small intracellular body found within a cell.

Chromosome: Strands of DNA compressed and organized into a double helix structure. Humans typically have 23 pairs of chromosomes.

Chromosome 17q21 (FTDP-17): The chromosome that contains the gene for making the protein tau.

Cortex: The outer portion of an organ. In the brain, the outer portion of the cerebrum is the cerebral cortex.

CT (computerized tomography): Pictures of structures within the body created by a computer that takes the data from multiple X-ray images and turns them in pictures. Using the same dosage of radiation as that of an ordinary X-ray machine, an entire slice of the body can be made visible with about 100 times more clarity with the CT scan.

Dementia: A deterioration of intellectual faculties, such as memory, concentration and judgment, resulting from an organic disease or disorder of the brain. It is sometimes accompanied by emotional disturbance and personality changes.

DNA (deoxyribonucleic acid): The complex molecule that holds the "blueprint" for your body to make proteins.

Episodic Memory: The memory of events, times, places, associated emotions and other conception-based knowledge in relation to an experience.

Frontal Lobe: The part of each hemisphere of the brain located behind the forehead that serves to regulate and mediate the higher intellectual functions. The frontal lobes have intricate connections to other areas of the brain. In the frontal lobes, we meld emotions, cognition, error detection, volition, a sense of self, and more to create our social brain.

Frontal Variant FTD (fvFTD): An older term for behavioral variant FTD (bvFTD)

Frontotemporal Dementia (FTD): The umbrella term for the clinical syndromes of behavioral variant frontotemporal dementia (bvFTD), semantic dementia (SD) and progressive non-fluent aphasia (PNFA). These syndromes share involvement of the frontal and temporal lobes of the brain. This term is sometimes used to refer specifically to bvFTD.

Frontotemporal Lobar Degeneration (FTLD): The term that describes the specific pathological diseases that result in FTD syndromes. Subtyping is based on the specific proteins found within neuronal inclusions.

Gene: A specific subunit of DNA that codes for a specific protein.

Gliosis: A process leading to scars in the central nervous system that involves the production of a dense fibrous network of neuroglia (supporting cells) in areas of damage. Gliosis is a prominent feature of many diseases of the central nervous system, including frontotemporal dementia, Alzheimer's disease, multiple sclerosis and stroke. After a stroke, neurons die and disappear with replacement gliosis.

Gray Matter: The cortex of the brain which contains nerve cell bodies. The gray matter is in contrast to the white matter, the part of the brain that contains myelinated nerve fibers. The gray matter is so named because it appears gray.

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MRI (magnetic resonance imaging): A special radiology technique that uses magnetism, radio waves and a computer to produce images of internal specific structures. An MRI is painless, does not use x-ray radiation and is a powerful tool for delineating brain structure.

Microtubules: A key structural element of the scaffolding structure of a cell or cytoskeleton.

Mutation: A permanent change in the DNA or RNA - the molecular "blueprints" that direct the building of proteins. Mutations can be helpful, neutral or harmful and can be caused randomly or by environmental factors.

Neurofibrillary Tangle: Pathological clusters of the protein tau that are found within neurons.

Neuronal Inclusion: Any small intracellular body found within a neuron (nerve or brain cell).

non-fluent/agrammatic variant Primary Progressive Aphasia (nfvPPA): One of the language variants of frontotemporal dementia (FTD)

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Pathology: The study and diagnosis of disease through examination of organs, tissues, bodily fluids or whole bodies.

Pedigree: In medicine, a family health history diagrammed with a set of international symbols to indicate the individuals in the family, their relationships to one another, those with a disease, etc.

Phonemic Paraphasias: Errors involving use of the incorrect phoneme (“ped” instead of “bed”) or transposition of a phoneme (“efelant” for “elephant”).

Pick Bodies: A specific type of cellular inclusion made up of the protein tau and seen in some people with frontotemporal dementia (FTD)

Pick’s Disease: Another name for behavioral variant frontotemporal dementia (bvFTD), which has also been called FTD

PPA (primary progressive aphasia): A neurodegenerative disease marked by the progressive decline of language functions. PPA has now been split into three subgroups: semantic variant primary progressive aphasia (svPPA), non-fluent/agrammatic variant primary progressive aphasia (nfvPPA), and logopenic variant primary progressive aphasia (lvPPA).

Presenting Symptom: The first change noticed by the patient or caregiver; the change that brings them into the doctor's office.

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semantic variant Primary Progressive Aphasia (svPPA): One of the language variants of frontotemporal dementia (FTD)

Semantic Memory: The memory of meanings, understandings and other concept-based knowledge. Remembering that a robin is a bird with a red breast is one example of semantic knowledge

Semantic Paraphasia: The substitution of a word that is closely related to the target word, as in "cat" for “dog”

Tau: A protein in the body that aids in the cellular structure (cytoskeleton) and cellular transportation.

Tauopathy: A neurological disease involving abnormal tau proteins.

Temporal Lobe: The lobe of the cerebral hemisphere located down on the side of the brain near the ears. The temporal lobe contains the auditory cortex which is responsible for hearing, language comprehension and memory.

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White Matter: The part of the brain that contains myelinated nerve fibers. The white matter is white because it is the color of myelin, the insulation covering the nerve fibers. The white matter is as opposed to the gray matter (the cortex of the brain which contains nerve cell bodies).