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Agnosia and Related Terms

AGNOSIA, APHASIA, APRAXIA and Related Terms for Cognitive, Behavioral and Neurological Disorders

These terms describe altered states that are associated with brain injury (e.g., trauma, stroke, tumor) or with developmental deficits. Although the list deals with primarily CNS-associated disorders, in some cases the term does not distinguish between a CNS cause or a peripheral or neuromuscular cause. Terms that are primarily psychiatric diagnoses (e.g., schizophrenia) are not included.

AGNOSIA is a general term for a loss of ability to recognize objects, people, sounds, shapes, or smells; that is, the inability to attach appropriate meaning to objective sense-data. It usually is used when the primary sense organ involved is not impaired. APHASIA is a general term relating to a loss of language ability. APRAXIA is a general term for disorders of practice. These conditions are usually caused by brain injury due to trauma, stroke and/or tumor.

Many of these terms have two synonymous forms that differ in whether the word starts with a- or with dys- such as alexia and dyslexia. Here the a- form is usually defined and the other is noted as "syn:", except when the dys- form is the more common usage. (If you cannot find a term in one of these forms, look for it in the other. All other synonyms are defined in both forms.)

Sources: These definitions are paraphrased from definitions in a large number or print and online dictionaries. Thus this list is not meant to be considered my own, but rather is a compilation.

Note: When a word appears in italics, that indicates it is defined elsewhere in this list.


abulia - Loss of will power or ability to make decisions.

acataphasia - Inability to formulate a statement or expression in an organized manner.

acoria (syn: akoria) - Inability to feel satiated, regardless of how much is eaten.

adiadochokinesia (syn: dysdiadocchokinesia) - Inability to perform rapidly alternating movements, that is to stop a movement and follow it with another in an opposite direction.

ageusia - Impaired sense of taste.

agnosia -A general term for a loss of ability to recognize objects, people, sounds, shapes, or smells; that is, the inability to attach appropriate meaning to objective sense-data. It usually is used when the primary sense organ involved is not impaired.

agraphia - Inability to express thought in written language (usually not due to mechanical disfunction), (synonym dysgraphia).

agraphesthesia - Inability to identify a letter or number being written on some part of the body.

akathisia - Motor restlessness; an inability to sit still. Often caused by defects in the extrapyramidal system.

akinesia (syn: dyskinesia) - Unresponsiveness, with extreme reluctance to perform elementary motor activities. A form of apraxia.

alalia - Loss of ability to speak.

alexia - Loss of the ability to understand written language, i.e., to read. A subform of dyslexia.

allesthesia - Perception in a limb opposite to the one stimulated. Related to dyschiria.

alliesthesia - Perception of the same external stimulus as sometimes pleasant and sometimes unpleasant.

amentia - Extreme mental retardation.

amnesia (syn: dysmnesia) - Total or partial loss of memory. Numerous subcategories and causes exist.

amelodia (syn: aprosodia) - Absence of normal variations of pitch, rhythm and stress in speech.

amusia - Inability to produce and/or appreciate musical sounds.

anacusia - Deafness.

analgesia - Absence of a normal sense of pain.

anarthria - A general term that includes either aphonia or aprosodia.

anarithmetria (syn: dyscalcula) - Inability to use mathematics.

anergia - Listless or lacking in energy.

anhedonia - Inability to experience pleasure.

anomia (syn: dysnomia) - General term for the inability to name objects. This can be limited to inability to name objects in semantic categories such as living things, inanimate things, fruits and vegetables, colors, animals, body parts, furniture, etc. Many of these limited conditions are given special names. (A related condition is a failure to comprehend syntactical structures, but this has no specific name.)

anopsia - Blindness.

anorexia - Loss or appetite. A pathological fear of eating, in order to avoid weight gain.

anosmia (syn: anosphrasia) - Loss of the sense of smell.

anosognosia - Unawareness of, denial of, or failure to recognize one's own neurological deficit. For example someone paralyzed on their left side may claim they can move their left arm normally.

anosphrasia (syn: anosmia) - Loss of the sense of smell.

apastia - Refusal to eat.

apathy - Lack of interest or concern.

aphasia (syn: dysphasis) - This is the general term that literally means "no speech." It refers to any impairment of the ability to use and/or understand words and can be used to describe loss of one or more of the following abilities: ability to speak; ability to write; understand speech; understand written words. Major subcategories include: Broca's aphasia, in which one can comprehend speech, but not produce it; and, Wernicke's aphasia in which one can produce speech but not comprehend speech.

aphemia - Inability to speak words, but able to make other sounds.

aphonia (dysphonia) - Loss of ability to speak; inability to produce speech sounds. Distinguished from the motor defect called dysarthria, which is imperfect articulation of speech due to disturbances of muscular control.

apraxia (syn: dyspraxia)- Difficulty in performing a learned movement or coordinated motor activity even though understanding, motor function coordination, and sensation are intact. Specific apraxias may be limited to a certain group of functions, such as inability to construct a simple structure from blocks, or inability to dress oneself. Related to akinesia.

aprosodia (syn: amelodia)- Absence of normal variations of pitch, rhythm and stress in speech.

asemia - Loss or ability to express or understand symbols or signs of thought.

asitia - Lack of appetite or loathing of food.

astasis - Inability to stand due to lack of motor coordination in the presence of normal strength.

astereognosia - Inability to identify palpated objects.

asthenia - General weakness or debilitation.

asynergia - Loss of coordination of motor movement.

ataxia - Poor coordination and unsteadiness due to failure to regulate the body's posture, and strength and direction of limb movements. Often a consequence of a disorder in the cerebellum.

atonia - Lack of muscle tension or tone.

circumlocution - Evasive speech or use of unusual definitional terms.

confabulation - Answering of questions by an inappropriate, made-up attempt to explain.

dementia - General term for loss of intellectual or cognitive abilities. Many psychiatric diagnoses are in this category.

dysacusis - Distortion of sound frequency or intensity, often painful.

dysantigraphia - Inability to copy writing or printed letters.

dysaphia - Impaired sense of touch. Related to dysesthesia.

dysarthria - Imperfect articulation of speech due to disturbances of muscular control. This is distinguished from aphonia.

dysbasia (syn: abasia) - Difficulty walking, usually taking steps that are too big or too small.

dyscalcula (syn: anarithmetria)- Inability to use mathematics.

dyschiria - Inability to tell which side of the body has been touched. Related to allesthesia.

dyschronation - Lack of a sense of relativity in the consciousness of time.

dysergia - Motor impairment due to axonal transmission failure.

dyslexia - A condition in which an individual with normal vision is unable to properly interpret or produce written language. Individuals can see and recognize letters but have difficulty spelling and writing words. They have no impairment of object or picture identification. Dyslexia may have distinguishable subforms (such as alexia), and is not related to intelligence. Dyslexia is more common in males and is often first recognized as a reading difficulty in the early school grade.

dysesthesia (syn:dysaesthesia) - Abnormal sensations of the skin. Somtimes used more generally for the impairment of any of the senses. Related to dysaphia.

dyslogia - Difficulty in expressing ideas.

dysmetria - Uncoordinated movement that misses its target.

dysmimia - Inability to express oneself by gestures or signs. Inability to physically imitate.

dysmorphophobia - Obsession that a normal body part is malformed or defective in appearance.

dysorexia - Failure of appetite.

dysphagia (syn: aphagia, dysthagia) - Difficulty in swallowing.

dysreflexia (syn: areflexia) - Abnormal reflex in response to a stimulus.

dyssynergia - Disorganized muscle movement.

dysthagia (syn: aphagia, dysphagia) - Difficulty in swallowing.

dystonia - Maintenance of a persistant posture or position.

echolalia - Imitation of sounds without comprehension of their meaning. A normal developmental stage in children, but an abnormality in adults.

environmental agnosia - Inability to orient to physically familiar places but nonetheless able to orient to an abstract representation such as a map or floor plan. Related to topographagnosia.

hyperpathia - Increased reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold. This sensation is often inappropriately painful.

jargon - Normal sounding speech but made up of nonsense words.

palinopsia - Apparently seeing in a blind portion of the visual field, often a completion of an object in the adjacent normal visual field.

paragraphia - Miswriting when responding to a spoken word or number.

paraphasia - Misreading of a written word or number.

parapnasia - Use or incorrect words or word combinations.

paresis - Partial or incomplete paralysis.

phantom limb - Sensation of a missing limb still being present.

prosopagnosia - Inability to recognize faces, including one's own.

somesthesia - General term for a somesthetic (tactile) disorder.

synesthesia - An inappropriate sensory perception, such as perceiving a color in response to a particular odor.

topagnosis - Inability to localize the site of tactile stimulation.

topographagnosia - Disability to orient to an abstract spatial representation such as a map or floor plan. Related to environmental agnosia.

verbal dysdecorum - Inability to self-monitor the appropriateness of speech in social settings.