In aphasia, a person may be unable to comprehend or unable to formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in the Global North. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases.
Expressive aphasia is a type of aphasia characterized by partial loss of the ability to produce language, although comprehension generally remains intact. A person with expressive aphasia will exhibit effortful speech. Speech generally includes important content words but leaves out function words that have more grammatical significance than physical meaning, such as prepositions and articles. This is known as "telegraphic speech". The person's intended message may still be understood, but their sentence will not be grammatically correct. In very severe forms of expressive aphasia, a person may only speak using single word utterances. Typically, comprehension is mildly to moderately impaired in expressive aphasia due to difficulty understanding complex grammar.
Wernicke's aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent speech, which is characterized by typical speech rate, intact syntactic abilities and effortless speech output. Writing often reflects speech in that it tends to lack content or meaning. In most cases, motor deficits do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke's aphasia often suffer of anosognosia – they are unaware of their errors in speech and do not realize their speech may lack meaning. They typically remain unaware of even their most profound language deficits.
Aphasiology is the study of language impairment usually resulting from brain damage, due to neurovascular accident—hemorrhage, stroke—or associated with a variety of neurodegenerative diseases, including different types of dementia. These specific language deficits, termed aphasias, may be defined as impairments of language production or comprehension that cannot be attributed to trivial causes such as deafness or oral paralysis. A number of aphasias have been described, but two are best known: expressive aphasia and receptive aphasia.
Expressive language disorder is one of the "specific developmental disorders of speech and language" recognized by the tenth edition of the International Classification of Diseases (ICD-10). As of the eleventh edition, it is considered to be covered by the various categories of developmental language disorder. Transition to the ICD-11 will take place at a different time in different countries.
Mixed receptive-expressive language disorder is a communication disorder in which both the receptive and expressive areas of communication may be affected in any degree, from mild to severe. Children with this disorder have difficulty understanding words and sentences. This impairment is classified by deficiencies in expressive and receptive language development that is not attributed to sensory deficits, nonverbal intellectual deficits, a neurological condition, environmental deprivation or psychiatric impairments. Research illustrates that 2% to 4% of five year olds have mixed receptive-expressive language disorder. This distinction is made when children have issues in expressive language skills, the production of language, and when children also have issues in receptive language skills, the understanding of language. Those with mixed receptive-language disorder have a normal left-right anatomical asymmetry of the planum temporale and parietale. This is attributed to a reduced left hemisphere functional specialization for language. Taken from a measure of cerebral blood flow (SPECT) in phonemic discrimination tasks, children with mixed receptive-expressive language disorder do not exhibit the expected predominant left hemisphere activation. Mixed receptive-expressive language disorder is also known as receptive-expressive language impairment (RELI) or receptive language disorder.
A language delay is a language disorder in which a child fails to develop language abilities at the usual age-appropriate period in their developmental timetable. It is most commonly seen in children ages two to seven years-old and can continue into adulthood. The reported prevalence of language delay ranges from 2.3 to 19 percent.
Transcortical sensory aphasia (TSA) is a kind of aphasia that involves damage to specific areas of the temporal lobe of the brain, resulting in symptoms such as poor auditory comprehension, relatively intact repetition, and fluent speech with semantic paraphasias present. TSA is a fluent aphasia similar to Wernicke's aphasia, with the exception of a strong ability to repeat words and phrases. The person may repeat questions rather than answer them ("echolalia").
Specific language impairment (SLI) is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development, physical abnormality of the speech apparatus, autism spectrum disorder, apraxia, acquired brain damage or hearing loss. Twin studies have shown that it is under genetic influence. Although language impairment can result from a single-gene mutation, this is unusual. More commonly SLI results from the combined influence of multiple genetic variants, each of which is found in the general population, as well as environmental influences.
Landau–Kleffner syndrome (LKS)—also called infantile acquired aphasia, acquired epileptic aphasia or aphasia with convulsive disorder—is a rare childhood neurological syndrome.
Speech delay, also known as alalia, refers to a delay in the development or use of the mechanisms that produce speech. Speech – as distinct from language – is the actual process of making sounds, using such organs and structures as the lungs, vocal cords, mouth, tongue, teeth, etc. Language delay refers to a delay in the development or use of the knowledge of language.
Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, such as informing, declaring, asking, persuading, directing; acts may vary in various aspects like enunciation, intonation, loudness, and tempo to convey meaning. Individuals may also unintentionally communicate aspects of their social position through speech, such as sex, age, place of origin, physiological and mental condition, education, and experiences.
Language disorders or language impairments are disorders that involve the processing of linguistic information. Problems that may be experienced can involve grammar, semantics (meaning), or other aspects of language. These problems may be receptive, expressive, or a combination of both. Examples include specific language impairment, better defined as developmental language disorder, or DLD, and aphasia, among others. Language disorders can affect both spoken and written language, and can also affect sign language; typically, all forms of language will be impaired.
Speech–language pathology (a.k.a. speech and language pathology or logopedics) is a healthcare and academic discipline concerning the evaluation, treatment, and prevention of communication disorders, including expressive and mixed receptive-expressive language disorders, voice disorders, speech sound disorders, speech disfluency, pragmatic language impairments, and social communication difficulties, as well as swallowing disorders across the lifespan. It is an allied health profession regulated by professional bodies including the American Speech-Language-Hearing Association (ASHA) and Speech Pathology Australia. The field of speech-language pathology is practiced by a clinician known as a speech-language pathologist (SLP) or a speech and language therapist (SLT). SLPs also play an important role in the screening, diagnosis, and treatment of autism spectrum disorder (ASD), often in collaboration with pediatricians and psychologists.
In human development, muteness or mutism is defined as an absence of speech, with or without an ability to hear the speech of others. Mutism is typically understood as a person's inability to speak, and commonly observed by their family members, caregivers, teachers, doctors or speech and language pathologists. It may not be a permanent condition, as muteness can be caused or manifest due to several different phenomena, such as physiological injury, illness, medical side effects, psychological trauma, developmental disorders, or neurological disorders. A specific physical disability or communication disorder can be more easily diagnosed. Loss of previously normal speech (aphasia) can be due to accidents, disease, or surgical complication; it is rarely for psychological reasons.
Apraxia of speech (AOS), also called verbal apraxia, is a speech sound disorder affecting an individual's ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. By the definition of apraxia, AOS affects volitional movement pattern. However, AOS usually also affects automatic speech.
Speech and language impairment are basic categories that might be drawn in issues of communication involve hearing, speech, language, and fluency.
Verbal intelligence is the ability to understand and reason using concepts framed in words. More broadly, it is linked to problem solving, abstract reasoning, and working memory. Verbal intelligence is one of the most g-loaded abilities.
Developmental Language Disorder (DLD) is identified when a child has problems with language development that continue into school age and beyond. The language problems have a significant impact on everyday social interactions or educational progress, and occur in the absence of autism spectrum disorder, intellectual disability or a known biomedical condition. The most obvious problems are difficulties in using words and sentences to express meanings, but for many children, understanding of language is also a challenge. This may not be evident unless the child is given a formal assessment.
Social (pragmatic) communication disorder (SPCD), also known as pragmatic language impairment (PLI), is a neurodevelopmental disorder characterized by difficulties in the social use of verbal and nonverbal communication. Individuals who are defined by the acronym "SPCD" struggle to effectively indulge in social interactions, interpret social cues, and may struggle to use words appropriately in social contexts.
