Primary progressive aphasia

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Primary progressive aphasia
Aphasia.png
Regions of the left hemisphere that can give rise to aphasia when damaged.
Specialty Neurology

Primary progressive aphasia (PPA) [1] is a type of neurological syndrome in which language capabilities slowly and progressively become impaired. As with other types of aphasia, the symptoms that accompany PPA depend on what parts of the left hemisphere are significantly damaged. However, unlike most other aphasias, PPA results from continuous deterioration in brain tissue, which leads to early symptoms being far less detrimental than later symptoms.

Contents

Those with PPA slowly lose the ability to speak, write, read, and generally comprehend language. Eventually, almost every patient becomes mute and completely loses the ability to understand both written and spoken language. [2] Although it was first described as solely impairment of language capabilities while other mental functions remain intact, [2] it is now recognized that many, if not most of those with PPA experience impairment of memory, short-term memory formation and loss of executive functions.

It was first described as a distinct syndrome by M. Marsel Mesulam in 1982. [3] Primary progressive aphasias have a clinical and pathological overlap with the frontotemporal lobar degeneration (FTLD) spectrum of disorders and Alzheimer's disease. However, PPA is not considered synonymous to Alzheimer's disease due to the fact that, unlike those affected by Alzheimer's disease, those with PPA are generally able to maintain the ability to care for themselves, remain employed, and pursue interests and hobbies.

Moreover, in diseases such as Alzheimer's disease, Pick's disease, and Creutzfeldt-Jakob disease, progressive deterioration of comprehension and production of language is just one of the many possible types of mental deterioration, such as the progressive decline of memory, motor skills, reasoning, awareness, and visuospatial skills. [2]

Causes

Currently, the specific causes for PPA and other degenerative brain disease similar to PPA are viewed as idiopathic (unknown). Autopsies have revealed a variety of brain abnormalities in people who had PPA. These autopsies, as well as imaging techniques such as CT scans, MRI, EEG, single photon emission computed tomography (SPECT), and positron emission tomography (PET), have generally revealed abnormalities to be almost exclusively in the left hemisphere. [2]

Risk factors

There have been no large epidemiological studies on the incidence and prevalence of the PPA variants. Though it most likely has been underestimated, onset of PPA has been found to occur in the sixth or seventh decade. [4]

There are no known environmental risk factors for the progressive aphasias. However, one observational, retrospective study suggested that vasectomy could be a risk factor for PPA in men. [5] These results have yet to be replicated or demonstrated by prospective studies.[ citation needed ]

PPA is not considered a hereditary disease. However, relatives of a person with any form of frontotemporal lobar degeneration, including PPA, are at slightly greater risk of developing PPA or another form of the condition. [6] In a quarter of patients diagnosed with PPA, there is a family history of PPA or one of the other disorders in the FTLD spectrum of disorders. It has been found that genetic predisposition varies among the different PPA variants, with PNFA being more commonly familial in nature than LPA or SD. [4]

The most convincing genetic basis of PPA has been found to be a mutation in the GRN gene. [7] Most patients with observed GRN mutations present clinical features of PNFA, but the phenotype can be atypical. [8]

Diagnosis

Diagnostic criteria

The following diagnosis criteria were defined by Mesulam: [9] [8]

Whether or not PPA and other aphasias are the only source of cognitive impairment in a patient is often difficult to assess because: 1) as with other neurologically degenerative diseases, such as Alzheimer's disease, there are currently no reliable non-invasive diagnostic tests for aphasias, and thus neuropsychological assessments are the only tool physicians have for diagnosing patients; and 2) aphasias often affect other, non-language portions of these neuropsychological tests, such as those specific for memory. [2]

Classification

In 2011, the classification of primary progressive aphasia was updated to include three clinical variants. Patients must first be diagnosed with PPA, and then divided into variants based on speech production features, repetition, single- word and syntax comprehension, confrontation naming, semantic knowledge, and reading/spelling. [10] [11] [12] In the classical Mesulam criteria for primary progressive aphasia, there are two variants: a non-fluent type progressive nonfluent aphasia (PNFA) and a fluent type semantic dementia (SD). [13] [14]

A third variant of primary progressive aphasia, logopenic progressive aphasia (LPA) was then added, [15] and is an atypical form of Alzheimer's disease. For PNFA, the core criteria for diagnosis include agrammatism and slow and labored speech. Inconsistent speech sound errors are also very common, including distortions, deletions, and insertions. In terms of comprehension, there are deficits in syntax and sentence comprehension due to grammatical complexity, but single- word and object comprehension is relatively maintained. [10]

The second variant, SD, presents with deficits in single-word and object comprehension. Naming impairments can be severe, specially for low-frequency objects, and can eventually lead to a more widespread semantic memory deficiency over time. The ability to read and write can also be impaired if there are irregularities between pronunciation and spelling. However, repetition and motor speech is relatively preserved. [10]

The logopenic variant involves impairments in word retrieval, sentence repetition, and phonological paraphasias, comparable to conduction aphasia. Compared to the semantic variant, single word comprehension and naming is spared, however, sentence comprehension presents difficulty because of length and grammatical complexity. Speech will include incomplete words, hesitations preceding content words, and repetition. [10] However, these PPA subtypes differ from similar aphasias, as these subtypes do not occur acutely following trauma to the brain, such as following a stroke, due to differing functional and structural neuroanatomical patterns of involvement and the progressive nature of the disease. [4]

Treatment

Due to the progressive, continuous nature of the disease, improvement over time seldom occurs in patients with PPA as it often does in patients with aphasias caused by trauma to the brain. [2]

In terms of medical approaches to treating PPA, there are currently no drugs specifically used for patients with PPA, nor are there any specifically designed interventions for PPA. A large reason for this is the limited research that has been done on this disease. However, in some cases, patients with PPA are prescribed the same drugs Alzheimer's patients are normally prescribed. [2]

The primary approach to treating PPA has been with behavioral treatment, with the hope that these methods can provide new ways for patients to communicate in order to compensate for their deteriorated abilities. [2] Speech therapy can assist an individual with strategies to overcome difficulties. There are three very broad categories of therapy interventions for aphasia: restorative therapy approaches, compensatory therapy approaches, and social therapy approaches. [16]

Rapid and sustained improvement in speech and dementia in a patient with primary progressive aphasia utilizing off-label perispinal etanercept, an anti-TNF treatment strategy also used for Alzheimer's, has been reported. [17] A video depicting the patient's improvement was published in conjunction with the print article. [18] These findings have not been independently replicated and remain controversial.

History

M. Marsel Mesulam coined the term primary progressive aphasia. [19]

See also

Related Research Articles

<span class="mw-page-title-main">Aphasia</span> Inability to comprehend or formulate language

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.

<span class="mw-page-title-main">Receptive aphasia</span> Language disorder involving inability to understand language

Wernicke's aphasia, also known as receptive aphasia, sensory 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 are typically 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.

A communication disorder is any disorder that affects an individual's ability to comprehend, detect, or apply language and speech to engage in dialogue effectively with others. This also encompasses deficiencies in verbal and non-verbal communication styles. The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language. This article covers subjects such as diagnosis, the DSM-IV, the DSM-V, and examples like sensory impairments, aphasia, learning disabilities, and speech disorders.

<span class="mw-page-title-main">Apraxia</span> Medical condition

Apraxia is a motor disorder caused by damage to the brain, which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorder's severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty. Children may be born with apraxia; its cause is unknown, and symptoms are usually noticed in the early stages of development. Apraxia occurring later in life, known as acquired apraxia, is typically caused by traumatic brain injury, stroke, dementia, Alzheimer's disease, brain tumor, or other neurodegenerative disorders. The multiple types of apraxia are categorized by the specific ability and/or body part affected.

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.

<span class="mw-page-title-main">Anomic aphasia</span> Medical condition

Anomic aphasia is a mild, fluent type of aphasia where individuals have word retrieval failures and cannot express the words they want to say. By contrast, anomia is a deficit of expressive language, and a symptom of all forms of aphasia, but patients whose primary deficit is word retrieval are diagnosed with anomic aphasia. Individuals with aphasia who display anomia can often describe an object in detail and maybe even use hand gestures to demonstrate how the object is used, but cannot find the appropriate word to name the object. Patients with anomic aphasia have relatively preserved speech fluency, repetition, comprehension, and grammatical speech.

<span class="mw-page-title-main">Wernicke's area</span> Speech comprehension region in the dominant hemisphere of the hominid brain

Wernicke's area, also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is primarily involved in the production of language. It is traditionally thought to reside in Brodmann area 22, which is located in the superior temporal gyrus in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of right-handed individuals and 70% of left-handed individuals.

<span class="mw-page-title-main">Frontotemporal dementia</span> Types of dementia involving the frontal or temporal lobes

Frontotemporal dementia (FTD), or frontotemporal degeneration disease, or frontotemporal neurocognitive disorder, encompasses several types of dementia involving the progressive degeneration of frontal and temporal lobes. FTDs broadly present as behavioral or language disorders with gradual onsets. Common signs and symptoms include significant changes in social and personal behavior, apathy, blunting of emotions, and deficits in both expressive and receptive language. Currently, there is no cure for FTD, but there are treatments that help alleviate symptoms.

<span class="mw-page-title-main">Progressive supranuclear palsy</span> Medical condition

Progressive supranuclear palsy (PSP) is a late-onset neurodegenerative disease involving the gradual deterioration and death of specific volumes of the brain. The condition leads to symptoms including loss of balance, slowing of movement, difficulty moving the eyes, and cognitive impairment. PSP may be mistaken for other types of neurodegeneration such as Parkinson's disease, frontotemporal dementia and Alzheimer's disease. The cause of the condition is uncertain, but involves the accumulation of tau protein within the brain. Medications such as levodopa and amantadine may be useful in some cases.

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").

Cerebral atrophy is a common feature of many of the diseases that affect the brain. Atrophy of any tissue means a decrement in the size of the cell, which can be due to progressive loss of cytoplasmic proteins. In brain tissue, atrophy describes a loss of neurons and the connections between them. Brain atrophy can be classified into two main categories: generalized and focal atrophy. Generalized atrophy occurs across the entire brain whereas focal atrophy affects cells in a specific location. If the cerebral hemispheres are affected, conscious thought and voluntary processes may be impaired.

Semantic dementia (SD), also known as semantic variant primary progressive aphasia (svPPA), is a progressive neurodegenerative disorder characterized by loss of semantic memory in both the verbal and non-verbal domains. However, the most common presenting symptoms are in the verbal domain. Semantic dementia is a disorder of semantic memory that causes patients to lose the ability to match words or images to their meanings. However, it is fairly rare for patients with semantic dementia to develop category specific impairments, though there have been documented cases of it occurring. Typically, a more generalized semantic impairment results from dimmed semantic representations in the brain.

Progressive nonfluent aphasia (PNFA) is one of three clinical syndromes associated with frontotemporal lobar degeneration. PNFA has an insidious onset of language deficits over time as opposed to other stroke-based aphasias, which occur acutely following trauma to the brain. The specific degeneration of the frontal and temporal lobes in PNFA creates hallmark language deficits differentiating this disorder from other Alzheimer-type disorders by the initial absence of other cognitive and memory deficits. This disorder commonly has a primary effect on the left hemisphere, causing the symptomatic display of expressive language deficits and sometimes may disrupt receptive abilities in comprehending grammatically complex language.

Semantic dyslexia is, as the name suggests, a subtype of the group of cognitive disorders known as alexia. Those who have semantic dyslexia are unable to properly attach words to their meanings in reading or speech. When confronted with the word "diamond", they may understand it as "sapphire", "shiny" or "diamonds"; when asking for a bus ticket, they may ask for some paper or simply "a thing".

Logopenic progressive aphasia (LPA) is a variant of primary progressive aphasia. It is defined clinically by impairments in naming and sentence repetition. It is similar to conduction aphasia and is associated with atrophy to the left posterior temporal cortex and inferior parietal lobule. It is suspected that an atypical form of Alzheimer's disease is the most common cause of logopenic progressive aphasia.

<span class="mw-page-title-main">Corticobasal degeneration</span> Rare neurodegenerative disease

Corticobasal degeneration (CBD) is a rare neurodegenerative disease involving the cerebral cortex and the basal ganglia. CBD symptoms typically begin in people from 50 to 70 years of age, and the average disease duration is six years. It is characterized by marked disorders in movement and cognition, and is classified as one of the Parkinson plus syndromes. Diagnosis is difficult, as symptoms are often similar to those of other disorders, such as Parkinson's disease, progressive supranuclear palsy, and dementia with Lewy bodies, and a definitive diagnosis of CBD can only be made upon neuropathologic examination.

Auditory verbal agnosia (AVA), also known as pure word deafness, is the inability to comprehend speech. Individuals with this disorder lose the ability to understand language, repeat words, and write from dictation. Some patients with AVA describe hearing spoken language as meaningless noise, often as though the person speaking was doing so in a foreign language. However, spontaneous speaking, reading, and writing are preserved. The maintenance of the ability to process non-speech auditory information, including music, also remains relatively more intact than spoken language comprehension. Individuals who exhibit pure word deafness are also still able to recognize non-verbal sounds. The ability to interpret language via lip reading, hand gestures, and context clues is preserved as well. Sometimes, this agnosia is preceded by cortical deafness; however, this is not always the case. Researchers have documented that in most patients exhibiting auditory verbal agnosia, the discrimination of consonants is more difficult than that of vowels, but as with most neurological disorders, there is variation among patients.

<span class="mw-page-title-main">Posterior cortical atrophy</span> Medical condition

Posterior cortical atrophy (PCA), also called Benson's syndrome, is a rare form of dementia which is considered a visual variant or an atypical variant of Alzheimer's disease (AD). The disease causes atrophy of the posterior part of the cerebral cortex, resulting in the progressive disruption of complex visual processing. PCA was first described by D. Frank Benson in 1988.

Corticobasal syndrome (CBS) is a rare, progressive atypical Parkinsonism syndrome and is a tauopathy related to frontotemporal dementia. CBS is typically caused by the deposit of tau proteins forming in different areas of the brain.

Maria Luisa Gorno-Tempini is a behavioral neurologist and neuroscientist and a leading expert in frontotemporal dementia. She directs the ALBA Lab of the University of California, San Francisco Memory and Aging Center. She is also the co-director of the UCSF Dyslexia Center.

References

  1. ↑ "Primary progressive aphasia - Symptoms and causes". Mayo Clinic. Retrieved 2023-10-26.
  2. 1 2 3 4 5 6 7 8 "Primary Progressive Aphasia - National Aphasia Association". National Aphasia Association. Retrieved 2017-12-17.
  3. ↑ Mesulam M (1982). "Slowly progressive aphasia without generalized dementia". Annals of Neurology. 11 (6): 592–8. doi:10.1002/ana.410110607. PMID   7114808. S2CID   29107525.
  4. 1 2 3 Husain, Masud; Schott, Jonathan M. (2016). Oxford Textbook of Cognitive Neurology and Dementia. Oxford University Press. ISBN   9780199655946.
  5. ↑ Weintraub S, Fahey C, Johnson N; et al. (2006). "Vasectomy in men with primary progressive aphasia". Cogn Behav Neurol. 19 (4): 190–3. doi:10.1097/01.wnn.0000213923.48632.ab. PMID   17159614. S2CID   33013869.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ↑ Goldman JS, Farmer JM, Wood EM, et al. (Dec 2005). "Comparison of family histories in FTLD subtypes and related tauopathies". Neurology. 65 (11): 1817–9. doi:10.1212/01.wnl.0000187068.92184.63. PMID   16344531. S2CID   37191580.
  7. ↑ Spinelli EG, Mandelli ML, Miller ZA, Santos-Santos MA, Wilson SM, Agosta F, Grinberg LT, Huang EJ, Trojanowski JQ, Meyer M, Henry ML, Comi G, Rabinovici G, Rosen HJ, Filippi M, Miller BL, Seeley WW, Gorno-Tempini ML (2017). "Typical and atypical pathology in primary progressive aphasia variants". Ann Neurol. 81 (3): 430–443. doi:10.1002/ana.24885. PMC   5421819 . PMID   28133816.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. 1 2 Dickerson, Bradford C. (2016-05-19). Hodges' Frontotemporal Dementia. Cambridge University Press. ISBN   9781107086630.
  9. ↑ Mesulam MM (2003). "Primary progressive aphasia—a language-based dementia". N Engl J Med. 349 (16): 1535–1542. doi:10.1056/nejmra022435. PMID   14561797.
  10. 1 2 3 4 Gorno-Tempini ML, Hillis AE, Weintraub S, et al. (March 2011). "Classification of primary progressive aphasia and its variants". Neurology. 76 (11): 1006–14. doi:10.1212/WNL.0b013e31821103e6. PMC   3059138 . PMID   21325651.
  11. ↑ Bonner MF, Ash S, Grossman M (November 2010). "The new classification of primary progressive aphasia into semantic, logopenic, or nonfluent/agrammatic variants". Curr Neurol Neurosci Rep. 10 (6): 484–90. doi:10.1007/s11910-010-0140-4. PMC   2963791 . PMID   20809401.
  12. ↑ Harciarek M, Kertesz A (September 2011). "Primary progressive aphasias and their contribution to the contemporary knowledge about the brain-language relationship". Neuropsychol Rev. 21 (3): 271–87. doi:10.1007/s11065-011-9175-9. PMC   3158975 . PMID   21809067.
  13. ↑ Mesulam MM (April 2001). "Primary progressive aphasia". Annals of Neurology. 49 (4): 425–32. doi:10.1002/ana.91. PMID   11310619. S2CID   35528862.
  14. ↑ Adlam AL, Patterson K, Rogers TT, et al. (Nov 2006). "Semantic dementia and fluent primary progressive aphasia: two sides of the same coin?". Brain. 129 (Pt 11): 3066–80. doi: 10.1093/brain/awl285 . PMID   17071925.
  15. ↑ Gorno-Tempini ML, Dronkers NF, Rankin KP, et al. (Mar 2004). "Cognition and anatomy in three variants of primary progressive aphasia". Annals of Neurology. 55 (3): 335–46. doi:10.1002/ana.10825. PMC   2362399 . PMID   14991811.
  16. ↑ Manasco, H. (2014). The Aphasias. In Introduction to Neurogenic Communication Disorders (Vol. 1, p. 91). Burlington, MA: Jones & Bartlett Learning.
  17. ↑ Tobinick E (2008). "Perispinal etanercept produces rapid improvement in primary progressive aphasia: identification of a novel, rapidly reversible TNF-mediated pathophysiologic mechanism". Medscape Journal of Medicine. 10 (6): 135. PMC   2491668 . PMID   18679537.
  18. ↑ Tobinick, Edward (10 June 2008). "Video 1". Medscape J Med. 10 (6): 135. PMC   2491668 . PMID   18679537.
  19. ↑ Mesulam, M. M. (April 2001). "Primary progressive aphasia". Annals of Neurology. 49 (4): 425–432. doi:10.1002/ana.91. ISSN   0364-5134. PMID   11310619. S2CID   35528862.

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