Semantic Variant PPA
FTD syndromes characterized predominantly by the gradual loss of the ability to speak, read, write and understand what others are saying fall under the category of primary progressive aphasia, or PPA. PPA is diagnosed when three criteria are met:
- There is a gradual impairment of language (not just speech).
- The language problem is initially the only impairment.
- The underlying cause is a neurodegenerative disease.
Experts further subdivide PPA into three clinical subtypes based on the specific language skills that are most affected.
The hallmark of semantic variant PPA (svPPA) is the progressive loss of the meanings of words. If there are additional major problems in identifying objects or faces, the condition is also called semantic dementia. Other language skills, including the ability to produce speech and to repeat phrases and sentences spoken by others, are unaffected. However, although the affected person may continue to speak fluently, their speech becomes vague and difficult to understand because many words are omitted or substituted. As the disorder progresses, people with svPPA (also known as PPA-S) may also exhibit changes in behavior similar to those seen in bvFTD, such as disinhibition and rigid food preferences.
Know the Signs…Know the Symptoms
An inability to recall the names of objects; difficulty “finding the right word.” The person affected may not be able to name a picture of a truck, or may substitute another word in the same category such as “car” for “truck.”
Reduced single-word comprehension
The person affected is unable to recall what words mean, especially words that are less familiar or less frequently used. For example, she or he may ask “What is a truck?” When asked to bring an orange, the patient may come back with an apple because the meaning of the word ‘orange’ is lost. This does not mean that the object is not recognized, as shown by the fact that the patient will not try to eat an orange without peeling it.
Impaired object knowledge
Being unable to remember what a familiar object is or how it is used. For example, the person affected may be unable to identify common kitchen utensils and how they are used in cooking. This is very unusual at initial stages of semantic PPA but may appear later.
Difficulty reading and writing words that do not follow pronunciation or spelling rules; such words are spelled or spoken “as if” they followed the rules. For example, the person affected may write “no” instead of “know,” or read “broad” as “brode.”
According to 2011 criteria, doctors will consider a clinical diagnosis of svPPA when the following symptoms are observed:
- Impaired single-word comprehension
AND three of the following:
- Impaired object knowledge
- Surface dyslexia or dysgraphia
- No reduction in ability to repeat words or phrases
- No reduction in speech production
Treatment, Management and What to Expect
Semantic variant PPA is a progressive disorder of language. In later stages of the disorder, some svPPA patients will develop symptoms common to the other FTD subtypes, including behavioral, social or motor difficulties. The language difficulty requires education for caregivers on the misunderstood nouns and gentle distraction of the agitated uncomprehending patient. As with all forms of FTD, there is no cure for sv PPA, and in most cases its progression cannot be slowed. Although no medications have been proven effective specifically in FTD, many clinicians look to symptomatic treatment approaches targeting behavioral disturbances as necessary. For instance, some individuals living with FTD benefit from selective serotonin reuptake inhibitors (SSRIs, used in treating obsessive-compulsive behaviors, such as hoarding or craving sweets).
The majority of semantic PPA cases are not hereditary.
Accumulation of TDP-43 is most commonly found at autopsy insvPPA; the remainder exhibit tau pathology.
Very rarely, some individuals diagnosed with svPPA during life are revealed to have Alzheimer’s disease pathology at autopsy.