What is Primary Progressive Aphasia?
Primary Progressive Aphasia (PPA) is a form of dementia that can occur in individuals under the age of 65 (and sometimes as early as in the 40’s), and involves a decline in one or more language functions. It is due to brain cell degeneration.
“Aphasia” is a general term used to refer to deficits in language functions. Our language functions include speaking, understanding what others are saying, repeating things we have heard, naming common objects, reading and writing.
PPA begins very gradually and initially is experienced as difficulty thinking of common words while speaking or writing. PPA progressively worsens to the point where verbal communication by any means is very difficult. The ability to understand what others are saying or what is being read also declines. In the early stages, memory, reasoning and visual perception are not affected by the disease and so individuals with PPA are able to function normally in many routine daily living activities despite the aphasia. However, as the illness progresses, other mental abilities also decline.
The time frame within which these changes occur varies greatly between patients. A few cases have been reported in which language deficits were the only symptoms for at least 10 years. On average, impairments are confined exclusively to the area of language for approximately 5 years, but may spread to other areas after 2 years.
Primary Progressive Aphasia
- A form of dementia caused by a disease process in the brain that results in degeneration of nerve cells in the parts of the brain that control our ability to use language
- Begins with the slow decline of the ability to use language in speaking, understanding, reading and writing
- Other types of mental processes are relatively normal initially and may remain normal for years, but begin to decline with time
- This form of dementia is more prevalent in males than in females in comparison to dementia that involves forgetfulness or memory loss, which is more prevalent in females
- This form of dementia is also more common in younger individuals, with symptoms usually starting in the 50’s
The types of language difficulties that occur differ among individuals, but generally involve things such as the following:
- Increased difficulty thinking of words that results in: – substituting the wrong word (e.g., “school” for “work”) – mistakes in pronunciation (e.g., “track” for “truck”) – talking around the word (e.g., “We went to the place where you can get bread” for the words “grocery store”)
- Problems reading or writing that result in: – inability to write checks, letters – difficulty following written directions, reading signs
- Reduced ability to understand speech – trouble following conversations, especially in larger groups – asking for information to be repeated and misunderstanding things that are said, even though hearing is normal
- Decreased use of language – speech may become empty of any real information and difficult to understand early in the course of the illness – eventually may be unable to use speech to communicate, becoming mute
- Problems in arithmetic and calculations – may lose ability to perform even simple mathematical operations – may have problems making change
Despite the difficulties that occur with PPA, many of those who have this disorder are capable of normal, or even superior, achievements in activities that do not rely on language. The following activities are some of the things our patients have told us they can still do:
- Help a relative build a house
- Design a model boat that appeared in a magazine
- Maintain a highly landscaped garden
- Paint artistic pictures
- Travel to foreign countries
- Maintain a rigorous exercise regimen
- Build furniture
What is the brain disease that causes Primary Progressive Aphasia?
There are different types of degenerative brain diseases, each one due to a different abnormality in the brain tissue itself. Each of the following types of degeneration (also called neuropathology) has a specific type of abnormality in the brain cells. These are detectable only under a microscope when a postmortem brain autopsy is performed.
- Alzheimer’s disease (AD)—abnormalities in the cells are called neurofibrillary tangles and senile neuritic plaques
- Pick’s disease (PD)—abnormalities in the cells are called argentophyllic inclusions or Pick bodies
- Nonspecific degeneration (NSD)—there is evidence of brain cell death, but no features of Alzheimer’s or Pick’s disease
- Parkinson’s disease—abnormalities in cells are called Lewy bodies and these are in areas that control movement
- Corticobasalganglionic degeneration—the brain cells in a specific part of the brain (called the basal ganglia) show signs of degeneration and special characteristics under the microscope
- Diffuse Lewy Body Disease—Lewy bodies are found in the parts of the brain that control thinking and behavior
The most common type of brain degeneration found after brain autopsy in individuals with PPA (60% of cases) is Nonspecific degeneration. Less commonly, Pick’s or Alzheimer’s disease may be found. Typically, however, Alzheimer’s disease neuropathology invades brain areas that control our ability to learn new information and retain it. Therefore, the most common form of dementia associated with Alzheimer’s disease takes the form of memory loss (forgetfulness).
What is the relationship between Primary Progressive Aphasia (PPA) and dementia?
- “Dementia” is a general term for a disorder of the brain usually caused by the degeneration of brain cells. (See next page)
- Symptoms consist of a gradual, often initially unnoticed decline in an individual’s customary mental abilities and/or personality. They progress and worsen over time.
- Eventually, assistance is required even in routine activities of daily living.
- Dementia can take one of several forms. The most common type of dementia is the progressive memory loss that affects individuals over age 65 and that is caused by Alzheimer’s neuropathology.
- Dementia can also occur in much younger individuals and when it does, the symptoms are usually not in the area of memory, but rather in other mental abilities, including language, perception and personality.
As indicated, PPA is one form of dementia in which a person’s language functions deteriorate, initially without a decline in memory, personality, or other mental functions. Although at first only language ability is impaired, eventually other mental abilities also decline. The first cases of progressive aphasia were described in 1982 by Mesulam. Because aphasia is usually caused by stroke and thus begins suddenly, PPA was originally called “Slowly Progressive Aphasia.” Many other cases of PPA have been reported since then. Other “atypical” forms of dementia have also been described, including a progressive decline in visual perception (Progressive Visuospatial Dysfunction), a progressive decline of reasoning, personality and social appropriateness (Progressive Comportmental Dysfunction, also known as Fronto-temporal Dementia), and progressive difficulties in the articulation of speech, but not in the ability to use words properly (Progressive Dysarthria). Progressive Dysarthria is often mistaken for PPA, but a careful examination can distinguish between the two.
A disorder of the brain that results in changes in cognition and behavior from one’s usual abilities and characteristics that:
- Progresses over time
- Eventually interferes with the ability to carry out routine daily living activities
- Usually strikes over the age of 65, but some forms can begin in the 40’s
What causes dementia?
Dementia is caused by brain disease that is progressive. Dementia can be caused by a series of strokes (due to an interruption of the blood supply to the brain) or, more often, by diseases that cause the brain cells to degenerate. In both instances, brain cells die. In the case of stroke, the change may be abrupt, but some forms of so-called “vascular dementia” are more gradual in their course. In the case of degenerative dementia, brain cells die gradually because—for reasons we do not fully understand—“pathological” particles accumulate in the brain and prevent the cells from functioning normally. The more cell loss, the more consistently abnormal the behavior becomes, though occasionally there are days when behavior may even seem “back to normal.”
Why are the symptoms of dementia different from one person to another?
The difference in symptoms among individuals has to do with which areas of the brain are most affected by the disease. One way to think of the brain is as a factory that produces thought, memory, emotion and all the faculties that make us human. As in a factory, where many different operations are combined to yield a marketable product, there are different “departments” in the brain, or “networks,” that are specialized for performing different jobs as we think, remember and speak. Each network is made up of groups of brain cells and the connections between them.
Figure 1 illustrates a highly simplified drawing of the human brain and shows the regions involved in two different networks: one for language and one for learning new information and remembering it (or what we call explicit memory). An area deep in the temporal lobe of the brain, known as the “hippocampus,” is a very important part of the network involved in our ability to form new memories and to retain them so that we can recall them after hours, days, or months have passed. Individuals who have degeneration in the hippocampus will have “short term memory” problems. They will not be able to learn new information. However, they will be able to remember things from the past because that ability is controlled by a different part of the brain. This form of memory loss can occur from stroke, but it also is the most common form of dementia in individuals over the age of 65 and it is caused by Alzheimer’s disease degeneration in the brain.
In PPA, the degeneration occurs on the left side of the brain in the frontal, temporal and parietal regions that normally control language function, (Figure 1). Because other brain regions are not affected in the early stages of the disease, there is no loss of memory or other mental symptoms. This allows individuals with PPA to function independently even when their speech or language comprehension is significantly impaired. Thus, the type of dementia symptoms (e.g., memory, language, etc.) are not related to what causes the brain damage (stroke vs. degeneration vs. other disease), but rather to where the damage occurs, what particular area of the brain is injured.
Figure 1: The Language and Learning/Remembering Regions of the Brain
A view of the external surface of the left side of the brain. The left side of the figure is facing forward. The red line encircles the language network which is only operative on the left side of the brain. The same region on the right side of the brain controls visual perception.
Internal surface of the right side of the brain. The red line encircles the network that allows us to learn new information and recall it at a later time. Unlike the language network, this region on both sides of the brain is involved in new learning and memory.
Cognitive Neurology and Alzheimer’s Disease Center, Northwestern University, Feinberg School of Medicine
© 2002 Northwestern University