Primary progressive aphasia is characterized by gradual deterioration of language, with non-fluent, fluent, and mixed forms. It can be confused with Alzheimer’s disease.

Primary progressive aphasia includes several neurodegenerative disorders of the dominant hemisphere of language, including Alzheimer’s disease, frontotemporal dementia, and stroke.

It generally begins between the ages of 45 and 70 with an isolated language disorder and is characterized by a slowly progressive onset language disorder, affecting the production and/or understanding of language. This disorder appears isolated for a few years.

There are different forms of progressive primary aphasia:

• Progressive fluent aphasia is characterized by a decline in word comprehension. Spoken language is fluent, though sometimes with difficulty in finding the appropriate word, and grammar is mostly preserved.
• Progressive logopenic aphasia, characterized by decreased verbal production and difficulty finding words, with grammar remains retained.
• Progressive non-fluent aphasia. In this case, it is firstly the production of language that is altered. Speech is slowed down and the construction of sentences full of mistakes. There are phonemic paraphasias (difficulties in the sequence of phonemes). Language comprehension remains virtually intact. Progressive nonfluent aphasia is sometimes the first manifestation of corticobasal degeneration;
• primary progressive aphasia.

Progressive aphasia can be confused with  Alzheimer’s disease. Verbal comprehension is diminished in progressive fluent aphasias, resulting in a low score on the verbal memory test.

Conversely, a disorder of the lexical semantic system observed in aphasia is often a symptom in Alzheimer’s disease.

However, the importance of the semantic deterioration, the absence of true amnesia and alterations of the parietal cerebral areas make it possible often to make the distinction with Alzheimer’s disease.

A simple cognitive test such as the  Mini Mental Examination (MMSE) or the Five Word Test  can help make this distinction. Unlike Alzheimer’s patients, aphasic patients, for example, have more problems naming objects but find it easier to remember the list of five words or to copy drawings (for example two pentagons).

Epidemiology

Between 0.5 and 2.5% of patients with a neurodegenerative disease (e.g. Alzheimer’s disease) have primary progressive aphasia. Its incidence is estimated at 1/100,000 and the average survival is 8 years (minimum 3 years and maximum 17 years).

Diagnostic criteria

Most patients consult their doctor for difficulty finding words and names.

• Gradual onset and slowly progressive difficulty in finding words, naming objects, in syntax or understanding words in conversation or on an established neuropsychological test of language.
• All the difficulties encountered in everyday life during the first two years following the onset of symptoms can be attributed to the language disorder. Premorbid language function is intact (dyslexia is possible during evolution)
• Apathy, disinhibition, impaired recent memory, impaired three-dimensional vision, impaired visual recognition, and marked sensorimotor deficits are absent for the first two years of illness, which means that the patient does not meet any diagnostic criteria for another dementia pathology.
• Other cognitive functions may be affected after the first two years, but language remains the most affected function throughout the course of the disease and deteriorates more rapidly than the other functions.
• Other causes of aphasia such as stroke or tumor are ruled out by imaging.

What is the differential diagnosis of primary progressive aphasia?

If the diagnosis of progressive aphasia is not made, the doctor will look for the following pathologies:

• Brain tumors.
• Vascular pathologies (example infarction).
• Alzheimer’s disease.
• Frontotemporal dementias.
• Corticobasal degeneration.
• Progressive supranuclear palsy.
• Psychogenic language disorder.

The most common differential diagnosis of progressive aphasia is Alzheimer’s disease.

The extent of deterioration in semantics and the absence of alterations in the parietal cortex, however, often allow to distinguish it from Alzheimer’s disease. A cognitive test such as the Mini-Mental State Examination can help make this distinction. 

Progressive nonfluent aphasia is sometimes the first manifestation of corticobasal degeneration.  

Progressive supranuclear palsy may be accompanied by progressive nonfluent aphasia. The classic symptoms of progressive supranuclear palsy are parkinsonian disorders with repeated falls, psychomotor retardation, apathy and planning problems.

Practical case of primary progressive aphasia

Anamnesis

In 2008, a retired music teacher (76) presented to a geriatrician. During the interview with her doctor, her spouse noticed that:
– she showed a lack of interest in the activities she practiced before (playing bridge, going to the museum);
– she neglected herself;
– she no longer took care of her bank account, the house (shopping, washing up, etc.);
– his conversations were limited, but continues to read daily.

Neuropsychological assessment

In 2009, her condition not having improved, she carried out a neuropsychological assessment, the results of which were as follows:
– Score on the cognitive test of the  mini-mental examination (MMSE): 22/30
–  Clock test : 3/7
–  5-word test  : 9/10 (immediate recall: 5/5; delayed recall: 4/5)
– Rapid Assessment of Cognitive Functions (ERFC)
Item 1. Temporo-spatial orientation: 8/8
Item 2. Attention and memory: 8/10
Item 3. Mental calculation: 0/2
Item 4. Reasoning and judgment: 4/5
Item 5. Comprehension: 5/5
Item 6. Naming: 3*/4
Item 7. Repetition: 2/2
Item 8. Written order: 1/1
Item 9. Verbal fluency: 1*/4
Item 10. Praxies: 6/6
Item 11. Visual decoding: 1/1
Item 12. Writing: 0/2

His score is 39/50.

Diagnostic

She suffers from:
– a lack of fluency in her speech. During a semantic fluency test, the patient gives only two words belonging to the category ‘fruit’ in 2 minutes.
– Agraphia: writing disorder independently of any motor disorders. neurological disorder of motricity hampering the elementary gestures of writing.
– alexia (inability of an individual to read and understand a text).
– semantic paralexia: the subject replaces words in a text with others; language becomes unintelligible.

The other capacities are intact: episodic memory, conceptualization capacities, to perform gestures, praxis, visuo-spatial capacities, executive functions, temporo-spatial orientation.

Diagnosis: The patient probably suffers from progressive primary aphasia.