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There are five different diseases that attack the language areas in the left hemisphere of the brain causing slowly progressive language impairments known as primary progressive aphasia (PPA)like the one that has forced actor Bruce Willis to retire, according to a new study from Northwestern Medicine University.
“We have found that each of these diseases affects a different part of the language network,” acknowledges the lead author, Marsel Mesulamdirector of the study.
“In some cases, the disease attacks the area responsible for grammar, in others, the area responsible for understanding words. Each disease progresses at a different rate and has different implications for intervention.”
Aphasia is a language disorder produced as a consequence of an injury or a disturbance in the functioning of the parts of the brain responsible for expression, comprehension, reading and/or writing.
Depending on the brain areas in which the lesion is located and the degree of these lesions, aphasia can have different types of severity and the patient will manifest different language problems.
Not all dementias are caused by Alzheimer’s disease. The disease is often misdiagnosed in the early stages, missing the opportunity for treatment.
This study is based on the largest set of aphasia autopsies (118 cases) ever assembled and has been published in the journal ‘Brain’.
“Patients have been studied for more than 25 years, making this the largest study to date on life expectancy, type of language impairment, and relationship of disease to details of language impairment.” , says Mesulam, also chief of behavioral neurology at Northwestern Feinberg University.
PPA patients were prospectively enrolled in a longitudinal study that included language and imaging tests of brain structure and function. The study included consent for brain donation at the time of death. It is estimated that one in 100,000 people have APP, says Mesulam.
The initial symptoms of aphasia can be subtle and can sometimes be attributed to anxiety or throat problems. Even specialists can fail to make a diagnosis in a timely manner.
In 40% of cases of aphasia, the underlying disease is a very unusual form of Alzheimer’s disease. It is unusual because it affects language rather than memory and because it can start much earlier when a person is under 65 years old.
In 60% of cases, the diseases that cause aphasia belong to a completely different group of conditions called frontotemporal lobar degeneration (FTLD). Although most people have not heard of it, frontotemporal lobe degeneration conditions are responsible for approximately 50% of all dementias that begin before the age of 65. An accurate diagnosis can now be achieved with new biochemical and imaging methods.
Once the underlying disease is diagnosed, there are many different approaches at the disease (medication) and symptomatic level. “The key is to address aphasia at both levels simultaneously,” says Mesulam.
If Alzheimer’s disease is the cause, a patient may be treated with drugs and referred to clinical trials. At the symptom level, a person who has difficulty with grammar and word search may receive targeted speech therapy. People with word comprehension would receive a different type of speech therapy, or perhaps transcranial magnetic stimulationl, which seems to work best for this particular deficit. Anxiety related to word search can be treated with anti-anxiety medications and behavioral therapy.
The next step in the research will be to improve diagnostic accuracy through new biomarkers to identify whether a patient’s aphasia is caused by Alzheimer’s disease or FTLD.
Northwestern scientists also want to find appropriate drug treatments for each disease underlying the disease and to individualize interventions. Another goal is to design non-pharmacological symptomatic interventions based on the nature of the language disorder.
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