Uncovering the causes of a primary progressive aphasia (PPA), a new Northwestern Medicine study has identified five diseases that target the language centers of the left hemisphere of the brain.

A new Northwestern Medicine study has found five distinct diseases that affect the language centers of the left hemisphere of the brain, gradually resulting in language problems known as primary progressive aphasia (PPA).

According to lead author Dr. M. Marsel Mesularm, “each of these diseases hits a different part of the language network,” and “In some cases, the disease hits the area responsible for grammar, in others the area responsible for word comprehension. Each disease progresses at a different rate and has different implications for intervention.”   

This research is based on the largest collection of PPA autopsy yet gathered (118 cases).

The patients were tracked for more than 25 years, making this the most comprehensive study of life expectancy, language impairment type, and disease-language impairment association to date.

Patients with PPA were prospectively enrolled in longitudinal research that included language testing as well as imaging of brain structure and function. Consent was obtained for brain donation at death as part of the study.

PPA affects about one out of every 100,000 persons, according to Mesulam.

The first signs of PPA might be subtle, and they’re often mistaken for anxiety or throat issues. Even specialists may not be able to establish a timely diagnosis. The underlying condition in 40% of PPA instances is a very rare form of Alzheimer’s dementia. It’s odd because it affects language rather than memory, and it can begin considerably earlier in life, even before the person reaches the age of 65.

In 60% of cases, the disorders that cause PPA are classified as frontotemporal lobar degeneration (FTLD). Although most individuals are unaware of it, frontotemporal lobar degeneration is responsible for approximately half of all dementias that begin before the age of 65. With improved imaging and biochemical approaches, precise diagnosis is now possible.

Once the underlying condition has been identified, there are a variety of treatment options available on both a disease (drug) and symptomatic level.

“The trick is to approach PPA at both levels simultaneously,” Mesulam adds.

If Alzheimer’s disease is the root of the problem, a patient can be medicated and enrolled in clinical trials. An individual who has trouble with grammar and word searching can receive tailored speech therapy at the symptom level. Word comprehension problems would be treated with a new sort of speech therapy or, possibly, transcranial magnetic stimulation, which appears to be the most effective treatment for this problem. Anti-anxiety medication and behavioral treatment can help with anxiety related to word discovery.

The next stage in the research is to employ novel biomarkers to increase diagnostic accuracy and determine whether a patient’s PPA is caused by Alzheimer’s disease or FTLD. Northwestern researchers also hope to develop pharmacologic treatments that are appropriate for each condition that causes PPA and personalize interventions. Another goal is to develop non-pharmacologic symptomatic therapies that are tailored to the nature of the linguistic impairment.

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