The brain region discovered that only the processes were spoken and unwritten.

Patients participating in a new Northwestern Medicine study were able to understand words written but not spoken aloud. They could write the names of the things they saw but not verbalize them.

Even though these patients could hear and speak fluently, a disease had crept into a part of their brain that prevented them from processing the auditory words while allowing them to treat those that were visual. Patients participating in the study had primary progressive aphasia (PPA), a rare type of dementia that destroys the tongue and currently receives no treatment.

The study, published March 21 in the journal Cognitive and behavioral neurology, allowed scientists to identify a region of the left brain that has not been studied so far, which seems specialized in the treatment of auditory words.

If a patient in the study saw the word "hippo" written on a piece of paper, he could identify a hippopotamus in memory cards. But when this patient heard someone say "hippopotamus", they could not show the image of the animal.

"They had trouble naming it aloud but did not have visual cue issues," said Sandra Weintraub, lead author, professor of psychiatry and behavioral science and neurology at the Feinberg School of Medicine. Medicine of Northwestern University. "We still think that these degenerative diseases are at the root of a generalized impairment, but we learn early on that neurodegenerative diseases may be selective depending on the areas of the brain being attacked."

For most patients with APP, communication can be difficult because it disrupts the auditory and visual processes in the brain.

"It's usually very frustrating for APP patients and their families," said Weintraub, also a member of the Northwestern Mesulam Center for Cognitive Neurology and Alzheimer's Disease. "The person seems to be fine, she does not drink and yet, it's a different person.That means that you have to readapt to that person and learn new ways to communicate."

Remarkably, the four patients in this study could still communicate with others in writing and by reading due to a particular type of brain pathology, the TDP-43 type A.

"It does not happen often that you just have a disability in one area," said Weintraub, explaining that the brain is compartmentalized, so that different networks share the work of seemingly easy tasks, such as reading a word and be able to say that is aloud. "The fact that only the auditory words have been altered in these patients and that their words have remained intact leads us to believe that we have identified a new area of ​​the brain where raw sound information is transformed into images of auditory words."

The results are preliminary because of the small size of the sample, but scientists hope that they will spur more tests of this type of impairment in future APP patients and will contribute to the design. therapies focused on written communication rather than oral communication.

While 30% of APP cases are caused by molecular changes in the brain due to Alzheimer's disease, the most common cause of this dementia, especially in the under-60s, is degeneration frontotemporal lobar. Patients in this study had FTLD-TDP type A, which is very rare. The fact that this rare neurodegenerative disease is badociated with a unique clinical disorder of language is a new discovery.

The study followed the patients longitudinally and examined their post-mortem brain. Weintraub emphasized the importance for people who participate in longitudinal brain studies when they are alive and donate their brains to science after their deaths for the scientific community to learn. more on how to keep the brain healthy.

"We know so much about the heart, liver, kidneys, eyes and other organs, but we know so little about the brain in comparison," Weintraub said.

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The study was funded in part by grant RO1 008552 from the National Institute of Deafness and Other Communication Disorders; the AG13854 grant from the National Institute on Aging; and the National Institute for Neurological Disorders and Stroke awards grants R35 NS097261 and T32 NS047987. The first author of the study is Dr. Marek-Marsel Mesulam, director of the Mesulam Center for Cognitive Neurology and Alzheimer's Disease, professor of neurology at Feinberg, and neurologist at Northwestern Memorial Hospital. Robert S. Hurley and Eileen H. Bigio of Northwestern are also co-authors.