A map of broken brain networks shows why people lose speech in language-based dementia

For the first time, scientists at Northwestern Medicine have identified the location of dysfunctional brain networks leading to impaired sentence production and word search in primary progressive aphasia (PPA), a form of of dementia in which patients often lose their language or thought. process.

With this discovery, scientists mapped out three areas of the brain that do not speak to each other, inhibiting speech production, research, and comprehension of words. For example, some people can not associate words to form sentences, others can not name objects or understand simple words such as "cow" or "table".

The card can be used to target these areas of the brain with therapies, such as transcranial magnetic stimulation (TMS), to potentially improve the speech of an affected person.

"We now know where to target people's brains to improve their language," said Dr. Borna Bonakdarpour, Senior Professor of Neurology at the Center for Cognitive Neurology and Alzheimer's Disease at Northwestern University's Feinberg School of Medicine and Neurologist from Northwestern Medicine.

PPA occurs in patients with neurodegenerative disorders, including Alzheimer's disease and frontotemporal degeneration.

Interactions between the three major brain regions are responsible for the way people treat words and sentences. The PPA occurs when there is a lack of connectivity between these areas. Different types of connectivity failure between these regions can result in different subtypes of APP.

The results will be published on September 1st in the journal Cortex. The large study (73 patients) was recruited from the vast pool of APP patients at the Northwestern Center for Cognitive Neurology and Alzheimer's Disease, one of the largest in the world.

The study used a functional MRI, which monitors brain activity by detecting blood flow, in order to locate brain regions that speak to each other or not. This can not be shown with the structural MRI.

Previous research used structural MRI to locate only areas of the brain that had atrophied, and scientists were unclear how a physiological deficiency in these areas correlated with symptoms experienced by a patient. This study is new because it looked at functional brain regions (not atrophied) and focused on networks between functional regions to see if they were connecting or not. This allowed scientists to correlate the functional areas of the brain with the symptoms of ASD patients.

"Previous studies on structural changes in the brain looked like archeology, in which scientists were locating areas of the brain that were already dead," said Bonakdarpour. "But we are looking at the parts of the brain that are still alive, which makes them much easier to target with treatment."

Bonakdarpour and his colleagues began testing TMS on the three brain regions targeted in healthy individuals for the purpose of applying it to patients with PPA in a future clinical trial.