New technique could allow dementia patients to get ahead of damage

Patients diagnosed with Primary Progressive Aphasia (PPA), a rare form of dementia, show abnormalities in brain function in areas that look structurally normal on an MRI scan, says new study conducted by the University of Arizona and the University of Toronto's Baycrest Health Sciences Centre. The research findings were published in the journal Neuropsychologia and could give therapeutic drug treatments a chance to work.

"We wanted to study how degeneration affects function of the brain," said Aneta Kielar, the study's lead author and assistant professor at the University of Arizona in the US. The team discovered that the brain showed functional defects in regions that were not yet showing structural damage on MRI scans. Structural MRI provides 3D visualisation of brain structure, which is useful when studying patients with diseases that literally cause brain cells to wither away, like PPA. Magnetoencephalography, or MEG, on the other hand, "gives you really good spatial precision as to where the brain response originates," said Jed Meltzer, the study's senior author and an assistant professor at the University of Toronto in Canada.

"We want to know if the decreased brain function is coming from the areas that are already atrophied or areas in an earlier stage of decline," Meltzer said. Kielar and her colleagues compared brain scans of patients with PPA to healthy controls while both groups performed language tasks. The researchers also imaged participants' brains while at rest. The functional defects were related to worse performance in the tasks, as individuals with PPA lose their ability to speak or understand language while other aspects of cognition are typically preserved.

Identifying the discrepancy between a PPA brain's structural and functional integrity could be used as an early-detection method. This is promising because "many drugs designed to treat dementia are proving to be not really effective and that might be because we're detecting the brain damage too late," Kielar said. "Often, people don't come in for help until their neurons are already dead. We can do compensation therapies to delay disease progress, but once brain cells are dead, we can't get them back," she said. This technique could allow patients to get ahead of the damage, researchers said.