PET Imaging Reveals Brain Inflammation Linked to Speech Disorders and Parkinson-like Symptoms

Recent advancements in PET imaging have uncovered distinct patterns of neuroinflammation in individuals suffering from progressive apraxia of speech (PAOS), a rare neurodegenerative disorder that hampers speech planning and execution. This groundbreaking research sheds light on the potential role of brain inflammation and tau protein accumulation in the progression of PAOS, providing promising avenues for early diagnosis and targeted treatment strategies.

The study utilized innovative PET scans to map the distribution of brain inflammation in PAOS patients. It revealed that those with the disorder exhibited increased neuroinflammatory activity, especially in regions controlling movement and speech such as the premotor cortex, frontal lobes, basal ganglia, and midbrain. Interestingly, patients with Parkinson-plus features showed broader and more intense inflammatory patterns, suggesting a link between severe inflammation and the development of Parkinson-like symptoms.

Conducted on 25 PAOS patients (including 13 with Parkinson-plus syndrome) and 30 healthy controls, the research employed ¹¹C-ER176 TSPO PET scans to measure neuroinflammation and tau deposition across 84 brain regions. The findings demonstrated that PAOS patients had significantly higher inflammation levels than controls, and that these inflammatory signals correlated with signs of tau buildup. These insights could help identify neuroinflammation as a potential biomarker for disease progression.

The results of this study, presented at the Society of Nuclear Medicine and Molecular Imaging 2025 Annual Meeting and published in the Journal of Nuclear Medicine, deepen our understanding of PAOS. Previously, neuroimaging has indicated atrophy and tau accumulation in affected brain areas, but the spatial distribution of inflammation and its relationship to tau pathology and Parkinson-plus syndromes were less understood.

"These findings contribute valuable knowledge to the neuroinflammatory process in PAOS and could facilitate the development of PET-based diagnostic tools," said Ryota Satoh, an assistant professor at Mayo Clinic. "Understanding the extent and location of inflammation may improve early diagnosis and inform the design of anti-inflammatory treatments."

Ultimately, this research emphasizes the importance of neuroinflammation in neurodegenerative disorders and opens new pathways for developing targeted therapies that could potentially slow or halt disease progression.