Tau positron emission tomography imaging in C9orf72 repeat expansion carriers.

Background and purpose: AV‐1451 (18F‐AV‐1451, flortaucipir) positron emission tomography was performed in C9orf72 expansion carriers to assess tau accumulation and disease manifestation. Methods: Nine clinically characterized C9orf72 expansion carriers and 18 age‐ and gender‐ matched cognitively normal individuals were psychometrically evaluated and underwent tau positron emission tomography imaging. The regional AV‐1451 standard uptake value ratios from multiple brain regions were analyzed. Spearman correlation was performed to relate the AV‐1451 standard uptake value ratio to clinical, psychometric and cerebrospinal fluid measures. Results: C9orf72 expansion carriers had increased AV‐1451 binding in the entorhinal cortex compared to controls. Primary age‐related tauopathy was observed postmortem in one patient. AV‐1451 uptake did not correlate with clinical severity, disease duration, psychometric performance or cerebrospinal fluid markers. Conclusion: C9orf72 expansion carriers exhibited increased AV‐1451 uptake in entorhinal cortex compared to cognitively normal controls, suggesting a propensity for primary age‐related tauopathy. However, AV‐1451 accumulation was not associated with psychometric performance in our cohort. [ABSTRACT FROM AUTHOR]