MAPT and frontotemporal dementia: Tauopathies may be further distinguished by the predominant isoform content of the tau inclusions: 4R tau (e.g., progressive supranuclear palsy, corticobasal degeneration, globular glial tauopathy), 3R tau aggregations (e.g., Pick disease), or mixed (e.g., AD) (see Figure 4).