Multiple tau isoforms, as splicing alternatives in neurofibrillary tangle formation, would correlate with progression of dementia as seen with Alzheimer's disease and frontotemporal dementia, and also with various “tangle-only” dementias such as Pick's disease, corticobasal degeneration, progressive supranuclear palsy, and argyrophilic grain disease. The gene discussed is MAPT; the disease is frontotemporal dementia.