Frontotemporal lobar degeneration (FTLD) is an umbrella term describing a group of different disorders with varying clinical presentations, genetics, and pathophysiology. Although not all FTLD disorders have pathological tau as the neurobiological substrate for clinical symptoms, all FTLD disorders share some cognitive and/or motor features. Frontotemporal dementia (FTD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), argyrophilic grain disease (AGD), and amyotrophic lateral sclerosis (ALS) can all be classified as types of FTLD. As we will see in this chapter, there is significant overlap among the assorted types of FTLD disorders as well as shared clinical, genetic, and pathological characteristics among tauopathies and with the other dementias previously discussed (Alzheimer's disease and α-synucleinopathies). For strategies to ameliorate some of the secondary behavioral symptoms often associated with FTLD and other dementias, the reader is directed to Chapter 5 (Park et al, 2017; Karantzoulis and Galvin, 2011; Atri, 2016).

AGD: argyrophilic grain disease; ALS: amyotrophic lateral sclerosis; BIBD: basophilic inclusion body disease; bvFTD: behavioral variant frontotemporal dementia; CBD: corticobasal degeneration; FTDP-17: frontotemporal dementia and parkinsonism linked to chromosome 17; MND: motor neuron disease; NIFID: neuronal intermediate filament- and α-internexin-positive inclusions; nfvPPA: non-fluent variant primary progressive aphasia; PSP: progressive supranuclear palsy