Epidemiology

Age of onset: usually between 40 and 60 years (typically younger than in Alzheimer disease)

Etiology

Generally associated with pathological intracellular inclusion bodies (Pick bodies) that are caused by mutations in tau (main protein component of Pick bodies) or progranulin (precursor of granulin, which regulates cell growth) proteins

Early changes in personality and behavior → inability to observe social etiquette
- Apathy
- Disinhibited behavior
  - A pattern of socially inappropriate and often impulsive behavior that is seen in several neurological disorders
  - Examples include offensive language and inappropriate touching.
Changes in cognitive functioning
- Aphasia (but no apraxia)
- Intelligence, orientation, and memory initially intact
Motor deficits
- Parkinsonism (in later stages)

Tip

Patients with FTD display changes of personality and social behavior, but their memory generally remains intact.

Detection of different types of intracellular inclusions in surviving neurons (tau or TDP-43 in approx. 90% of cases)
- Pick bodies (FTLD-tau): round cytoplasmic inclusions of aggregated hyperphosphorylated tau proteins
- FTLD‑TDP: inclusions with ubiquitinated TDP‑43