From the Mayo Clinic:
The most common signs of frontotemporal dementia involve extreme changes in behavior and personality. These include:
Increasingly inappropriate social behavior
Loss of empathy and other interpersonal skills, such as having sensitivity to another's feelings
Lack of judgment
Loss of inhibition
Lack of interest (apathy), which can be mistaken for depression
Repetitive compulsive behavior, such as tapping, clapping or smacking lips
A decline in personal hygiene
Changes in eating habits, usually overeating or developing a preference for sweets and carbohydrates
Eating inedible objects
Compulsively wanting to put things in the mouth