About 2 to 10 percent of dementia cases are frontotemporal dementia, a group of diseases in which nerve cell degeneration occurs in the frontal and temporal lobes of the brain, according to the National Institute of Neurological Disorders and Stroke. The majority of patients begin having symptoms between the ages of 40 and 65.

Several disorders fall under the grouping of frontotemporal dementia. These include semantic dementia, Pick’s disease and primary progressive aphasia.

The symptoms of frontotemporal dementia fall into two main categories: behavior changes and language difficulties.

For example, with behavioral changes, the patient may have a decline in her personal hygiene, participate in more inappropriate actions, including socially inappropriate behaviors, and experience a loss of empathy. She may also overeat and have a lack of judgment.

Other behavioral symptoms of frontotemporal dementia include repetitive compulsive behavior, apathy, and a lack of awareness of these changes.

https://www.empowher.com/dementia/content/what-frontotemporal-dementia