Dementia is a syndrome, not a disease. Dementia is a group of symptoms that affects mental cognitive tasks such as memory and reasoning. Dementia is an umbrella term that Alzheimer's disease can fall under. It can occur due to a variety of conditions, the most common of which is Alzheimer's disease
https://player.whooshkaa.com/shows/dementiaq
episode 39: Primary Progressive Aphasia
Unlike other forms of aphasia that result from stroke or brain injury, PPA is caused by neurodegenerative diseases, such as Alzheimers Disease or Frontotemporal Lobar Degeneration.