There are many strategies you can adopt to prevent someone with Dementia developing pressure ulcers: firstly, make sure that the cushions on their chair are suitable - if they are sitting for long periods of time, you may want to consider a cool-gel or alternating air-system, as these are designed to lessen the load on a sitting person's pressure points.  Secondly, make sure that the person with Dementia is in a chair that has tilt-in-space functionality - this will enable you to put them into a "zero gravity" position, greatly lessening the risk of pressure wounds.  Chairs such as the Lento Care Chair or Lento Neuro are great options for someone with Dementia.