Comment on The Caretaker - Everywhere At The End Of Time - Stages 1-6 (Complete)

Dementia is an umbrella term that encompasses the following diseases: Lewy Body Dementia, Vascular Dementia, Frontotemporal dementia, Parkinon's, Alzheimer's, Huntington's

Robin Williams had Lewy Body Dementia. He had severe depression caused by his deteriorating mind while the diagnosis to his disease was still unknown to him at the time.
Susan Schneider Williams wrote a paper where she recounts his life and his last days.

 https://n.neurology.org/content/87/13/1308

 

excerpt taken from "How the Mind Works" by Steven Pinker

    "when the visual area of the brain are damaged, for example, the visual world is not simply blurred or riddled with holes. Selected aspects of visual experience are removed while others are left intact. Some patients see a complete world but pay attention only to half of it. They eat food from the right side of the plate, shave only the right cheek, and draw a clock with twelve digits squished into the right half. Other patients lose their sensation of color, but they do not see the world [in blank and white]. Surfaces look grimy and rat-colored to them, killing their appetite and their libido. Still others can see objects change positions but cannot see them move ... The stream from a tea pot does not flow but looks like an icicle; the cup does not gradually fill with tea but is empty and then suddenly full.
    Other Patients cannot recognize the objects they see: their world is like handwriting they cannot decipher. They copy a bird faithfully but identify it as a tree stump. A cigarette lighter is a mystery until it is lit. When they try to weed the garden, they pull out the roses. Some patients recognize inanimate objects but cannot recognize faces. The patient deduces that the visage in the mirror must be his, but does not viscerally recognize himself. he identifies John F. Kennedy as Martin Luther King, and asks his wife to wear a ribbon at a party so he can find her when it is time to leave. Stranger still is the patient who recognizes the face but not the person: he sees his wife as an amazingly convincing impostor.
    These syndromes are caused by an injury, usually a stroke, to one or more of the thirty brain areas that compose the primate visual system. Some areas specialize in color and form, others in where the object is, others in what an object is, still others in how it moves... When we gaze at the world we do not fathom the many layers of apparatus that underlie our unified visual experience, until neurological disease dissects them for us."

though the quote only focuses on the visual parts of the brain, it illustrates just how complex our minds can be in our mere perception of the world.
no doubt, with the sporadic nature in which dementia damages the entire brain, dysfunctions on all parts of a person's way of life are to be expected.