With each form of dementia, a different network of the brain is affected
IF ONE PART FAILS, THE REST FOLLOW
The Default Mode Network of the brain is concerned with sensory activity. As well as keeping a record of all we experience in a sort of diary, it helps us find meaning behind what we perceive. With Alzheimer's, this region of the brain is affected first. Blatant flaws in the chronological order of events are seen to develop, as patients often confuse time periods of their life. Overtime, as the disease develops, the patient's memory falls away until only events occurring quite early in life are left. When we see something, we analyze it and relate it to other experiences. As this network is affected, we perceive things differently and are no longer able to relate to these experiences. This network is the most active network, and therefore breaks down the easiest. Alzheimer's is thus known as the most common form of dementia.
LEWY BODY / PARKINSON'S
Frontal Executive: Lewy Body Dementia
With Lewy Body Dementia, the region of the brain targeted deals with the ability to make and execute a plan, so the patient may display the inability to function properly. This may involve inability in specific movements,
inability to plan, inability to link things together. While those affected may recognize things, they aren't able to act in a structured manner based off of this recognition.
Salience: Frontotemporal Dementia
Common obstacles one may face if the salience network is affected: understanding own motivations, goals, what society and culture demand, what is appropriate in situations. Overall, it is harder to pick up on what other people are thinking and feeling. This network does not really affect cognition. Rather, people become totally apathetic, lethargic, unmotivated, and say exactly what they think, whether it be appropriate or not.