What's Happening in the Brain
Given that loss of independence is tied up with every aspect of dementia, then the progressive loss of dependence reflects the progression of brain cell dysfunction (neurodegeneration) in dementia. In the early stages , we typically see a loss of initiative for highly skilled activities, such as banking, driving and cooking. This is followed by errors in their performance, to the point that function becomes compromised. These changes reflect degeneration in the deep middle parts of the brain, which are important for new learning and recent memory , as well as in the front part of the brain, which is essential for so-called 'executive function' (for example, the ability to judge, initiate, plan, make decisions, and understand the feelings of others).
As the disease progresses, people begin to lose the ability to carry out tasks, due to no longer having the necessary manual skills, and due to a failure of what is called 'praxis'. Praxis is the ability of the brain to integrate the many pieces of information needed to carry out a manual task, and its failure is called 'apraxia'. In addition, the failure to remember how to carry out some tasks is seen as a failure of 'procedural memory'.
As the brain cell dysfunction gets worse, these problems extend to simpler and simpler tasks. In consequence, in severe dementia, people have trouble even knowing how to eat properly.