A lot of the statements from Nisargadatta Maharaj relate to memory and the problems that arise from memories.
I originally started looking at this, as I wondered why people with dementia were not in a position to find awareness if their memories were lost. Unfortunately the conclusion from this brief look at the psychology of it tends to show that dementia affects all the types of memory, whereas Nisargadatta (unknowingly?) refers to one type of memory, namely "Episodic" Memory
There are three main types of (Long Term) Memory which were originally proposed, I read, by Tulving - whereby he differentiated between between "procedural", "semantic" and "episodic" memory.
Procedural memory is responsible for knowing how to do things, i.e. (unconscious) memory of motor skills. eg, riding a bike
Semantic memory is the part of the long-term memory responsible for storing information about the world. This includes knowledge about the meaning of words, as well as general knowledge. Specifically think of "knowing that" (say) Paris is the capital of France. It involves conscious thought / effort.
The third type, and I believe the one to which Nisargadatta refers, is Episodic Memory
This is the part of both the short and long-term memory responsible for storing information about events (i.e. episodes) and experiences in our lives.
Episodic memories tend to be about people and events in time.
They involve conscious thought, but these memories are capable of being triggered by almost any association and may "run" for long periods of reflection.
"Day-dreaming" might be another way of putting it, as this is the one that takes you out of the "here and now" of awareness.
In my opinion, this is also the type of memory that acts as a "millstone around the neck" of anyone looking for enlightenment. In simple terms, these are often the memories that interrupt and lessen the depth of meditation and the ones which tie you down at the point of death.
The ability to "push these episodic memories gently aside" is one of the keys to staying in the present, but, the trouble is, that these memories are probably the ones that define who you are.
It was the equinox a few days ago and the clocks changed to BST or whatever they call it in Europe. One hour forward, with alll the...
Since losing the self to achieve awareness can be the point of the whole enterprise, it seems to me dementia should be highly desired.
There is another kind of loss, that of loss of propioception due to stroke which is reputed to really get you there. See the TED talk Jill Bolte Taylor: My stroke of insight | TED Talk.
And there is a book that is heavy-going (I am struggling to get through it), but informative is:
The Seven Sins of Memory: How the Mind Forgets and Remembers - Kindle edition by Schacter, Daniel L.. Health, Fitness & Dieting Kindle eBooks @ Amazon