Dementia and cancer ?

Thanks for replying! Your's is the FIRST to note someone with BOTH AD & Ca. I'm sorry your Mother has the double whammy. Having either would give a person the other, and some of us caregivers both! 

 Except that almost NO ONE seems to come down with both!    Why?

My guess is that true AD ( as contrasted with cardio-vascular/circulatory caused demential, TIA/stroke caused dementia, brain trauma caused dementia) is an immune system reaction, or over-reaction, which affects the way that person's body chemistry re-absorbs certain proteins, like Beta-Amyloid plaques and Tau tangles.

OK, if one's immune system is spiking, peaked and even over-reacting ( enough to perhaps cause dementia of the AD type ) , that immune system would be so strong it would recognize and target most cancers. The very auto-immune reaction that targets abnormal and potential replicating cancer cells and sends killer T cells to eat them may , unfortunately,  be responsible for a plaques and tangles accumulation in the brais.

Thus, no cancers, but Dementia of the Alzheimer's Type instead.

And the folks with no AD type dementia may be the ones who have cancers.

My "theory"  doesn't explain your mother's double whammy though, does it?  Perhaps her dementia looks like AD but is actually caused by a cardio-vascular insufficiency?  less blood circulating to her brain? Perhaps because her colon cancer has constrained her physical activity? ( which would combine with stress that cancer also brings on a person, and bring down her immuneo-reaction )  Or because  anesthesia from surgery, or chemicals in the Chemo cocktail have had unexpected consequences on her immune system ? 

My "victim" has always had an incredibly strong and complete immune system; a full spectrum "full court" body defensive system. No cancers! But she has this strange plaques and tangles accumulation going on in her brain. Her MRI shows atrophy ( synapses zapped out ) on the left side of her brain, and most of her right side functioning has been slowly lost. All other systems seem normal for her age. She has no sign of trauma, stroke, or vascular disease.

She's 73, and this is our 14th year coping. Now she can no longer walk, talk,  feed herself or keep herself clean - so we do all that for her. Stage 7 of 7. So it's late in the game for us. But maybe the immune system and how it reacts holds the key for others.

I'm intrigued by the apparent absence of cancers in most who have Dementia of the Alzheimer's Type . Why don't cancer and AD show up together in patients, at the same general rate? Why are most with cancer  free from DOAT? Why are most with DOAT free of cancers?  

 I recall Dr. Virginia Livingston-Wheeler ( her book was titled "The Conquest of Cancer" ) noted that patients with any TB , active or history or positive TB reaction seldom had cancers. She knew she could cure TB, so ( among her early experiments) she gave cancer patients TB to spike their immune systems and defeat the cancers, then she administered drugs to defeat the TB.

So, are folks with DOAT also those with huge immuno-response systems? Thus no cancers?