There has been a fair amount of research on chemobrain in recent years - yes its real. but new research shows that it starts at cancer diagnosis with the resulting PTSD. So basically you don't have to have chemo to have chemo brain. You just have to have the diagnosis.
So chemo brain or cognitive function disorder comes from stress. I definitely understand this. The new research did explore other possibilities in that cancer could impact certain thingies in the brain. But I'm sticking with stress.
You know if you are in a stressful time period or situation, your brain starts to run a mile a minute and you can't remember anything. I think we all remember where we were when we heard those words 'you have cancer', but then do we remember much else from the next few moments? And then we all start to panic on some level 'am I going to die?'. Then our brains dissolve further.
The ensuing days, weeks and months are full of stress as we try to control our panic and figure out how to handle our treatment as we make decisions - surgery, chemo, and more. Our brains keep melting. Then the chemo drugs start to have an impact on more brain cells. By the end of it all, we feel we can't remember anything.
I think for me my brain further went to mush with the onset of fibro fog, but I can't remember.