Can overusing caffeine cause dementia or alzheimers in a 20 year especially with concurring insomnia condition . specifically does it cause brain shrinkage and can the brain recover . i think i was misdiagnosed with dementia praecox ?

If you don't think you're schizophrenic or psychotic or have dementia, seek another opinion from a psychiatrist. . Chronically poor quality sleep has been known to cause cerebral atrophy. . I would assume heavy caffeine intake is a factor in your insomnia.

Caffeinated coffee or tea does NOT cause dementia, and in fact, may be protective. But using caffeine late in the day can result in stimulation which does prevent adequate sleep, and this can cause "brain fog". The "shrinkage" maybe most likely secondary to dehydration, and is invariably reversible. I too would endorse a psychiatric consult to get all of this clarified.