Can lost long-term memories could be retrieved?

What help people increase or regain lost memories? When severe learning impairment and memory loss after a disease that rob them of their memory and ability to learn. Thyroid deficiency, Alzheimer's disease or other types of dementia can rob people of memory.

My dad has Alzheimer's and his brain is atrophied. It's smaller. I don't believe in my heart that the memories are there. He's had a massive die-off of brain cells. The connections between cells can regenerate, but the cells themselves, once dead, don't come back to life, and we can't grow new ones (hence the interest in stem cells, which CAN make new neurons grow).
If it's just the connections between neurons that are gone, yes, that can be fixed. But a dead neuron? I don't think so.

The biggest problem here is the ancient question of how and where our memories are stored. If you are metaphysical and you believe the memories/personality are reside in your soul, which is etheric and not part of your physical body (although it inhabits it) then of course all the memories are still there.
If you are very scientific then you believe memories and personality are 100% physical in nature. In that case, any damage to the parts of the brain that hold memory is permanent.

hypnosis Ive heard has awesome results when it comes to this....Or you can try Salvia Divinorum. That stuff always brings up random memory's when I try it....Weird stuff

Hi my dad works at a center where there is people that have lost there long term memory for the most part the memories are not coming back, the best thing is to support the person and help them come to terms with the fact the memories have gone. seeing a neurologist would be the best way to find out if its permanent or not.

Yes, through the use of regressive hipnosis.