No. Patients with Alzheimer’s / dementia lose memories because their brains have defects. Their brain scans likely reveal that parts of their brains have been damaged or not functioning properly.
– If you have information on this (brain scans of such patients), please share.
Both “saññā nirodha” and “saññāvedayita nirodha” take place in people with properly functioning brains.
One gets to “saññā nirodha” by doing a version of anariya meditation where one discards ALL thoughts that come to the mind.
On the other hand, only an Arahant can get to “saññāvedayita nirodha” which is the experience of FULL Nibbana in this life.
– The correct Anapanasati meditation of DISCARDING immoral thoughts and CULTIVATING moral thoughts (and eventually kusala thoughts) lead to the Arahanthood.
– Moral thoughts BECOME kusala thoughts when one comprehends the futility of existence in any of the 31 realms and, in general, the dangers of the rebirth process.
– Understanding that last part, happens at the Sotapanna stage. Implementation of that will be complete only at the Arahanthood.