Talking with a couple people who are caregivers for Alz/Dementia loved ones
 

and although the patients may be too far gone with their disease but maybe they need to be certain to take Mg anyway, I am advising the caregivers to take care of their own health/memory issues and found a lot of info on Mg and memory loss issues and of course Mg is vital for good sleep, which also helps to support memory, sleep is vital. Mg discussions have been a major topic here.

Magnesium Has Role in Reducing Dementia Risk - Holistic Primary Care

Magnesium Threonate is said to be the best type for memory issues.

Magnesium L-Threonate for the Enhancement of Learning and Memory in People With Dementia - Full Text View - ClinicalTrials.gov

My mag citrate is what I count on and my memory is good overall. But for those with issues, this type is recommended.