I know someone who is having a lot of memory loss. doctors have taken brain scans but cant find anything. he loses days at a time. ?

Memory loss: The newer imaging scans are usually relatively good in finding things that may cause memory issues like dementia or poor circulation of the brain which can cause to memory loss. However the best thing to determine memory loss is to perform a neuropsychological test. These test a very specific and accurate figuring The process of memory problems. These tests are very reliable for memory problems

Memory: Consider to be checking vitamins levels such as B12 and B1, if any of those low, can be reason for memory problems. Person can be depressed also, that can lead to memory problems. Check thyroid also.

Has his G.P. or a : specialist evaluated him for systemic illnesses like heart disease, hardened arteries, diabetes, etc., for primary neurological disorders & events like Transient Ischemic Attacks, brief lack of blow flow to his brain? If no medical problem is found, he needs neuropsychological testing. If no deficits are found, then a psychiatric evaluation. Neuroimaging doesn't diagnose all possible causes.