First thing cerebral atrophy
with neurodegenarative changes is a continuous process .........so we cant stop it and because of this he may have sleepless nights,confused behaviour specially after sun downing,forgetfullness,talking things of past or names that date back to 10-20 years ago....if like this symptoms are there alzhaimers disease...dementia is the most common cause.Do start with donepezil
memantidine and neuroprotectors like citicholine piracetam and heavy doses of multivitamin
.If fearfullness suspiciousness etc r there bettre add with anti psychotics....and dont forget to consult a psychiatrist
before giving any medication.