Hi I had gone through your query. Mono can affect your memory in form of registration and recall difficulties. Investigation like MRI can help to find out affected brain regions. MMSE means mini mental status examination can help to identify early cognitive deficit which can be part of old age. vyanse can be given in chronic fatigue syndrome but it is not advisable if you have only fatigue without any other associated symptom. It is psycho stimulant can be avoid until it is required. So discuss with your doctor about it and get advise. proper psychological and neurological evaluation will give more confirmatory idea. so consult and get help. I hope i have answered your query. Feel free to ask. Thank you.