For the past month, I have noticed memory loss that I never had before. Seconds after being told a passcode, I could not remember the numbers. I cannot remember whether I performed certain tasks the previous day. I can't remember whether I took simple medications. I don't think this is normal. At age 43, am I too young to get Alzheimer's disease? I've also been feeling very tired all the time. What else could be causing my forgetfulness?