I have memory problems but a clear mri? i'm 21 could this be alzeihmers? no family history of dementia.

Not likely: Memory can be confused with focus and concentration. It would be highly unlikely that the beginning of Alzheimer's at your age. Stress can also cause us not to focus and create the memory threads to recall things at a later date. Review your life and see where you can cut down on stress. Use assistance with writing things down, making lists, doing one thing at a time instead of multitasking and see if it helps good luck!

If you have Downs: syndrome (Trisomy 21) you may have early Alzheimer's. Otherwise i would look to another reason for your memory problems. Start with looking at your quality of sleep, B12 level, thyroid and other medical conditions. Are other cognitive domains affected? Do you have a history of TBI, seizure, drug use or encphalitis? A Behavioral Neurologist or Neuropsychiatrist may help if no answer is apparent.