Can signs of Alzheimer's show up as early as mid 50's?

Yes, it's possible to develop Alzheimer's in one's fifties. As many as a half million people have what's called early-onset Alzheimer's, which develops any time before age 65, sometimes in the 40s and 50s. Early-onset Alzheimer's tends to run in families. It's caused by a known gene mutation.

Far more common in midlife is for normal brain aging to be mistaken for Alzheimer's. Changes in brain processing begin as early as the 20s and 30s. It's in the 40s and especially 50s, though, that these changes become evident as memory loss. It's the severity of memory loss and the speed of change that distinguish normal brain aging from Alzheimer's disease.

Other conditions and medications can also cause memory problems. That's why it's important to have a proper Alzheimer's evaluation. Alzheimer's is a disease that's diagnosed by eliminating all the other possibilities.