Is alzheimer's hereditary? both my grandmothers had it and my mother has ppa. when i can't remember something i get nervous. i'm 45.

Sometimes: About 5% of alzheimer's patients have early-onset and these people often have a single gene that's passed 50% chance from parent to child. This might be testable. Late-onset alzheimer's is probably polygenic. There's a fair chance we'll have better treatments in the coming decades.

Sometimes: Alzheimer disease (ad) often does run in families and certain genes do cause an increased risk. Less than 5% of all cases are due to one of 3 gene mutations (which give a 50% risk of having ad). Ppa is condition that is sometimes caused by ad, sometimes by ftld. With your strong family history, it might make sense to talk to your doctor about genetic counseling and/or genetic testing.