There are changes when freezing blood. The first study I came across stated:

red cells undergoing the non-freezing procedure and suspended in additive solutions had significantly better biochemical preservation after 21 days of storage (p < 0.001). Both procedures removed an average 98% of the initial leucocytes at the expense of 18-20% of the red cells. The non-freezing procedure resulted in higher residual concentrations of HLA class II bearing lymphocytes (p < 0.01), but not higher numbers of dendritic cells.

The second study states:

Fibrinogen activity and mass-length ratio, compaction and fibrin content of the clots made from frozen plasma were, however, all significantly affected by freezing. Mass-length ratio and compaction showed a linear decrease and fibrin content a linear increase over a 4-month frozen storage period, thereby indicating that these variables were probably not stable.

Those are just two such studies; one of red blood cells, the other of plasma. I'm not sure if those chemical changes are important for something like lifespan or reducing alzheimer's, but I would expect a person of the same blood type would be far superior to blood that's been frozen for 30 years.