People may be able to contract Alzheimer's during certain medical procedures in the same way as the brain disease CJD, say researchers.
Contaminated surgical instruments or injections, such as human growth hormone, may pose a rare but potential risk, they speculate in Nature.
The theoretical hunch comes from post-mortem brain studies in eight patients.
The UK experts stress that their findings are inconclusive and do not mean Alzheimer's is infectious.