Hi all, I am now 5 months into my first postdoc. I am in life sciences, and I have switch subfields when moving from PhD to this postdoc (by switch subfields I mean change of disease being studied, e.g. from Alzheimer's disease to Parkinson's disease, and therefore techniques as well). Now, my contract is for one year and I am starting to think about my next step. Can someone let me know if it is a great idea to change subfields between postdocs or should I just stay in the same subfield? Would really appreciate if someone can shed some light as I really have no idea.

I think it is common in Postdoc. You work in a "closer" field where the fund is available. If you like the other field, it should be absolutely fine.

I don't know what the correct advice is.
However, My PhD was in wastewater treatment (using reators), after my PhD I work as a research microbiologst (undergrad and 3 chapter in my PhD related to this) for 6 months, before starting a post-doc (2 years but leaving after 1 for a job closer to home) in reactors for biofuel production (ethanol) and in a few weeks a start another post doc in alchol production for the food industry.
I haven't came across to much issues which crossing over fields, once the underlying skill set are the same. Hope that helps

There is nothing wrong with switching subfield if you have the relevant transferrable skills. If anything some PIs like you having a broad range of experience.