In the paper it says:

> Our behavioral study showed that administration of SARS‑CoV‑2 spike protein S1 subunit (S1 protein) to mouse hippocampus induced cognitive deficit and anxiety‑like behavior in vivo.

About the BioNTech/Pfizer mRNA vaccine Wikipedia says:

> It is composed of nucleoside-modified mRNA (modRNA) encoding a mutated form of the full-length spike protein of SARS-CoV-2, which is encapsulated in lipid nanoparticles. [1]

So it seems it's at least the other way around. To me it doesn't sound too far fetched to consider that vaccines might have similar effects. But I am not a doctor either so this is just speculation.

[1]: https://en.wikipedia.org/wiki/Pfizer%E2%80%93BioNTech_COVID-...