Is Concentration affected by things that hamper other checks?

[Peet]

As an example, the Shaken and Sickened conditions apply a -2 penalty to skill checks and ability checks. Do these penalties apply to Concentration checks?

Concentration is not defined in the glossary. Basically if it counts as an ability check or skill check then the penalty would apply. On the other hand, concentration could fall under "caster-level checks." Or perhaps it is its own unique thing.

In 3.5 concentration was a skill, and these conditions did affect concentration. From the way things are written in the core rulebook it is hard to tell if it was intentional to leave this out; a glossary entry would have clarified things.

It feels to me that RAI concentration ought to be affected by these things but RAW it seems like it doesn't.

Peet

[RJGrady]

It is neither a skill check nor an ability check.

[Starglim]

It's based on both ability score and caster level. An effect that penalises ability checks or caster level checks doesn't affect a concentration check, because it's neither of those. There could be a question, though, about an effect that alters checks based on X ability score.

[Gauss]

I believe the RAI is that it should be affected, however I think the RAW does not support it. FAQ'd

- Gauss