To me, the wording doesn't necessarily imply causality, but it does imply a repeated-measures design. Something being "associated with an increase in symptoms" is different than something being "associated with higher symptoms"; the former suggests that participants were measured at multiple time points, and there is a factor that could explain that change over time. But reading through the study, it was just a single time point.

Regardless, you're correct that it also shouldn't be taken to imply a causal relationship.