This is an interesting article. It's actually headed "Cognitive Problems Transient After AF Ablation". The main finding is that there is a temporary dip in cognition for 3m after an ablation - presumably due to the stress following an ablation.
However, by 12m, 14% of the ablation arm actually showed improvement in cognition compared with none in the control arm (where they just stayed on anti-arrhythmic drugs):
medscape.com/viewarticle/99...
Presumably this is due to the improved blood flow after a successful ablation.