WHY can chess increase IQ? They mostly refer to schoolchildre | Why?

WHY can chess increase IQ?

They mostly refer to schoolchildren and students who have higher IQs without chess. Some studies have shown that subjects who played chess had a greater increase in IQ than those who did not play chess.

On the other hand, studies by the British Institute of Education showed no significant effect of chess on cognitive ability. In any case, the positive effect of this game is small and is probably related to the training of attention and concentration.