Research can be true or flawed. The results of research can be affected by so many conditions that could make it biased. So we cannot assume that the research conducted by this group is reliable/or valid. There should be more research on these areas for a comprehensive conclusion.
From my perspective exposing children to these AI tools might reduce their creativity. Children need to develop creative thinking skills independently. Exposing them to these tools might make them depend solely on these tools.
But for adults, AI will cause more good than harm. In this world where most people don't have time to engage in other activities because of work. If AI is not against the rules of any given task, I don't see any reason not to use it. AI saves time so that we can think creatively about other things in life.
This without experiment even you can tell that consistent use of AI damages the brain, makes lazy and creates many slow intelligent people in the community. For this reasons schools are already going against the use of AI for assignments or projects, reasons why most students are now dull is because everything can be solved with the use of AI, including mathematical questions that requires deep thoughts of calculation is now completed in few seconds.
We love AI but we are not also ready for the wrong side, we also can't stop AI developments and advancement but we can manage how we live with it not to damage our lives beyond repair.