It's not a 6% higher risk, it's nearly double the risk - i.e. 7% vs 13.2%.
"Dementia occurred among 96 of 730 participants (13.2%) with adult ADHD and 7630 of 108 488 participants (7.0%) without adult ADHD."
"Dementia occurred among 96 of 730 participants (13.2%) with adult ADHD and 7630 of 108 488 participants (7.0%) without adult ADHD."
This really matters for things with a very low probability.
And the difference between the two is?
"Per cent means one hundredth of something. Percentage point is used when comparing percentages to one another. For example, when inflation drops from three to two per cent, inflation decreases by one percentage point and 33.3 per cent."
When you say it is 6 percentage points higher it means you had a percentage Y% and it is now (Y+6)%, a value which cannot be determined unless you know Y, never mind the reference absolute value it relates to.
In this particular case you can say it went from 7% to 13.2%, so if you ignore "%" as the unit the actual change is from 7 to 13.2; a ((13.2-7)/7) ≈ 0.8857 = 88% change. Had the original percentage been say 67%, a 6.2 p.p. change would have increased the percentage to 73.2%; a much smaller ((73.2-67)/67) ≈ 0.0925 = 9% change.
Had the change been "six percent of seven percent", the new value would be 7+7*(6/100) = 7.42 (percent).