Creativity is correlated with fluid intelligence, and as the brain ages, fluid intelligence begins declining in one's late 20s, with the slope of decline sharpening after 60. This decline is especially relevant to creativity in the hard sciences. In the humanities and the social sciences where creativity depends more on accumulating a huge body of disciplinary knowledge, the decline is less marked & confounded by the benefits of simply knowing more at a later age.
You may want to read some of the work of Dean Simonton; also maybe of interest:
Article A GEOGRAPHICAL THEORY OF EXCEPTIONAL HUMAN PERFORMANCE: ECON...