Some second thoughts from a 60’s guy:

In the Westminster study, perhaps the act of walking freely in a museum space and not being at work accounts for lowered stress. And suppose a certain painting elevates cortisol. Is it a bad painting? Should we limit ourselves to art, music, movies that relax us? Are Kenny G and Yanni our greatest musicians?

Is “art helps you learn science” a one-way street? Can’t studying science create a sense of awe and wonder that enhances art appreciation?

Mental health and longevity: what about the many artists who went mad or died early? Not that art caused these problems, but that art didn’t seem to help much.

Why neuroscience exclusively? Why the brain? We experience art with our whole body (eyes, ears, skin, gut…). This is not to challenge your findings but to suggest expanding the notion of physiological impact. The creation of art (point 4) often involves complex body systems.

Thanks for a well researched and thoughtful inquiry.