Gosh, even the mice were disbelieved. In mice, anxiety isn’t all in the head. It can start in the heart. https://www.sciencenews.org/article/mice-anxiety-brain-heart-emotion
Would that explain why people who regularly raise their heart rate, fit healthy people, are so anxious.
So, nothing at all to do with anxiety, then. Other than it being a label used for anything and everything, including the outcome of drinking too much coffee or intense exercise. Because the heart doesn't just decide to beat faster, everything else being equal. It beats faster on command using nervous and chemical precursors like adrenaline, and a lot more. Seriously all of this is basically like cosmology and geology being held back by creation narratives. Medicine is genuinely being held back by a combination of beliefs and traditions. What a total disaster they have made of "mental health".
Mice as prey animals better have redundant systems to ensure that they get the hell out of reach of predators. So nice that the Center for Complementary and Integrative Medicine in Bethesda, Maryland (USA) was super excited about this research.
