A massive international study of more than 3,100 COVID patients has revealed a marked difference in the reporting of brain-related symptoms worldwide. In the US, the vast majority of non-hospitalized patients described brain fog, depression and anxiety. Far fewer patients in countries like India and Nigeria reported the same problems. The difference is not the virus itself, but the culture, stigma and approach to mental health care. The study thus explains why long-term COVID brain fog appears to be much worse in the US.