A lot of good answers in this thread, but another thing to consider -- have you had COVID? Most people with long COVID started with a mild or asymptomatic case

A lot of good answers in this thread, but another thing to consider -- have you had COVID? Most people with long COVID started with a mild or asymptomatic case, and brain fog is a long COVID symptom. Do you have any other long COVID symptoms, like shortness of breath the you didn't have before? Sudden fatigue? Loss of vision? There is a long list of things, and a lot of them are also just symptoms of aging in general, so it's hard to tell, but if you have a lot of the symptoms and they all started within the last two years, you may have long COVID.