Dear Dr. Roach: I contracted COVID on the last couple of days of a cruise in August. COVID ran its course, but I contracted a nasty lung infection that took about three weeks to clear. Following this, I developed severe achiness in my knees, to the point that I am still walking stiffly and, at times, nearly unable to walk down a hill due to extreme discomfort. There are no issues in any other part of my body.

I am well over a month into this. My family doctor says this type of localized inflammation, both in the knees and nowhere else, suggests to him that it is a result of COVID, as he has had many COVID patients come in with inflammatory ailments.

In your opinion, is this a fair diagnosis, or should I press for a more thorough examination? He tested for rheumatoid arthritis because my father suffered from this, but the blood tests were negative. I do have arthritis in one knee and some kind of injury in the other knee.

-B.R.

Answer: I agree with your physician that arthritis symptoms can flare up after COVID. A recent study showed that rheumatoid arthritis, both as a flare-up and a new disease, can occur after a COVID diagnosis. Given your family history, testing was appropriate.

Reactive arthritis can also happen after COVID, but this is not a common form of arthritis. Given your history of arthritis in the knee (probably osteoarthritis, the most common type), it's possible that this is a flare-up. Just being in bed for a prolonged time can cause osteoarthritis to worsen, but COVID infections have been shown to worsen osteoarthritis through several mechanisms.

I would have gotten at least a set of X-rays, in addition to blood testing for rheumatoid arthritis, to be sure that there isn't something unexpected, like a crystal deposition disease such as pseudogout.

Dear Dr. Roach: I have noticed that during my years in practice, many of my patients and friends who have signs and symptoms of dementia seem to fit into the category of having a higher education. This is simply an observation and not scientific.

Have there been any studies or opinions as to the correlation between education and dementia? I realize that I may have been seeing a group of people that were mostly from a more educated background; however, there seems to be a trend.

-L.H.,M.D.

Answer: Studies show that anyone can get dementia. People with higher levels of education take longer to get to a severe level of dementia where it can be easily noticed by others. It's thought that they have some "cognitive reserve."

The main ways to prevent dementia are a healthy, mostly plant-based diet (such as a Mediterranean-style diet) and regular physical exercise. Alcohol very likely increases the risk of dementia, even at moderate levels of drinking. Whether cognitive exercise like games, crosswords, number puzzles, and visual-spatial exercises slow down dementia or just provide a cognitive reserve (like education does) is debated.

I believe that your associates are more likely to have a higher education than most, so you have a skewed sample, just as you suspect.

Contact Dr. Roach at  ToYourGoodHealth@med.cornell.edu.