Actress Marilu Henner has hyperthymesia — aka a superior autobiographical memory — which allows her to recall in precise detail all the events in her life. Around 60 people worldwide share this ability.

Now it seems that for some folks who contracted COVID-19, the immune system has an overactive memory too. Four recent studies shine light on how immune system inflammation triggers long COVID-19, and how it persists.

Apparently, you can "recover" from COVID-19 and then, months later, get hit with brain fog, fatigue, and other symptoms of long COVID.

And a study that looked at data on around 3,000 participants in the COVID Symptom Study Biobank found that symptoms of long COVID-19, such as problems with memory, attention, reasoning, processing speed and motor control, could persist for two years or more, especially for people who had severe case of COVID-19.

But mental problems aren't the only symptoms of long COVID that appear. Apparently cardiovascular problems are related as well.

There are new reports of a "Blue Leg Symptom" that's caused by standing up. Legs turn red, then blue, with veins bulging and skin itching. It's the result of a substantial, abnormal increase in heart rate — and doctors may not associate it with having had COVID-19.

Other unexpected symptoms of long COVID include sleep disturbances, breathing problems, loss of taste and smell, and skin rashes.

If you're contending with suspected symptoms of long COVID, consider joining a clinical trial. The NIH is opening enrollment in several associated with the RECOVER study.