One thing she has never been tested for is Lyme disease. This is a contentious topic, it seems, but it is clear that Lyme disease - which is spread by a tick bite - can induce these kind of symptoms, sometimes many years after the initial tick bite. And the end stage of serious infection is a condition involving dementia.
At the age of 18, S spent a year doing VSO in Ethiopia where Lyme disease is endemic. During her time there she was ill with the same kind of symptoms as those mentioned above and was thought to have altitude sickness.
In the late 1980's, S spent 3 weeks in the Philipines, another area where the ticks that can cause Lyme disease are found.
We have mentioned all this to the Professor at various points during the last few years. He did not seem particularly convinced by the Lyme disease possibility but was for a long time of the view that S's problems could be the result of, or could have been exacerbated by, viral-type infection (actually, I believe that Lyme disease is caused by bacteria though the symptoms are similar to viral diseases). He actually referred us to a colleague who was supposedly investigating any possible link though this did not really get us anywhere, maybe because the guy - who seemed to have a penchant for diagnosing difficult conditions - was actually an expert in fungi, rather than viruses. He did blood tests which showed the presence of both Herpes viruses, of which more later.
So we never really got anywhere with this line of enquiry, but there remain unanswered questions about the illnesses that S kept getting, what caused them, and what the long-term effects might have been.
Interestingly, although still gets very tired at times, virtually all the other 'viral' symptoms have long since disappeared. She is seldom 'ill' now, apart from having a dodgy brain!