Everyone knows the infamous parapsychologist, Dr. Vladimir Zukhar, whose presence was so unbearable for Korchnoi in Baguio that he demanded to remove him from the first rows of the playing hall.
But there was another doctor working with Karpov on that match - the famous Soviet general practitioner and oncologist Mikhail Lazarevich Gershanovich (1924-2013) who devised an effective treatment for Hodgkin's lymphoma, among other things. Here's an excerpt from a 2008 article about him that mentions chess:
Match of the Century
Even already working in the Oncology Institute, Mikhail Lazarevich still helped many people as a general practitioner.
For a long time, for instance, he treated Mikhail Tal's mother.
"Once I saw a frail young man with Tal", Mikhail Lazarevich told us. "I asked him, "Who's that boy?" And Tal answered, "Remember him: he's the future world champion, Anatoly Karpov."
"Tolya was a very sickly man. Before an important game, he would often suffer from low blood pressure or high temperature. He needed constant doctor's attention. So I started to work with him.
"The first game between Karpov and Smyslov took place in Leningrad, in the Internal Ministry's Culture House. I came to the match with my wife and her friend. The women sat in the first row in short skirts and confused Smyslov a bit.
"Karpov won and started asking me to visit all his matches. So, I've seen more than 200 of his games. It was interesting, since I was myself a first-category player.
"In 1978, I was called up by CPSU Central Committee and told that I had to prepare Anatoly for his World Championship match against Korchnoi. The match took place in Baguio, Philippines, during the rain season. Impassable mud, completely antisanitary environment. Troubles with drinking water. We washed our teeth with Pepsi Cola. We bought food in random shops each time, fearing foul play. Korchnoi, as you know, defected from USSR recently, and this gave certain ideological shade to the competition.
"The atmosphere was very nervous. Tolya slept very badly, but I was wary of giving him sleeping pills - they could affect his mind.
"Karpov had a strange personality. Some spirit of opposition probably lived inside him.
"I saw it and exploited that fact. For instance, when Karpov needed a walk at the street, I would ask him, "You won't go out today, of course?"
"Tolya would exasperatedly put his street clothes on and go out.
"At first, the match went very well. Karpov led 5:0 (Gershanovich probably confused the Korchnoi match with the first Kasparov match, where Karpov indeed led 5:0), but then he got tired and started losing.
"When the score was 5:3, Moscow called: "What's going on here? Don't you see that Karpov should necessarily win? The country needs that, and you need that too."
"And at that moment, I understood that if Karpov lost, I would have to take the blame. Since then, I worried for the result even more than the chess players themselves. I returned home with heart arrythmia. Thankfully, everything went well."